Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Bombardier, Inc., Model BD-700-2A12 airplanes. This proposed AD was prompted by a report indicating that the fan in a transformer rectifier unit (TRU) can become inoperative in a manner that is not detectable by the fan monitoring circuit. This proposed AD would require replacement of the existing TRU Number 2 with a new part number that incorporates a correction to the fan and the monitoring circuit. This proposed AD would also prohibit the installation of affected parts. The FAA is proposing this AD to address the unsafe condition on these products.