COSTS AND ESTIMATED EARNINGS ON UNCOMPLETED CONTRACTS (Details Textual) (USD $)	3 Months Ended		9 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2013	Jan. 31, 2012	Apr. 30, 2012
Increase In Gross Profit	$ 349,000		$ 1,679,000
Increase In Gross Profit Per Share	$ 0.05		$ 0.24
Decrease In Gross Profit		4,785,000		3,108,000
Decrease In Gross Profit Per Share		$ 0.69		$ 0.45
Provision for loss on uncompleted contracts	46,485	1,015,465	46,485	1,015,465	1,886,896
Trenton Operations [Member]
Increase In Gross Profit			1,486,000
Cumulative-Effect Adjustment, Gross Losses				$ 5,000,000