Airworthiness Directives; The Boeing Company Airplanes

FAA / Federal Register · 2021-27974

The FAA proposes to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 747-400 series airplanes. This proposed AD was prompted by a report that after a certain circuit breaker tripped, power to the two pitot-static (P/S) probe heaters on the right-hand side was lost, and the flightcrew discovered conflicting procedures in the flightcrew operations manual/quick reference handbook (FCOM/QRH). This proposed AD would require revising the existing airplane flight manual (AFM) to incorporate procedures to be applied during P/S probe heater failure conditions. The FAA is proposing this AD to address the unsafe condition on these products.