Door fittings key to safety probe

U.S. regulators have grounded all Boeing 737 MAX 9s after United Airlines and Alaska Airlines discovered loose bolts on door plugs following an emergency landing by an Alaska jet


BOEING 737 MAX 9

Jan 5: Alaska Airlines flight 1282, carrying 171 passengers and six crew, suffers mid-air blowout

Emergency exits 

Made by Spirit AeroSystems


Door plug: Seals door opening that is not used by most airlines

Window

Size: 0.66m by 1.17m

Weight: 27kg

Door frame: Plug attached to frame with bolts, stop pads, and cable assemblies

Stop pads: 12 locations

Lower hinges: 2 locations

Lower hinge bolts: 2 locations 
nited finds up to 10 Max 9s with bolts, that secure plug to fuselage, in need of tightening

Guide roller tracks: 2 locations 
One on each side near top of plug found fractured on Alaska jet

Cable assemblies: 2 locations


Operates 79 737-9s, with seven on order and 56 on option


Entire fleet composed of 737 aircraft, with 65 737-9s and plans to order 27 more


Sources: Aviation Week, The Air Current, Reuters, Seattle Times
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