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Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Oct. 27, 2012	Nov. 23, 2012
Document and Entity Information
Entity Registrant Name	AeroVironment Inc
Entity Central Index Key	0001368622
Document Type	10-Q
Document Period End Date	Oct. 27, 2012
Amendment Flag	false
Current Fiscal Year End Date	--04-30
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		22,416,677
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q2

Consolidated Balance Sheets - USD ($) $ in Thousands	Oct. 27, 2012	Apr. 30, 2012
Current assets:
Cash and cash equivalents	$ 70,770	$ 64,220
Short-term investments	64,694	77,152
Accounts receivable, net of allowance for doubtful accounts of $1,185 at October 27, 2012 and $921 at April 30, 2012	48,330	56,417
Unbilled receivables and retentions	21,064	27,034
Inventories, net	44,747	43,539
Deferred income taxes	9,508	9,377
Prepaid expenses and other current assets	4,837	4,030
Total current assets	263,950	281,769
Long-term investments	64,798	58,457
Property and equipment, net	22,137	23,515
Deferred income taxes	5,191	5,209
Other assets	230	201
Total assets	356,306	369,151
Current liabilities:
Accounts payable	15,430	20,213
Wages and related accruals	13,405	19,076
Income taxes payable	1,485	8,788
Customer advances	4,079	5,124
Other current liabilities	6,129	9,898
Liability for uncertain tax positions	606	606
Total current liabilities	41,134	63,705
Wages and other accruals		1,203
Deferred rent	909	1,019
Liability for uncertain tax positions	4,026	4,026
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.0001 par value: Authorized shares - 10,000,000; none issued or outstanding
Common stock, $0.0001 par value: Authorized shares - 100,000,000 Issued and outstanding shares - 22,417,977 at October 27, 2012 and 22,243,903 at April 30, 2012	2	2
Additional paid-in capital	128,614	124,954
Accumulated other comprehensive loss	(667)	(694)
Retained earnings	182,288	174,936
Total stockholders' equity	310,237	299,198
Total liabilities and stockholders' equity	$ 356,306	$ 369,151

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Oct. 27, 2012	Apr. 30, 2012
Consolidated Balance Sheets
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 1,185	$ 921
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, Authorized shares	10,000,000	10,000,000
Preferred stock, issued shares	0	0
Preferred stock, outstanding shares	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, Authorized shares	100,000,000	100,000,000
Common stock, Issued shares	22,417,977	22,243,903
Common stock, outstanding shares	22,417,977	22,243,903

Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Consolidated Statements of Income - USD ($) $ in Thousands	Oct. 27, 2012	Oct. 29, 2011	Oct. 27, 2012	Oct. 29, 2011
Revenue:
Product sales	$ 52,415	$ 47,858	$ 81,105	$ 77,157
Contract services	27,863	32,514	57,850	65,212
Total revenue	80,278	80,372	138,955	142,369
Cost of sales:
Product sales	28,215	28,499	48,774	46,371
Contract services	16,427	21,243	35,040	43,653
Total cost of sales	44,642	49,742	83,814	90,024
Gross margin	35,636	30,630	55,141	52,345
Selling, general and administrative	13,176	12,240	26,797	25,940
Research and development	9,386	8,816	17,522	16,402
Income from operations	13,074	9,574	10,822	10,003
Other income:
Interest income	162	106	334	184
Income before income taxes	13,236	9,680	11,156	10,187
Provision for income taxes	4,498	3,093	3,804	3,274
Net income	$ 8,738	$ 6,587	$ 7,352	$ 6,913
Earnings per share data:
Basic (in dollars per share)	$ 0.40	$ 0.30	$ 0.33	$ 0.32
Diluted (in dollars per share)	$ 0.39	$ 0.30	$ 0.33	$ 0.31
Weighted average shares outstanding:
Basic (in shares)	22,030,330	21,763,927	21,980,453	21,743,990
Diluted (in shares)	22,383,791	22,255,943	22,353,434	22,244,697

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 27, 2012	Oct. 29, 2011	Oct. 27, 2012	Oct. 29, 2011
Net income	$ 8,738	$ 6,587	$ 7,352	$ 6,913
Other comprehensive (loss) income:
Unrealized (loss) gain on investments, net of tax	(10)	41	27	43
Total comprehensive income	$ 8,728	$ 6,628	$ 7,379	$ 6,956

- Definition

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the reporting entity. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, but excludes any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References + Details

- Definition

Net of tax amount of the appreciation (loss) in value of unsold available-for-sale securities attributable to the parent entity. Excludes amounts related to other than temporary impairment (OTTI) losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4569643-111683

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=18733093&loc=SL4573702-111684

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 19
-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4569616-111683

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph c(3)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 29
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 30
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Oct. 27, 2012	Oct. 29, 2011
Operating activities
Net income	$ 7,352	$ 6,913
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	5,937	4,141
Provision for doubtful accounts	566	246
Deferred income taxes	(130)	(296)
Stock-based compensation	1,642	1,535
Tax benefit from exercise of stock options	1,529	376
Excess tax benefit from stock-based compensation		(90)
Changes in operating assets and liabilities:
Accounts receivable	7,521	18,559
Unbilled receivables and retentions	5,970	290
Inventories	(1,208)	(3,298)
Other assets	(836)	(607)
Accounts payable	(4,783)	(11,517)
Other liabilities	(18,772)	(6,481)
Net cash provided by operating activities	4,788	9,771
Investing activities
Acquisitions of property and equipment	(4,559)	(5,484)
Net sales of held-to-maturity investments	5,911	31,623
Net sales of available-for-sale investments	250	225
Net cash provided by investing activities	1,602	26,364
Financing activities
Excess tax benefit from stock-based compensation		90
Exercise of stock options	160	323
Net cash provided by financing activities	160	413
Net increase in cash and cash equivalents	6,550	36,548
Cash and cash equivalents at beginning of period	64,220	62,041
Cash and cash equivalents at end of period	70,770	98,589
Supplemental disclosure:
Unrealized gains on long-term investments recorded in other comprehensive (loss) income, net of deferred taxes of $17 and $30, respectively	27	$ 43
Reclassification from share-based liability compensation to equity	$ 401

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	6 Months Ended
	Oct. 27, 2012	Oct. 29, 2011
Consolidated Statements of Cash Flows
Unrealized gains on long-term investments recorded in other comprehensive income, net of deferred taxes	$ 17	$ 30

- Definition

This item represents the tax effects occurring during the period which are related to the net unrealized gain (loss) resulting from changes in the fair [carrying] value during the period of available-for-sale securities. Such tax affects would have been charged or credited directly to other comprehensive income or to related components of shareholders' equity.

+ References + Details

Organization and Significant Accounting Policies

6 Months Ended

Oct. 27, 2012

Organization and Significant Accounting Policies

Organization and Significant Accounting Policies

1. Organization and Significant Accounting Policies

Organization

AeroVironment, Inc., a Delaware corporation (the “Company”), is engaged in the design, development, production, support and operation of unmanned aircraft systems and efficient energy systems for various industries and governmental agencies.

Basis of Presentation

The accompanying unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial information and with the instructions of Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements. In the opinion of management, all adjustments, consisting only of normal recurring adjustments necessary for a fair presentation with respect to the interim financial statements have been included. The results of operations for the three and six months ended October 27, 2012 are not necessarily indicative of the results for the full year ending April 30, 2013. For further information, refer to the consolidated financial statements and footnotes thereto for the year ended April 30, 2012, included in the Company’s Annual Report on Form 10-K.

The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions, including estimates of anticipated contract costs and revenue utilized in the revenue recognition process, that affect the reported amounts in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates.

The Company’s consolidated financial statements include the assets, liabilities and operating results of wholly-owned subsidiaries. All significant intercompany accounts and transactions have been eliminated.

Segments

The Company’s products are sold and divided among two reportable segments to reflect the Company’s strategic goals. Operating segments are defined as components of an enterprise from which separate financial information is available that is evaluated regularly by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources and in assessing performance. The Company’s CODM is the Chief Executive Officer, who reviews the revenue and gross margin results for each of these segments in order to make resource allocation decisions, including the focus of research and development (“R&D”) activities and assessing performance. The Company’s reportable segments are business units that offer different products and services and are managed separately.

Investments

The Company’s investments are accounted for as held-to-maturity and available-for-sale and reported at amortized cost and fair value, respectively.

Fair Values of Financial Instruments

Fair values of cash and cash equivalents, accounts receivable, unbilled receivables, retentions and accounts payable approximate cost due to the short period of time to maturity.

Government Contracts

Payments to the Company on government cost reimbursable contracts are based on provisional, or estimated indirect rates, which are subject to an annual audit by the Defense Contract Audit Agency (“DCAA”). The cost audits result in the negotiation and determination of the final indirect cost rates that the Company may use for the period(s) audited. The final rates, if different from the provisional billing rates, may create an additional receivable or liability for the Company.

For example, during the course of its audits, the DCAA may question the Company’s incurred project costs, and if the DCAA believes the Company has accounted for such costs in a manner inconsistent with the requirements under Federal Acquisition Regulations, the DCAA auditor may recommend to the Company’s administrative contracting officer to disallow such costs. The Company can provide no assurance that the DCAA or other government audits will not result in material disallowances for incurred costs in the future.

Earnings Per Share

Basic earnings per share is computed using the weighted-average number of common shares outstanding, excluding shares of unvested restricted stock. The dilutive effect of potential common shares outstanding is included in diluted earnings per share and excludes any anti-dilutive effects of options, shares of unvested restricted stock and restricted stock units.

The reconciliation of basic to diluted shares is as follows:

	Three Months Ended		Six Months Ended
	October 27, 2012	October 29, 2011	October 27, 2012	October 29, 2011
Denominator for basic earnings per share:
Weighted average common shares outstanding, excluding unvested restricted stock	22,030,330	21,763,927	21,980,453	21,743,990
Dilutive effect of employee stock options, unvested restricted stock and restricted stock units	353,461	492,016	372,981	500,707
Denominator for diluted earnings per share	22,383,791	22,255,943	22,353,434	22,244,697

During the three and six months ended October 27, 2012 and October 29, 2011, certain shares reserved for issuance upon exercise of stock options, shares of unvested restricted stock and restricted stock units were not included in the computation of diluted earnings per share because their inclusion would have been anti-dilutive. The number of shares reserved for issuance upon exercise of stock options, shares of unvested restricted stock and restricted stock units that met this anti-dilutive criterion for the three months ended October 27, 2012 and October 29, 2011 was approximately 10,000 and 1,000, respectively. The number of shares reserved for issuance upon exercise of stock options, shares of unvested restricted stock and restricted stock units that met this anti-dilutive criterion for the six months ended October 27, 2012 and October 29, 2011 was approximately 5,000 and 2,000, respectively.

Recently Issued Accounting Standards

On May 1, 2012, the Company adopted changes in accordance with guidance issued by the Financial Accounting Standards Board (“FASB”), which requires companies to present the total of comprehensive income, the components of net income, and the components of other comprehensive income either in a single continuous statement of comprehensive income, or in two separate but consecutive statements. The Company elected to adopt the two-statement option. The new guidance eliminated the option to present the components of other comprehensive income as part of the statement of equity. Other than the change in presentation, the adoption of these changes had no material impact on the Company’s consolidated financial statements. The new guidance also required entities to present reclassification adjustments from accumulated other comprehensive income by component in both the statement in which net income is presented and the statement in which other comprehensive income is presented. However, in December 2011, the FASB issued guidance that indefinitely defers the guidance related to the presentation of reclassification adjustments.

On May 1, 2012, the Company adopted changes in accordance with guidance issued by the FASB to provide a consistent definition of fair value and to ensure that the fair value measurement and disclosure requirements are similar between U.S. generally accepted accounting principles and International Financial Reporting Standards. The new guidance changed certain fair value measurement principles and enhanced the disclosure requirements, particularly for Level 3 fair value measurements. The adoption of these changes did not have a material impact on the Company’s consolidated financial statements.

- Definition

The entire disclosure for the organization, consolidation and basis of presentation of financial statements disclosure, and significant accounting policies of the reporting entity. May be provided in more than one note to the financial statements, as long as users are provided with an understanding of (1) the significant judgments and assumptions made by an enterprise in determining whether it must consolidate a VIE and/or disclose information about its involvement with a VIE, (2) the nature of restrictions on a consolidated VIE's assets reported by an enterprise in its statement of financial position, including the carrying amounts of such assets, (3) the nature of, and changes in, the risks associated with an enterprise's involvement with the VIE, and (4) how an enterprise's involvement with the VIE affects the enterprise's financial position, financial performance, and cash flows. Describes procedure if disclosures are provided in more than one note to the financial statements.

+ References + Details

Investments

6 Months Ended

Oct. 27, 2012

Investments

Investments

2. Investments

Investments consist of the following (in thousands):

	October 27, 2012		April 30, 2012
Short-term investments:
Held-to-maturity securities:
Municipal securities	$	63,694	$	49,263
U.S. government securities	1,000		27,889
Total short-term investments	$	64,694	$	77,152
Long-term investments:
Held-to-maturity securities:
Municipal securities	$	58,808	$	52,261
Available-for-sale securities:
Auction rate securities	5,990		6,196
Total long-term investments	$	64,798	$	58,457

Held-To-Maturity Securities

At October 27, 2012 and April 30, 2012, the balance of held-to-maturity securities consisted of state and local government municipal securities and U.S. Treasury bills and notes. Interest earned from these investments is recorded in interest income.

The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the held-to-maturity investments as of October 27, 2012, were as follows (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses			Fair Value
Municipal securities	$	122,502	$	51	$	(25	)	$	122,528
U.S. government securities	1,000		—		—			1,000
Total held-to-maturity investments	$	123,502	$	51	$	(25	)	$	123,528

The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the held-to-maturity investments as of April 30, 2012, were as follows (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses			Fair Value
Municipal securities	$	101,524	$	48	$	(24	)	$	101,548
U.S. government securities	27,889		—		(1		)	27,888
Total held-to-maturity investments	$	129,413	$	48	$	(25	)	$	129,436

The amortized cost and fair value of the Company’s held-to-maturity securities by contractual maturity at October 27, 2012, were as follows (in thousands):

	Cost		Fair Value

Due within one year	$	64,694	$	64,709
Due after one year through three years	58,808		58,819
Total	$	123,502	$	123,528

Available-For-Sale Securities

As of October 27, 2012, the entire balance of available-for-sale securities consisted of four investment grade auction rate municipal bonds with maturities ranging from 7 to 22 years. These investments have characteristics similar to short-term investments, because at pre-determined intervals, generally ranging from 30 to 35 days, there is a new auction process at which the interest rates for these securities are reset to current interest rates. At the end of such period, the Company chooses to roll-over its holdings or redeem the investments for cash. A market maker facilitates the redemption of the securities and the underlying issuers are not required to redeem the investment within 365 days. Interest earned from these investments is recorded in interest income.

During the fourth quarter of the fiscal year ended April 30, 2008, the Company began experiencing failed auctions on some of its auction rate securities. A failed auction occurs when a buyer for the securities cannot be obtained and the market maker does not buy the security for its own account. The Company continues to earn interest on the investments that failed to settle at auction, at the maximum contractual rate until the next auction occurs. In the event the Company needs to access funds invested in these auction rate securities, the Company may not be able to liquidate these securities at the fair value recorded on October 27, 2012 until a future auction of these securities is successful or a buyer is found outside of the auction process.

As a result of the failed auctions, the fair values of these securities are estimated utilizing a discounted cash flow analysis as of October 27, 2012. The analysis considers, among other items, the collateralization underlying the security investments, the creditworthiness of the counterparty, the timing of expected future cash flows, and the estimated date upon which the security is expected to have a successful auction.

Based on the Company’s ability to access its cash and cash equivalents, expected operating cash flows, and other sources of cash, the Company does not anticipate the current lack of liquidity of these investments will affect its ability to operate the business in the ordinary course. The Company believes the current lack of liquidity of these investments is temporary and expects that the securities will be redeemed or refinanced at some point in the future. The Company will continue to monitor the value of its auction rate securities at each reporting period for a possible impairment if a further decline in fair value occurs. The auction rate securities have been in an unrealized loss position for more than 12 months. The Company has the ability and the intent to hold these investments until a recovery of fair value, which may be at maturity and as of October 27, 2012, the Company did not consider these investments to be other-than-temporarily impaired.

The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the available-for-sale investments as of October 27, 2012, were as follows (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses			Fair Value
Auction rate securities	$	7,100	$	—	$	(1,110	)	$	5,990
Total available-for-sale investments	$	7,100	$	—	$	(1,110	)	$	5,990

The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the available-for-sale investments as of April 30, 2012, were as follows (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses			Fair Value
Auction rate securities	$	7,350	$	—	$	(1,154	)	$	6,196
Total available-for-sale investments	$	7,350	$	—	$	(1,154	)	$	6,196

The amortized cost and fair value of the Company’s auction rate securities by contractual maturity at October 27, 2012, were as follows (in thousands):

	Cost		Fair Value

Due after five through 10 years	$	1,700	$	1,565
Due after 10 years	5,400		4,425
Total	$	7,100	$	5,990

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-Glossary Debt Security
-URI http://asc.fasb.org/extlink&oid=6509901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27290-111563

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-Glossary Equity Security
-URI http://asc.fasb.org/extlink&oid=6511694

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27232-111563

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27161-111563

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27405-111563

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 3, 19, 20, 21, 22, 137
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Inventories, net

6 Months Ended

Oct. 27, 2012

Inventories, net

Inventories, net

3. Inventories, net

Inventories consist of the following (in thousands):

	October 27, 2012			April 30, 2012
Raw materials	$	14,331		$	13,969
Work in process	5,830			7,390
Finished goods	28,026			24,934
Inventories, gross	48,187			46,293
Reserve for inventory obsolescence	(3,440		)	(2,754		)
Inventories, net	$	44,747		$	43,539

Fair Value Measurements

6 Months Ended

Oct. 27, 2012

Fair Value Measurements

Fair Value Measurements

4. Fair Value Measurements

Fair value is the price that would be received to sell an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy contains three levels as follows:

· Level 1 — Inputs to the valuation based upon quoted prices (unadjusted) for identical assets or liabilities in active markets that are accessible as of the measurement date.

· Level 2 — Inputs to the valuation include quoted prices in either markets that are not active, or in active markets for similar assets or liabilities, inputs other than quoted prices that are observable, and inputs that are derived principally from or corroborated by observable market data.

· Level 3 — Inputs to the valuation that are unobservable inputs for the asset or liability.

The Company’s financial assets measured at fair value on a recurring basis at October 27, 2012, were as follows (in thousands):

	Fair Value Measurement Using
Description	Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)		Total
Auction rate securities	$	—	$	—	$	5,990	$	5,990
Total	$	—	$	—	$	5,990	$	5,990

Due to the auction failures of the Company’s auction rate securities that began in the fourth quarter of fiscal 2008, there are still no quoted prices in active markets for identical assets as of October 27, 2012. Therefore, the Company has classified its auction rate securities as Level 3 financial assets. The following table provides a reconciliation between the beginning and ending balances of items measured at fair value on a recurring basis in the table above that used significant unobservable inputs (Level 3) (in thousands):

	Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Description	Auction Rate Securities
Balance at April 30, 2012	$	6,196
Transfers to Level 3	—
Total gains (realized or unrealized)
Included in earnings	—
Included in other comprehensive income	44
Purchases, issuances and settlements, net	(250		)
Balance at October 27, 2012	$	5,990
The amount of total gains or (losses) for the period included in earnings (or change in net assets) attributable to the change in unrealized gains or losses relating to assets still held at October 27, 2012	$	—

The auction rate securities are valued using a discounted cash flow model. The analysis considers, among other items, the collateralization underlying the security investments, the creditworthiness of the counterparty, the timing of expected future cash flows, and the estimated date upon which the security is expected to have a successful auction. As of October 27, 2012, the inputs used in the Company’s discounted cash flow analysis included current coupon rates ranging from 0.3% to 0.6%, estimated redemption periods of 7 to 22 years and discount rates of 7.7% to 18.9%. The discount rates were based on market rates for municipal bond securities, as adjusted for a risk premium to reflect the lack of liquidity of these investments. Assuming a higher discount rate, a longer estimated redemption period and lower coupon rates would result in a lower fair market value. Conversely, assuming a lower discount rate, a shorter estimated redemption period and higher coupon rates would result in a higher fair market value.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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-Name Accounting Standards Codification
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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15B
-Subparagraph a, b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Number 159
-Paragraph 17-22, 27, 28
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Warranty Reserves

6 Months Ended

Oct. 27, 2012

Warranty Reserves

Warranty Reserves

5. Warranty Reserves

The Company accrues an estimate of its exposure to warranty claims based upon both current and historical product sales data and warranty costs incurred. The warranty reserve is included in other current liabilities. The related expense is included in cost of sales. Warranty reserve activity is summarized as follows for the three and six months ended October 27, 2012 and October 29, 2011 (in thousands):

	Three Months Ended						Six Months Ended
	October 27,			October 29,			October 27,			October 29,
	2012			2011			2012			2011

Beginning balance	$	2,633		$	1,046		$	2,872		$	1,127
Warranty expense	678			900			1,208			1,252
Warranty claims settled	(2,052		)	(602		)	(2,821		)	(1,035		)
Ending balance	$	1,259		$	1,344		$	1,259		$	1,344

Customer-Funded Research & Development

6 Months Ended

Oct. 27, 2012

Customer-Funded Research & Development

Customer-Funded Research & Development

6. Customer-Funded Research & Development

Customer-funded R&D costs are incurred pursuant to contracts (revenue arrangements) to perform R&D activities according to customer specifications. These costs are direct contract costs and are expensed to cost of sales when the corresponding revenue is recognized, which is generally as the R&D services are performed. Revenue from customer-funded R&D was approximately $10.4 million and $17.0 million for the three and six months ended October 27, 2012, respectively. Revenue from customer-funded R&D was approximately $4.0 million and $9.2 million for the three and six months ended October 29, 2011, respectively.

- Definition

The entire disclosure for research, development, and computer software activities, including contracts and arrangements to be performed for others and with federal government. Includes costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility and in-process research and development acquired in a business combination consummated during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 1
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Audit and Accounting Guide (AAG)
-Number AAG-FGC
-Paragraph 56, 57
-IssueDate 2006-05-01
-Chapter 3
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Income Taxes

6 Months Ended

Oct. 27, 2012

Income Taxes

Income Taxes

7. Income Taxes

For the three and six months ended October 27, 2012, the Company recorded a provision for income taxes of $4.5 million and $3.8 million, respectively, yielding an effective tax rate of 34.0% and 34.1%, respectively. For the three and six months ended October 29, 2011, the Company recorded a provision for income taxes of $3.1 million and $3.3 million, respectively, yielding an effective tax rate of 32.0% and 32.1%, respectively. The variance from statutory rates for the three and six months ended October 29, 2011 was primarily due to research and development tax credits.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h))
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Article 4

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Segment Data

6 Months Ended

Oct. 27, 2012

Segment Data

Segment Data

8. Segment Data

The Company’s product segments are as follows:

· Unmanned Aircraft Systems (“UAS”) — The UAS segment focuses primarily on the design, development, production, support and operation of innovative UAS that provide situational awareness and other mission effects to increase the security and operational effectiveness of the Company’s customers.

· Efficient Energy Systems (“EES”) — The EES segment focuses primarily on the design, development, production, support and operation of innovative efficient electric energy systems that address the growing demand for electric transportation solutions.

The accounting policies of the segments are the same as those described in Note 1, “Organization and Significant Accounting Policies.” The operating segments do not make sales to each other. Depreciation and amortization related to the manufacturing of goods is included in gross margin for the segments. The Company does not discretely allocate assets to its operating segments, nor does the CODM evaluate operating segments using discrete asset information. Consequently, the Company operates its financial systems as a single segment for accounting and control purposes, maintains a single indirect rate structure across all segments, has no inter-segment sales or corporate elimination transactions, and maintains limited financial statement information by segment.

The segment results are as follows (in thousands):

	Three Months Ended				Six Months Ended
	October 27,		October 29,		October 27,		October 29,
	2012		2011		2012		2011
Revenue:
UAS	$	65,433	$	66,931	$	114,239	$	119,136
EES	14,845		13,441		24,716		23,233
Total	80,278		80,372		138,955		142,369
Cost of sales:
UAS	35,279		39,707		68,035		71,707
EES	9,363		10,035		15,779		18,317
Total	44,642		49,742		83,814		90,024
Gross margin:
UAS	30,154		27,224		46,204		47,429
EES	5,482		3,406		8,937		4,916
Total	35,636		30,630		55,141		52,345
Selling, general and administrative	13,176		12,240		26,797		25,940
Research and development	9,386		8,816		17,522		16,402
Income from operations	13,074		9,574		10,822		10,003
Interest income	162		106		334		184
Income before income taxes	$	13,236	$	9,680	$	11,156	$	10,187

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Organization and Significant Accounting Policies (Policies)

6 Months Ended

Oct. 27, 2012

Organization and Significant Accounting Policies

Basis of Presentation

Basis of Presentation

Segments

Segments

Investments

Investments

The Company’s investments are accounted for as held-to-maturity and available-for-sale and reported at amortized cost and fair value, respectively.

Fair Values of Financial Instruments

Fair Values of Financial Instruments

Fair values of cash and cash equivalents, accounts receivable, unbilled receivables, retentions and accounts payable approximate cost due to the short period of time to maturity.

Government Contracts

Government Contracts

Earnings Per Share

Earnings Per Share

The reconciliation of basic to diluted shares is as follows:

	Three Months Ended		Six Months Ended
	October 27, 2012	October 29, 2011	October 27, 2012	October 29, 2011
Denominator for basic earnings per share:
Weighted average common shares outstanding, excluding unvested restricted stock	22,030,330	21,763,927	21,980,453	21,743,990
Dilutive effect of employee stock options, unvested restricted stock and restricted stock units	353,461	492,016	372,981	500,707
Denominator for diluted earnings per share	22,383,791	22,255,943	22,353,434	22,244,697

Recently Issued Accounting Standards

Recently Issued Accounting Standards

- Definition

Disclosure of accounting policy for computing basic and diluted earnings or loss per share for each class of common stock and participating security. Addresses all significant policy factors, including any antidilutive items that have been excluded from the computation and takes into account stock dividends, splits and reverse splits that occur after the balance sheet date of the latest reporting period but before the issuance of the financial statements.

+ References + Details

- Definition

Disclosure of accounting policy for investments in debt and equity securities that have readily determinable fair values (marketable securities). At a minimum, the disclosure might address accounting policies for investments classified as trading, available for sale, or held to maturity and may include how the entity determines whether impairments of available for sale or held to maturity investments are other than temporary, how the fair values of the entity's securities are determined, and the entity's accounting treatment for transfers between investment categories.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-SubTopic 10
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-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 7-16
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-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 5
-Section M

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 2, 12
-Article 5

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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 10, 11
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Organization and Significant Accounting Policies (Tables)

6 Months Ended

Oct. 27, 2012

Organization and Significant Accounting Policies

Schedule of reconciliation of basic to diluted shares

	Three Months Ended		Six Months Ended
	October 27, 2012	October 29, 2011	October 27, 2012	October 29, 2011
Denominator for basic earnings per share:
Weighted average common shares outstanding, excluding unvested restricted stock	22,030,330	21,763,927	21,980,453	21,743,990
Dilutive effect of employee stock options, unvested restricted stock and restricted stock units	353,461	492,016	372,981	500,707
Denominator for diluted earnings per share	22,383,791	22,255,943	22,353,434	22,244,697

Investments (Tables)

6 Months Ended

Oct. 27, 2012

Investments

Schedule of investments

Investments consist of the following (in thousands):

	October 27, 2012		April 30, 2012
Short-term investments:
Held-to-maturity securities:
Municipal securities	$	63,694	$	49,263
U.S. government securities	1,000		27,889
Total short-term investments	$	64,694	$	77,152
Long-term investments:
Held-to-maturity securities:
Municipal securities	$	58,808	$	52,261
Available-for-sale securities:
Auction rate securities	5,990		6,196
Total long-term investments	$	64,798	$	58,457

Schedule of amortized cost, gross unrealized gains, gross unrealized losses and estimated fair value of securities held-to-maturity

The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the held-to-maturity investments as of October 27, 2012, were as follows (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses			Fair Value
Municipal securities	$	122,502	$	51	$	(25	)	$	122,528
U.S. government securities	1,000		—		—			1,000
Total held-to-maturity investments	$	123,502	$	51	$	(25	)	$	123,528

The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the held-to-maturity investments as of April 30, 2012, were as follows (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses			Fair Value
Municipal securities	$	101,524	$	48	$	(24	)	$	101,548
U.S. government securities	27,889		—		(1		)	27,888
Total held-to-maturity investments	$	129,413	$	48	$	(25	)	$	129,436

Schedule of amortized cost, gross unrealized gains, gross unrealized losses and estimated fair value of available-for-sale investments

The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the available-for-sale investments as of October 27, 2012, were as follows (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses			Fair Value
Auction rate securities	$	7,100	$	—	$	(1,110	)	$	5,990
Total available-for-sale investments	$	7,100	$	—	$	(1,110	)	$	5,990

The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the available-for-sale investments as of April 30, 2012, were as follows (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses			Fair Value
Auction rate securities	$	7,350	$	—	$	(1,154	)	$	6,196
Total available-for-sale investments	$	7,350	$	—	$	(1,154	)	$	6,196

Held-to-maturity securities

Investments

Schedule of amortized cost and fair value by contractual maturity

The amortized cost and fair value of the Company’s held-to-maturity securities by contractual maturity at October 27, 2012, were as follows (in thousands):

	Cost		Fair Value

Due within one year	$	64,694	$	64,709
Due after one year through three years	58,808		58,819
Total	$	123,502	$	123,528

Available-for-sale securities

Investments

Schedule of amortized cost and fair value by contractual maturity

The amortized cost and fair value of the Company’s auction rate securities by contractual maturity at October 27, 2012, were as follows (in thousands):

	Cost		Fair Value

Due after five through 10 years	$	1,700	$	1,565
Due after 10 years	5,400		4,425
Total	$	7,100	$	5,990

- Definition

Tabular disclosure of all investments in certain debt and equity securities for which the entity has the positive intent and ability to hold until maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27405-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27232-111563

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62586-112803

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27337-111563

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=6435544&loc=d3e41834-113960

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5086-111524

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 137
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Inventories, net (Tables)

6 Months Ended

Oct. 27, 2012

Inventories, net

Schedule of inventories

Inventories consist of the following (in thousands):

	October 27, 2012			April 30, 2012
Raw materials	$	14,331		$	13,969
Work in process	5,830			7,390
Finished goods	28,026			24,934
Inventories, gross	48,187			46,293
Reserve for inventory obsolescence	(3,440		)	(2,754		)
Inventories, net	$	44,747		$	43,539

Fair Value Measurements (Tables)

6 Months Ended

Oct. 27, 2012

Fair Value Measurements

Schedule of financial assets measured at fair value on a recurring basis

The Company’s financial assets measured at fair value on a recurring basis at October 27, 2012, were as follows (in thousands):

	Fair Value Measurement Using
Description	Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)		Total
Auction rate securities	$	—	$	—	$	5,990	$	5,990
Total	$	—	$	—	$	5,990	$	5,990

Schedule of reconciliation between beginning and ending balances of items measured at fair value on recurring basis

The following table provides a reconciliation between the beginning and ending balances of items measured at fair value on a recurring basis in the table above that used significant unobservable inputs (Level 3) (in thousands):

	Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Description	Auction Rate Securities
Balance at April 30, 2012	$	6,196
Transfers to Level 3	—
Total gains (realized or unrealized)
Included in earnings	—
Included in other comprehensive income	44
Purchases, issuances and settlements, net	(250		)
Balance at October 27, 2012	$	5,990
The amount of total gains or (losses) for the period included in earnings (or change in net assets) attributable to the change in unrealized gains or losses relating to assets still held at October 27, 2012	$	—

- Definition

Tabular disclosure of assets, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, by class that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3).

+ References + Details

- Definition

Tabular disclosure of the fair value measurement of assets using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets) and gains or losses recognized in other comprehensive income (loss), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset.

+ References + Details

Warranty Reserves (Tables)

6 Months Ended

Oct. 27, 2012

Warranty Reserves

Summary of warranty reserve activity

Warranty reserve activity is summarized as follows for the three and six months ended October 27, 2012 and October 29, 2011

(in thousands):

	Three Months Ended						Six Months Ended
	October 27,			October 29,			October 27,			October 29,
	2012			2011			2012			2011

Beginning balance	$	2,633		$	1,046		$	2,872		$	1,127
Warranty expense	678			900			1,208			1,252
Warranty claims settled	(2,052		)	(602		)	(2,821		)	(1,035		)
Ending balance	$	1,259		$	1,344		$	1,259		$	1,344

Segment Data (Tables)

6 Months Ended

Oct. 27, 2012

Segment Data

Schedule of segment results

The segment results are as follows (in thousands):

	Three Months Ended				Six Months Ended
	October 27,		October 29,		October 27,		October 29,
	2012		2011		2012		2011
Revenue:
UAS	$	65,433	$	66,931	$	114,239	$	119,136
EES	14,845		13,441		24,716		23,233
Total	80,278		80,372		138,955		142,369
Cost of sales:
UAS	35,279		39,707		68,035		71,707
EES	9,363		10,035		15,779		18,317
Total	44,642		49,742		83,814		90,024
Gross margin:
UAS	30,154		27,224		46,204		47,429
EES	5,482		3,406		8,937		4,916
Total	35,636		30,630		55,141		52,345
Selling, general and administrative	13,176		12,240		26,797		25,940
Research and development	9,386		8,816		17,522		16,402
Income from operations	13,074		9,574		10,822		10,003
Interest income	162		106		334		184
Income before income taxes	$	13,236	$	9,680	$	11,156	$	10,187

- Definition

Tabular disclosure of the profit or loss and total assets for each reportable segment. An entity discloses certain information on each reportable segment if the amounts (a) are included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) are otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.

+ References + Details

Organization and Significant Accounting Policies (Details)	3 Months Ended		6 Months Ended
	Oct. 27, 2012 shares	Oct. 29, 2011 shares	Oct. 27, 2012 Item shares	Oct. 29, 2011 shares
Segments
Number of reportable segments \| Item			2
Denominator for basic earnings per share:
Weighted average common shares outstanding, excluding unvested restricted stock (in shares)	22,030,330	21,763,927	21,980,453	21,743,990
Dilutive effect of employee stock options, unvested restricted stock and restricted stock units (in shares)	353,461	492,016	372,981	500,707
Denominator for diluted earnings per share	22,383,791	22,255,943	22,353,434	22,244,697
Anti-dilutive stock options, shares of unvested restricted stock and restricted stock units	10,000	1,000	5,000	2,000

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Antidilution
-URI http://asc.fasb.org/extlink&oid=6505113

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Diluted Earnings Per Share
-URI http://asc.fasb.org/extlink&oid=6510752

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Contingent Stock Agreement
-URI http://asc.fasb.org/extlink&oid=6508534

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 40
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 13, 14
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 07-4
-Paragraph 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 171
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References + Details

- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1448-109256

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Weighted-Average Number of Common Shares Outstanding
-URI http://asc.fasb.org/extlink&oid=6528421

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 07-4
-Paragraph 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 8
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 171
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 40
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Investments (Details) $ in Thousands	6 Months Ended
Investments (Details) $ in Thousands	Oct. 27, 2012 USD ($) Item	Apr. 30, 2012 USD ($)
Short-term investments:
Total short-term investments	$ 64,694	$ 77,152
Long-term investments:
Total long-term investments	64,798	58,457
Held-To-Maturity Securities
Amortized Cost	123,502	129,413
Gross Unrealized Gains	51	48
Gross Unrealized Losses	(25)	(25)
Fair Value	123,528	129,436
Amortized cost of held-to-maturity securities by contractual maturities
Due within one year	64,694
Due after one year through three years	58,808
Total	123,502
Fair value of held-to-maturity securities by contractual maturities
Due within one year	64,709
Due after one year through three years	58,819
Total	123,528
Available-For-Sale Securities
Amortized Cost	7,100	7,350
Gross Unrealized Losses	(1,110)	(1,154)
Total	5,990	6,196
Fair value of available-for-sale securities by contractual maturities
Total	5,990	6,196
Municipal securities
Held-To-Maturity Securities
Amortized Cost	122,502	101,524
Gross Unrealized Gains	51	48
Gross Unrealized Losses	(25)	(24)
Fair Value	122,528	101,548
U.S. government securities
Held-To-Maturity Securities
Amortized Cost	1,000	27,889
Gross Unrealized Losses		(1)
Fair Value	$ 1,000	27,888
Auction rate securities
Available-For-Sale Securities
Number of available-for-sale securities \| Item	4
Available-For-Sale Securities
Amortized Cost	$ 7,100	7,350
Gross Unrealized Losses	(1,110)	(1,154)
Total	5,990	6,196
Amortized cost of available-for-sale securities by contractual maturities
Due after five through 10 years	1,700
Due after 10 years	5,400
Total	7,100
Fair value of available-for-sale securities by contractual maturities
Due after five through 10 years	1,565
Due after 10 years	4,425
Total	$ 5,990	6,196
Auction rate securities \| Minimum
Available-For-Sale Securities
Maturity period of available-for-sale securities	7 years
Pre-determined interval to reset interest rates to current rates	30 days
Auction rate securities \| Maximum
Available-For-Sale Securities
Maturity period of available-for-sale securities	22 years
Pre-determined interval to reset interest rates to current rates	35 days
Period for which the issuer of securities is not required to redeem the securities	365 days
Held-to-maturity securities \| Municipal securities
Short-term investments:
Total short-term investments	$ 63,694	49,263
Long-term investments:
Total long-term investments	58,808	52,261
Held-to-maturity securities \| U.S. government securities
Short-term investments:
Total short-term investments	1,000	27,889
Available-for-sale securities \| Auction rate securities
Long-term investments:
Total long-term investments	$ 5,990	$ 6,196

Inventories, net (Details) - USD ($) $ in Thousands	Oct. 27, 2012	Apr. 30, 2012
Inventories, net
Raw materials	$ 14,331	$ 13,969
Work in process	5,830	7,390
Finished goods	28,026	24,934
Inventories, gross	48,187	46,293
Reserve for inventory obsolescence	(3,440)	(2,754)
Inventories, net	$ 44,747	$ 43,539

- Definition

The amount of the valuation account as of the balance sheet date which reduces the carrying amount of inventory to net realizable value; takes into consideration such factors as market value, excessive quantities based on expected sales, technological obsolescence, and shrinkage. May also provide for estimated product returns or price concessions pertaining to product cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.BB)
-URI http://asc.fasb.org/extlink&oid=6386940&loc=d3e100047-122729

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e24092-122690

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6386567&loc=d3e3927-108312

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Paragraph 14
-Chapter 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Paragraph 8, 9, 14
-Chapter 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Section A
-Paragraph 9
-Chapter 3
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 09
-Article 12

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 6
-Subparagraph a
-Article 5

+ Details

Fair Value Measurements (Details) - Recurring basis $ in Thousands	Oct. 27, 2012 USD ($)
Significant unobservable inputs (Level 3)
Fair Value Measurement
Available-for-sale securities	$ 5,990
Significant unobservable inputs (Level 3) \| Auction rate securities
Fair Value Measurement
Available-for-sale securities	5,990
Total Fair Value
Fair Value Measurement
Available-for-sale securities	5,990
Total Fair Value \| Auction rate securities
Fair Value Measurement
Available-for-sale securities	$ 5,990

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References + Details

Fair Value Measurements (Details 2) - Auction rate securities $ in Thousands	6 Months Ended
	Oct. 27, 2012 USD ($)
Reconciliation between beginning and ending balances of items measured at fair value on recurring basis
Balance at the beginning of the period	$ 6,196
Total gains (realized or unrealized)
Included in other comprehensive income	44
Purchases, issuances and settlements, net	(250)
Balance at the end of the period	$ 5,990

Fair Value Measurements (Details 3) $ in Millions	6 Months Ended
Fair Value Measurements (Details 3) $ in Millions	Oct. 27, 2012 USD ($)
Auction rate securities
Fair Value Inputs
Original cost of investments	$ 7.1
Significant unobservable inputs (Level 3) \| Discounted cash flow \| Minimum
Fair Value Inputs
Coupon rates (as a percent)	0.30%
Estimated redemption period	7 years
Discount rates (as a percent)	7.70%
Significant unobservable inputs (Level 3) \| Discounted cash flow \| Maximum
Fair Value Inputs
Coupon rates (as a percent)	0.60%
Estimated redemption period	22 years
Discount rates (as a percent)	18.90%

Warranty Reserves (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Warranty Reserves (Details) - USD ($) $ in Thousands	Oct. 27, 2012	Oct. 29, 2011	Oct. 27, 2012	Oct. 29, 2011
Warranty Reserves
Beginning balance			$ 2,872	$ 1,127
Warranty expense	$ 678	$ 900	1,208	1,252
Warranty claims settled	(2,052)	(602)	(2,821)	(1,035)
Ending balance	$ 1,259	$ 1,344	$ 1,259	$ 1,344

Customer-Funded Research & Development (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Oct. 27, 2012	Oct. 29, 2011	Oct. 27, 2012	Oct. 29, 2011
Customer-Funded Research & Development
Revenue from customer-funded R&D	$ 10.4	$ 4.0	$ 17.0	$ 9.2

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Oct. 27, 2012	Oct. 29, 2011	Oct. 27, 2012	Oct. 29, 2011
Income Taxes
Provision for income taxes	$ 4,498	$ 3,093	$ 3,804	$ 3,274
Effective tax rate (as a percent)	34.00%	32.00%	34.10%	32.10%

Segment Data (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Segment Data (Details) - USD ($) $ in Thousands	Oct. 27, 2012	Oct. 29, 2011	Oct. 27, 2012	Oct. 29, 2011
Revenue:
Total revenue	$ 80,278	$ 80,372	$ 138,955	$ 142,369
Cost of sales:
Total cost of sales	44,642	49,742	83,814	90,024
Gross margin:
Gross margin	35,636	30,630	55,141	52,345
Selling, general and administrative	13,176	12,240	26,797	25,940
Research and development	9,386	8,816	17,522	16,402
Income from operations	13,074	9,574	10,822	10,003
Interest income	162	106	334	184
Income before income taxes	13,236	9,680	11,156	10,187
UAS
Revenue:
Total revenue	65,433	66,931	114,239	119,136
Cost of sales:
Total cost of sales	35,279	39,707	68,035	71,707
Gross margin:
Gross margin	30,154	27,224	46,204	47,429
EES
Revenue:
Total revenue	14,845	13,441	24,716	23,233
Cost of sales:
Total cost of sales	9,363	10,035	15,779	18,317
Gross margin:
Gross margin	5,482	3,406	8,937	4,916
Unallocated to segment
Gross margin:
Selling, general and administrative	13,176	12,240	26,797	25,940
Research and development	9,386	8,816	17,522	16,402
Income from operations	13,074	9,574	10,822	10,003
Interest income	162	106	334	184
Income before income taxes	$ 13,236	$ 9,680	$ 11,156	$ 10,187

Label	Element	Value
Standard Product Warranty Accrual	us-gaap_StandardProductWarrantyAccrual	$ 2,633,000
Standard Product Warranty Accrual	us-gaap_StandardProductWarrantyAccrual	$ 1,046,000