Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing transport category airplanes. This proposed AD would require repetitive detailed inspections to detect cracking of the aft and forward surfaces of the bulkhead web at nacelle station 180, and repair if necessary. This proposed AD is prompted by reports of cracking of the web bulkhead at nacelle station 180. We are proposing this AD to detect and correct fatigue cracking of the web bulkhead, and consequent loss of the load path of the bulkhead at nacelle station 180, which when combined with the loss of the midspar load path, could result in the in-flight separation of the engine and strut. Such separation may result in secondary damage to the airplane and consequent reduced controllability of the airplane.