C. DETAIL OF SELECTED BALANCE SHEET ACCOUNTS

Allowance for Doubtful Accounts

Activity in our allowance for doubtful accounts receivable consisted of the following (in thousands):

	Three Months Ended						Six Months Ended
	March 31,						March 31,
	2014			2013			2014			2013
Balance at beginning of period	$	673		$	928		$	572		$	1,297
Bad debt recovery		(170	)		(59	)		(60	)		(380	)
Uncollectible accounts written off, net of recoveries		—			(28	)		(9	)		(85	)
Change in foreign currency translation		(2	)		(23	)		(2	)		(14	)
Balance at end of period	$	501		$	818		$	501		$	818

Inventories:

The components of inventories are summarized below (in thousands):

	March 31,			September 30,
	2014			2013
Raw materials, parts and subassemblies	$	29,758		$	30,077
Work-in-progress		3,771			3,818
Provision for excess and obsolete inventory		(4,099	)		(4,932	)
Total inventories	$	29,430		$	28,963

Cost and Estimated Earnings on Uncompleted Contracts

The components of costs and estimated earnings and related amounts billed on uncompleted contracts are summarized below (in thousands):

	March 31,			September 30,
	2014			2013
Costs incurred on uncompleted contracts	$	685,257		$	618,570
Estimated earnings		172,948			159,962
		858,205			778,532
Less: Billings to date		(820,707	)		(747,446	)
Net underbilled position	$	37,498		$	31,086

Included in the accompanying balance sheets under the following captions:
Costs and estimated earnings in excess of billings on uncompleted contracts – underbilled	$	79,517		$	79,420
Billings in excess of costs and estimated earnings on uncompleted contracts – overbilled		(42,019	)		(48,334	)
Net underbilled position	$	37,498		$	31,086

Warranty Accrual

Activity in our product warranty accrual consisted of the following (in thousands):

	Three Months Ended						Six Months Ended
	March 31,						March 31,
	2014			2013			2014			2013
Balance at beginning of period	$	5,010		$	5,610		$	5,282		$	5,548
Increase to warranty expense		1,042			810			1,505			1,495
Deduction for warranty charges		(1,196	)		(1,230	)		(1,926	)		(1,851	)
Increase (decrease) due to foreign currency translations		(23	)		(81	)		(28	)		(83	)
Balance at end of period	$	4,833		$	5,109		$	4,833		$	5,109