MIL-C-27298, MILITARY SPECIFICATION: CLOCK, AIRCRAFT, MECHANICAL, ABU-9-A (03 JUL 1980)., This specification covers one type of elapsed mechanical aircraft clock

MIL-C-27298, MILITARY SPECIFICATION: CLOCK, AIRCRAFT, MECHANICAL, ABU-9-A (03 JUL 1980)., This specification covers one type of elapsed mechanical aircraft clock.