COSTS AND ESTIMATED EARNINGS IN EXCESS OF BILLINGS, NET (Details) - USD ($)	3 Months Ended		6 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
COSTS AND ESTIMATED EARNINGS IN EXCESS OF BILLINGS, NET (Details) [Line Items]
Revenues	$ 12,936,000	$ 13,990,000	$ 25,890,000	$ 26,940,000
Loss on Contracts	31,000	121,000	47,000	731,000
Contracts Accounted for under Percentage of Completion [Member]
COSTS AND ESTIMATED EARNINGS IN EXCESS OF BILLINGS, NET (Details) [Line Items]
Revenues	$ 12,200,000	$ 12,900,000	$ 24,600,000	$ 24,600,000