United Airlines maintenance appeared to be hanging out the window of the cockpit on a Boeing 737, using a coat hangar 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 hangar.
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