Note 11 - Industry Segmentation and Sales by Major Customer - Schedule of Revenue by Major Customers by Reporting Segments (Details) - Customer Concentration Risk [Member] - Sales Revenue, Net [Member]	12 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Top Customer [Member]
Concentration risk percentage	12.30%
Aerospace Products [Member] | Top Customer [Member]
Concentration risk percentage	12.30%	10.50%
Professional Services [Member]
Concentration risk percentage