Summary
The FAA proposes to adopt a new airworthiness directive (AD) for all 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. This proposed AD was prompted by reports that high temperature composite trim air diffuser ducts (TADD) showed composite degradation and signs of hot air leakage. This proposed AD would require a one-time low frequency eddy current (LFEC) inspection of certain center tank upper skin panels on the right and left side for any structural damage due to heat exposure, and repair if necessary. The FAA is proposing this AD to address the unsafe condition on these products.