The Federal Aviation Administration (FAA) issued a new airworthiness directive (AD) concerning the Boeing 737 NG and MAX family aircraft, after reports of cracks on the stop fitting assembly of the forward entry door.
After investigating multiple reports of “cracked or completely severed lugs in the upper aft corner stop fitting assembly of the forward entry door”, the FAA identified that the “undersized wall thickness of the lug made it susceptible to fatigue cracking.” This could result in the forward entry door of the affected aircraft being unable to sustain the limit load, thus risking a rapid decompression of the cabin. The aircraft and operator that reported the issue were not specified in the AD.
As a corrective measure, the FAA asked operators to identify the stop fitting assembly installed on their aircraft and, if the faulty parts are found, to replace them “with a newly designed stop fitting assembly that has improved wall thickness and strength.”
The new AD, effective March 29, 2021, concerns both the Boeing 737 NG and MAX families and affects 1,075 airplanes registered in the United States. Operators have to comply before 10,000 total flight cycles on the forward entry door, or within 5,000 flight cycles after January 24, 2020, whichever occurs later.