Combined environment reliability test /CERT/ for avionics subsystems

The paper presents the initial experimental results of the combined environments reliability test (CERT) for flight-simulating avionics equipment. The reliability test duplicates flight environmental conditions on a one-to-one basis with the specific aircraft mission profile. This approach is commonly referred to as environmental profile or flight profile testing. The test profile for each environment (temperature, altitude, humidity, vibration, etc.) is developed by defining the principal aircraft missions in terms of Mach number, engine RPM, and aircraft altitude vs flight time. The avionics item selected for initial evaluation of the CERT method was a multi-mode dual-channel radar subsystem currently deployed in high performance aircraft. A specified MTBF of 98 hours of radar subsystem operation was required to be verified by the reliability test. The test facility consisted of a 4 ft diameter, 5 ft long cylindrical test chamber with capability for combined simulation of bay temperature, altitude, vibration and forced air environments.