[durt]

2018 built Alaska Airlines Boeing 737-900 aircraft (N293AK) headed for San Diego returned to Seattle-Tacoma International Airport (SEA) shortly after takeoff , as it observed vibration due to unlatched Engine 1 fan cowlings. Fan cowlings were lost on landing.

[ride]

Aircrew should have caught it on their pre-flight walk around.

Id like to know whether the aircraft had just came out of scheduled maintenance, phase dock, or ?

[Ramplead]

Never latched the cowling?

[William May]

Originally Posted by Ramplead ↗

Never latched the cowling?

The latches are on the very bottom center of the cowling. If you look at one of those 737-300s, they actually had to flatten the inlet nacelle at the bottom, so it would clear the ground. They aren't round at all. The latches are painted red, so they stand out when they are unlatched, like little 6" long sticks, but you wouldn't see them on a walkaround, unless you kneeled down or slid on the ground under the nacelle. What they may have done is snapped them over the catches, but not pulled them up tight to the latched position, so if that was the case, they would be VERY hard to detect. In that case you only see the little red lever latch sticking out, and it's only an inch or so long. Mechanics fucked up. Ground crew never touch those, and the flight crew would never have touched them, either. Probably from the previous night's "A" check.

[William May]

Those cowls were a pain in the ass all the time. If you DO have them opened for maintenance, and someone turns on the hydraulic pumps and puts the flaps down, (Which you would do so you can grease all the flap tracks) the leading edge slats move right down into the cowl doors and crush the shit out of them. That was a common occurrence when people were in a hurry. They kept spare cowls and leading edge slats in stock because of that. Eventually they made it the crew chief who was running the "A" checks responsibility to install the slat lockouts on a valve under the belly, BEFORE ANYONE WAS ALLOWED TO TOUCH THE AIRCRAFT. That became absolutely the FIRST thing you did when you walked up to the airplane. There were actually lockouts for every system, and they put most of them high up in a large panel in the tail, on the assumption that that was the least likely place they could be damaged in flight.
(Until that DC-10 in Sioux City had the tail-engine fan disc fail, and on the way out of the airplane, it went right through that lockout panel and destroyed every single hydraulic system on the aircraft, instantly. (That was the airplane that the pilot used the throttles to keep control of the aircraft, and crash landed it, but most people survived.)

With that panel, you could operate just a single landing gear or brake or whatever, without having to have every line in the hydraulic system connected. Or if one hydraulic system was down because the filters were pulled out, or hoses were being time-changed, or for any other reason.

[durt]

Fucking fan cowls, they've only been left unlatched about a million times!!

[wildaxboxer]

Wonder if they have got the smell of shit out the plane yet