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UAL 1175 fan blade failure in 2018

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UAL 1175 fan blade failure in 2018

Old 4th Mar 2021, 08:10
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UAL 1175 fan blade failure in 2018

I have just come across this interview with the captain on the UAL 1175 incident into Honolulu in which he describes some of the difficulties they experienced. The blade failure was much like the recent one at Denver, but I have not heard of any significant handling problems on UAL 328, does anyone have any information?

This report raises several important issues:-

1. The need to retain good handling skills for when something really difficult happens.
2. The difficulty of maintaining altitude with both an engine out AND considerable excess drag.
3. The validity of the ETOPS assumptions had this incident occurred near the mid point enroute.
4. The value of having an extra crew member in the cockpit (remember QF 32).

Food for thought.

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Old 4th Mar 2021, 10:22
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easa etops rules:
If the engine failure occurs at the worst point enroute, this could mean (worst case) that you end up diverting and arriving with 15 minutes holding fuel at your etops enroute field. This automatically results in a low fuel energency of course.
does this differ from Faa rules?
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Old 4th Mar 2021, 10:53
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fox niner, Where would you find a diversion field between San Francisco and Honolulu? And do the ETOPS assumptions allow for the extra drag this crew experienced? I doubt, had this failure occurred at the worst point, they could have reached Honolulu with min fuel, or have been able to return to the US mainland - did you listen to the last part of the video?
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Old 4th Mar 2021, 12:07
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The captain stated he couldn't maintain altitude, either. You don't have to back this up to the FTP, just back it up perhaps 200 miles further east of PHNL.
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Old 4th Mar 2021, 13:37
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but I have not heard of any significant handling problems on UAL 328
This happened at FL360, M0.84, a whole different game. I was shocked to hear how violent the deceleration was and the vibration levels to such extent they couldnt even use the ECL. It became not exactly clear from the interview whether at low altitude they were able to maintain altitude and speed, they assumed they were not but I understood they didnt try to not end up too much outside the established "flyable" envelope.

Interesting fact about why the TAC failed based on my understanding of TAC. As far as I recall, the TAC will still require a valid N1 signal to perform its own estimates. They hard severed cables and invalid N1 and therefore TAC was not able to determine the estimated thrust of the engine and faulted.
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Old 4th Mar 2021, 14:24
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Outstanding piece of aviating. Worrying that much further out would have ended in the water, night time at an ETOPS point? Perhaps the engine pods need a jettison button.
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Old 4th Mar 2021, 15:20
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Worrying indeed ...
It is a given that one will need to come down to more "consolidated" air. Assymetries at high altitude ... and it is very easy to lose control of the ship.
But not being able to maintain altitude on a twin, with the other engine at MCT, being it at 15000', or 10000', or 5000', is indeed very worrying.
It seems that Certification needs a very good review of requisites or specs, and this is for both sides of the Atlantic.
The very first accident of a 767 was a deployment of a reverser inflight at 20 something thousand feet. Flip it upside down, went into a dive, into overspeed, and inflight break-up.
It seems that Boeing had tested the aircraft with a reverser deployment inflight, but it was at a much lower altitude, and it was controlable. At high altitude it is impossible to control.
Got tired of doing 8 or 10 hour sectors, so decided to move to something smaller, the european turboprop of the Airbus group. Max certified altitude is 25000' and it can take 68 pax.
Sometime ago did a flight with 7 pax onboard. It was a bit longer sector, so we decided to go to FL240. From FL220 upward it climbed at 300'/min. Thought to myself ... WTF, with 7 pax onboard it only does this ? Spoke with an examiner that did some testing on the aircraft. He mentioned that on an empty aircraft, with an one engine at idle, the aircraft barely climbs.
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Old 6th Mar 2021, 11:20
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The TAC will fail as it had no valid N1 from the damaged engine, a simple TAC reset will restore it. (which is what the ECL / QRH will direct you to do with the EICAS message THR ASYM COMP.
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Old 6th Mar 2021, 14:56
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Originally Posted by Bergerie1 View Post
but I have not heard of any significant handling problems on UAL 328,
It seems the origin of the problem was the same, a fan blade failure. However the resulting damage might have been very different.
From the videos of both events it seems that in both cases the Fan was rotating. The difference might be on how freely they were rotating in each case ?
I would say that in the Denver case the Fan was more free to rotate, resulting in less drag, and therefore a flyable aircraft.
In the Honolulu event, although it seems it was also rotating, with the associated vibration, it might be the case that it was a lot more seized, causing a lot more drag and an aircraft more difficult to fly/control.
The area of one of this fans is huge, and if one of this things seizes completly, then the chances are that one will be in for an interesting day.

It became not exactly clear from the interview whether at low altitude they were able to maintain altitude and speed, they assumed they were not but I understood they didnt try to
Agree with that. Unable to tell, but remember the Captain saying towards the end of the interview that there would be no chance of going around. They were commited to land.

Last edited by zerograv; 6th Mar 2021 at 16:11. Reason: grammar
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