Airworthiness Directives; The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP Series Airplanes

Resumo

The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain Model 747-100, 747-100B, 747- 100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes. The existing AD requires repetitive inspections and torque checks of the hanger fittings and strut forward bulkhead of the forward engine mount and adjacent support structure, and visual inspections of the internal angle and external bulkhead chord and detailed inspection of internal angles, and corrective actions if necessary. The existing AD also provides for an optional inspection. This proposed AD would also require additional inspections of airplanes that have hi-lok bolts and collars at all of the Group B fastener locations, except fastener 13, and related investigative and corrective actions. This proposed AD would require repetitive inspections of the internal angle and corrective actions, if necessary. This proposed AD also would require, for certain airplanes, replacing the fasteners, which terminates certain repetitive inspections. This proposed AD results from the reports of undertorqued or loose fasteners, a cracked bulkhead chord, and a fractured back-up angle. W