Inventories (Tables)

9 Months Ended

12 Months Ended

Jan. 31, 2013

Apr. 30, 2012

Schedule of Inventory

	January 31, 2013			April 30, 2012
Work-in-progress for maintenance contracts under completed contract accounting	$	4,366		$	3,951
Consumables		111,926			96,588
Provision for obsolescence		(10,518	)		(10,526	)
	$	105,774		$	90,013

	2012			2011
Work-in-progress for long-term maintenance contracts under completed contract accounting	$	3,951		$	5,989
Consumables		96,588			105,713
Provision for obsolescence		(10,526	)		(9,478	)
	$	90,013		$	102,224