Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
Two cases have been reported in which the ADG [air driven generator] has failed to power the essential bus following in-flight deployment as part of its periodic operational check. Subsequent inspection revealed that the ADG power feeder harness wire (* * * aromatic polyimide) had chafed on the backshell of its own connector (P1XC), resulting in a short circuit, wire damage and disconnection of the wire from the ADG. Coupled with a dual generator failure, such a disconnection would result in the loss of emergency power to critical systems, with a consequent adverse effect on the controllability of the aircraft. * * * * *
The proposed ADwould require actions that are intended to address the unsafe condition described in the MCAI.