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 December 31,
	2014			2013
Balance at beginning of period	$	1,577		$	572
Bad debt expense/(recovery)		283			15
Uncollectible accounts written off, net of recoveries		(2	)		88
Change in foreign currency translation		(14	)		(2	)
Balance at end of period	$	1,844		$	673

Inventories:

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

	December 31,			September 30,
	2014			2014
Raw materials, parts and subassemblies	$	40,017		$	35,349
Work-in-progress		1,495			2,035
Provision for excess and obsolete inventory		(4,882	)		(4,569	)
Total inventories	$	36,630		$	32,815

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):

	December 31,			September 30,
	2014			2014
Costs incurred on uncompleted contracts	$	611,852		$	604,939
Estimated earnings		155,112			157,562
		766,964			762,501
Less: Billings to date		(741,322	)		(715,233	)
Net underbilled position	$	25,642		$	47,268

Included in the accompanying balance sheets under the following captions:
Costs and estimated earnings in excess of billings on uncompleted contracts - underbilled	$	84,922		$	95,970
Billings in excess of costs and estimated earnings on uncompleted contracts - overbilled		(59,280	)		(48,702	)
Net underbilled position	$	25,642		$	47,268

Warranty Accrual

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

	Three months ended December 31,
	2014			2013
Balance at beginning of period	$	4,557		$	5,282
Increase to warranty expense		537			464
Deduction for warranty charges		(524	)		(731	)
Increase (decrease) due to foreign currency translations		(90	)		(5	)
Balance at end of period	$	4,480		$	5,010