Summary
The FAA proposes to supersede Airworthiness Directive (AD) 2007-07-03, which applies to certain The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes. AD 2007-07-03 requires repetitive tests to detect hot air leaking from the trim air diffuser ducts or sidewall riser duct assemblies (collectively referred to as TADDs), related investigative actions, and corrective actions if necessary. AD 2007-07-03 also provides an optional terminating action for the repetitive tests. Since the FAA issued AD 2007-07-03, operators reported high temperature composite material TADDs installed as specified in AD 2007-07-03 have also failed. This proposed AD would require repetitive inspections of all TADD material for damage and applicable on-condition actions. The FAA is proposing this AD to address the unsafe condition on these products.