Note 3 - Business Combinations - Assets Acquired and Liabilities Assumed by AirCo (Details) - USD ($)		3 Months Ended
	May 02, 2017	Jun. 30, 2018	Jun. 30, 2017
Consideration paid		$ 3,325,700	$ 2,900,000
AirCo [Member] | Acquired Inventory and Principal Business Assets, and Assumed Specified Liabilities, of Aircraft Instrument and Radio Company, Incorporated, and Aircraft Instrument and Radio Services, Inc. [Member]
Accounts receivables	$ 748,936
Inventories	3,100,000
Property and equipment	26,748
Accounts payable	(313,117)
Accrued expenses	(382,687)
Net assets acquired	3,179,880
Consideration paid	2,400,000
Bargain purchase gain	$ 779,880