United Airlines maintenance appeared to be hanging out the window of the cockpit on a Boeing 737, using a coat hanger to try to make a repair, and that concerned some passengers on flight 1928 from Newark to Austin on Wednesday night.
The 7:30 p.m. departure wound up running two and a half hours late, when the aircraft wound up getting swapped. But the procedure certainly looks suprising to passengers on the ground!
Maintenance crew in a high visibility jacket can be seen in the video leaning out the open cockpit side window and using what looks like a hanger to flick or nudge the small paddle-shaped vane on the side of the aircraft’s nose. Later we see someone get on a service platform by the other cockpit window and coordinate with someone inside.
It looks like they’re addressing an angle-of-attack vane, which measures the angle between an aircraft’s wing and oncoming airflow, providing important data to prevent stalls. And you’d want to be in the cockpit if you were trying to watch indicators while moving the vane. The vane might have been sticking, contaminated, or giving a frozen/bad indication, so moving it was a way to see whether the cockpit reading changed.
That alone wouldn’t let maintenance sign off on a repair of the aircraft this way. The sensor would need to be calibrated.
These sensors are triggering to anyone watching this, because the issues with the 737 MAX stemmed from a faulty angle of attack sensor. The MCAS system was taking data from just one of the sensors at a time, single bad reading could trigger a repeated nose-down stabilizer trim.
This was a bad design, and the system now compares both angle of attack sensors and if the readers betweeen them are off by 5.5 degrees or more the system will not activate (and wil give pilots a disagree alert). An angle of attack sensor error is no longer as serious as it was eight years ago!
The equipment swap actually shows that the system working. The plane had an issue, and United didn’t dispatch it. The optics here are uncomfortable for a passenger not knowing what’s happening, though. But nobody actually cleared the aircraft based just on poking the vane with a hanger.
Gary Leff writes, “The optics here are uncomfortable for a passenger not knowing what’s happening.” Imagine a United Airlines Boeing 737 mechanic hanging out the cockpit window like a human flag in a windy storm, using a coat hanger to fix things. To spare the passengers from mental images they didn’t ask for, it’s best to schedule this act of aerial acrobatics under the cover of night or safely tucked away in a hangar—preferably with a ‘Do Not Disturb’ sign that says, “We’re just decorating!” Because really, fixing a passenger jet should be less like a magician’s reveal and more like making sausage: better if you don’t know the messy details!
Just like with the speed tape. Doesn’t look great, but if it gets the job done, can’t complain… bah!
That is not a coat hanger, it is a vane adjuster. The shape of it is just a coincidence. (sarcasm)
I bet this was just a quick/east test to determine if the sensor needed to be replaced or recalibrated so the mechanic could determine which repair path to go down as quickly as possible.
If I had a choice of hours of delay vs. fixing something with a coat hanger—I am voting for the coat hanger. Experienced mechanics and repair folks in general have many tips, tricks, and shortcuts that get the job done safely and correctly.
Leslie, I don’t think those are your only two options.
angle of attack sensor can cause the stall warning system to engage the stick shaker if it is in the wrong position.
This is a common problem if the wind moves it to a high angle of attack. The vane may be hot after flight. (vane is heated to prevent ice from causing it to stick).
He should have used a selfie stick.
Aircraft mechanics what you didn’t know:
Most of us are autistic which when mixed with aviation and some coffee leads to some truly outside the box thinking.
There is always a set of dudes that are trusted to do the shady shit because they are the ones who are best to do it “safely”.
Pretty sure there’s a Steven Wright joke about this, and is how he lost his job at Logan airport.
Having worked on the 737 for years, many tests require the AOAs to be positioned in relatively level positions (Stall warning, auto-slat, etc.). You would typically just move them by hand if needed. They are heated, but not on the ground unless you turn the heaters on manually. From the video, you can see the vane on the Captain’s side is positioned pointing up. Testing can’t be accomplished until the vanes are repositioned as the AMTs did. Using the coat hangers allowed them to do it without leaving the flight deck. This is the lazy method, but it does not cause any harm to the sensor.
@ W.B –
Stick shaker activation on the ground is only possible during certain test modes that require overriding the air/ground signal to put the aircraft in “air mode.” The same is true for the auto-activation of the heaters. So this could be the case, but only if they put the aircraft in air mode and did not pull the circuit breakers for the heaters, as the maintenance manual instructs you to do.