Following an airworthiness directive (AD) issued by the Federal Aviation Authority (FAA) on October 2 and effective from October 3 demanding carriers inspect 737 NG aircraft which have accumulated 30,000 or more flight cycles within a seven-day period, 13 of the jets have now been grounded. These include two operated by Southwest Airlines and 11 by Brazil's Gol Linhas Aereas.
The directive also ordered carriers to inspect all 737 NGs within the next 1,000 flight cycles if they have already accumulated between 22,600 and 29,999 cycles, with all inspections subsequently to be reported to the FAA. In all, 1,911 of a total 1,930 of the current fleet of 737 NGs will require inspection at some point.
The directive was issued as a result of cracking found in the pickle fork which connects the wing to the fuselage of the aircraft. The inspections involve looking for “cracking of the left- and right-hand side outboard chords of frame fittings and failsafe straps.” The directive was immediately issued by the FAA after being notified by Boeing that while undergoing passenger-to-freighter conversion in China, this specific fault had been identified in a number of aircraft which had completed between 35,600 and 73,300 flight cycles. It is understood that light cracking might be found in an aircraft which has completed approximately 90,000 flight cycles and reached the end of its lifespan, but cracking after so few flight cycles was unusual.
