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 March 31,						Six months ended March 31,
	2017			2016			2017			2016
Balance at beginning of period	$	664		$	1,010		$	811		$	746
Bad debt expense (recovery)	16			92			(97		)	339
Uncollectible accounts written off, net of recoveries	(373		)	(141		)	(400		)	(114		)
Change due to foreign currency translation	3			15			(4		)	5
Balance at end of period	$	310		$	976		$	310		$	976

Inventories

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



	March 31, 2017		September 30, 2016
Raw materials, parts and subassemblies, net	$	19,760	$	25,525
Work-in-progress	602		996
Total inventories	$	20,362	$	26,521

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, 2017			September 30, 2016
Costs incurred on uncompleted contracts	$	770,679		$	1,088,921
Estimated earnings	245,832			350,125
	1,016,511			1,439,046
Less: Billings to date	(992,432		)	(1,416,914		)
Net underbilled position	$	24,079		$	22,132
Included in the accompanying balance sheets under the following captions:
Costs and estimated earnings in excess of billings on uncompleted contracts – underbilled	$	56,618		$	66,106
Billings in excess of costs and estimated earnings on uncompleted contracts – overbilled	(32,539		)	(43,974		)
Net underbilled position	$	24,079		$	22,132

Accrued Product Warranty

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



	Three months ended March 31,						Six months ended March 31,
	2017			2016			2017			2016
Balance at beginning of period	$	4,230		$	5,105		$	4,639		$	4,930
Increase to warranty expense	349			832			719			2,158
Deduction for warranty charges	(944		)	(1,175		)	(1,669		)	(2,275		)
Change due to foreign currency translation	14			25			(40		)	(26		)
Balance at end of period	$	3,649		$	4,787		$	3,649		$	4,787