Allegiant MD-83 Elevator Failure

N64

Reported on AVHEARLD, an Allegiant MD83 flying out of Las Vegas while on it's takeoff roll pitched up in the air by itself. Pilots noticed this and were able to abort the takeoff without further incident. Reminds me very much of the Alaska air 261 crash over 15 yeas ago.

Lucky that events played out as they did. Would have most likely resulted in a crash if they got airborne imo. One question I have is that wouldn't the crew notice the jam in the preflight control checks?

martinsvi

I'd say that was as close as it gets, wasn't one of the findings from Alaska air crash that the elevator bolt has no redundancy and wasn't there a recommendation to redesign this thing?

Irish Steve

My read of the article is that the link to the left elevator power control unit failed, which caused it to jam in the full nose up position, but there was no restriction on the movement of the control yoke, so a "full and free" movement check would not have shown up any issues.

I've not been on the flight deck of the MD83, so I don't know if there is a control position indication back to the flight deck, and even then, the nature of this fault might not have shown up the fault.

The only time this might, repeat might have been seen was during an external walk round, if the elevators were not both in the same position, but I can't remember now if the 83 goes into nose up elevator when the power is off, some aircraft do, which would have masked this issue.

_dof_

Irish Steve wrote: »

I can't remember now if the 83 goes into nose up elevator when the power is off, some aircraft do, which would have masked this issue.

I thought that was the case, and this picture seems to confirm it.
http://jetphotos.net/viewphoto.php?id=163315&nseq=14

Irish Steve

In which case, this would not have been visible on walkround, and not felt as part of pre flight checks, so they had a very close call with this failure.

N64

martinsvi wrote: »

I'd say that was as close as it gets, wasn't one of the findings from Alaska air crash that the elevator bolt has no redundancy and wasn't there a recommendation to redesign this thing?

Even after the Alaska air crash, the vertical stabilizer still doesn't have any sort of redundancy built in. The jackscrew system is meant to be very safe PROVIDED that maintenance and inspection are carried out properly (e.g. making sure the threads aren't worn and are greasing it properly)

This seems to be completely unrelated though.

triggermortis

_dof_ wrote: »

I thought that was the case, and this picture seems to confirm it.
http://jetphotos.net/viewphoto.php?id=163315&nseq=14

I just read the AV Herald link there and the MD83 elevator should float free. The controls in the cockpit control the trim tabs, which then aerodynamically move the elevators in flight (same as the 146/RJ), so on the ground, with power on or off, the elevators could be in any position - one up, one down for example. There is no control position indicator in the cockpit for the elevator either

triggermortis

N64 wrote: »

Even after the Alaska air crash, the vertical stabilizer still doesn't have any sort of redundancy built in. The jackscrew system is meant to be very safe PROVIDED that maintenance and inspection are carried out properly (e.g. making sure the threads aren't worn and are greasing it properly)

This seems to be completely unrelated though.

It may not be completely unrelated. The screw jack needs to be lubricated and checked for anything untoward - worn parts, split pins/wire locking in place etc, but it is good maintenance practice to have a look around the whole area for anomalies. I don't know the MD83 to I don't know how close the screw jack is to the part that came detatched and jammed.

Luckily in this case, the pilots did a great job in recognizing something wasn't right and aborting the take off