MIAMI – An airworthiness directive (AD) issued by the Federal Aviation Administration (FAA) has revealed a production issue on 25 737 MAX 9 aircraft. The left and right wing leading-edge blowout doors of the 25 737 MAX 9s could be without a needed sealant.

The issue was seemingly fixed in early 2019 based on a list of affected line numbers, which were delivered between April 2018 and February 2019 to Copa Airlines (CM), FlyDubai (FZ), Icelandair (FI), United Airlines (UA), and Turkish Airlines (TK).

In a quick summary of the AD, the FAA proposed to adopt a new airworthiness directive (AD) for certain Boeing Company Model 737-9 airplanes. This proposed AD was prompted by a report of missing sealant on the left and right wing leading edge outboard blowout door.

The AD would require doing a fluid seal contact inspection and a detailed inspection for missing sealant on the blowout door and applying sealant if necessary. “The FAA is proposing this AD to address the unsafe condition on these products.” According to the AD, the fix should take around 4 hours of labor to complete.

“The FAA received a report indicating that the application of sealant on the left wing and right wing leading edge outboard blowout door was missed during the airplane manufacturing process on some Model 737-9 airplanes. The missing sealant is intended to act as a fuel barrier. In the event of a substantial fuel leak from the wing box, the missing sealant could result in an unintended drain path allowing fuel to come into contact with the engine. This condition, if not addressed, could lead to a large ground fire.”

Boeing 737 MAX 9. Photo: Boeing.

Another Blow to Boeing and the 737 MAX Line

14 of the 25 MAX 9 jets in question are with UA, which is restarting service on February 12 on limited routes from its Huston George Bush Intercontinental Airport (IAH) and Denver International Airport (DEN) hubs.

On its part, CM has six MAXs and started operations before the new year. FZ has three, FI and TK has one, though it has not have restarted its MAX operations yet.

With the Boeing 737 MAX just coming back into service after almost two years on the ground, this is another blow to an already struggling program.

In 2020 the jet lost around 830 airframe orders but did gain orders from Ryanair (FR), Alaska Airlines (AS), Virgin Australia (VA) equalling around 130 airframes which leaves the backlog at just over 4,000 aircraft.

Featured image: Ocean-Hoevet/Airways