@Concours77 Electra
Remember at least one all fatal crash with early Electra's where the complete engine plus nacelle and mounts vibration that you seem to describe took the wing off. It appeared that the wing was too stiff. Redesign changed the natural frequency.
Do not remember reading in that report about such earlier events. Which is rather amazing. |
Originally Posted by ploughman67
(Post 9811993)
Really? You know that for sure? That's a 25s video, no-one (here) knows whether that went on for 1, 10 or 110 minutes.
It's possible that the video was the immediate aftermath and that once secure the vibration was not as severe. We don't know, we weren't there. How about we credit the crew with the fact that the decision made to return to Perth was made with the full facts at their disposal at that time and was the best option of those they considered. However just to raise a couple of points; 1. The video is 41 secs in two clips - presumably spanning more than 41 secs 2. The gentleman on the left at about 25 sec mark says "about half an hour to go" leading me to suspect that it may well have been shaking for > 1 hour at that time. This is supported by quoted passenger accounts ... eg "After the explosion it started to shake, it started to bounce, but overall the captain did a very good job" and "It was literally like you were sitting on top of a washing machine. The whole thing was going. We could see the engine out the window which was really shaken on the wing.". The latter remark also supported by a brief glimpse in the video. 3. Reported that "marine emergency services north of Perth were put on standby to prepare for a possible water landing" so you would have to presume that some level of emergency had been called. 4. In the thread SWISS LX40 [ZRH-LAX] diversion to Iqaluit, of the 226 posts a fair proportion were firmly in support of that crew landing in the middle of the tundra rather than carrying on to a maintenance base. So which is it? Nearest suitable or nearest convenient. Both arguments can't be correct. |
Originally Posted by msbbarratt
(Post 9811679)
... What does that do to the airframe?! It's getting quite a pounding. Would that knock a few hours off the fatigue life?
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Originally Posted by A0283
(Post 9812016)
Remember at least one all fatal crash with early Electra's where the complete engine plus nacelle and mounts vibration that you seem to describe took the wing off. It appeared that the wing was too stiff. Redesign changed the natural frequency.
Do not remember reading in that report about such earlier events. Which is rather amazing. |
What a few people here aren't able to understand (and what I think JamieMaree is trying to explain) is that this diversion (in this case back to Perth) is nothing to do with ETOPS/EDTO. ETOPS just allows the flight to operate further from an alternate airport than usual. The diversion is usually due to a statement in a checklist which says something to the effect of "Land At The Nearest Suitable Airport" and would take place regardless of the sector being ETOPS or non-ETOPS.
On a twin engine aircraft this statement is usually included in the checklists involving in-flight engine shutdown. If the capt didn't shut down the engine but left it running at idle (maybe because he wanted the GEN and HYD systems available) there's an argument that you don't need to Land At The Nearest Suitable Airport. I hope you guys understand now. I personally wouldn't feel very comfortable flying past YPLM to continue hundreds of NM to YPPH with an engine running but incapable of delivering power above idle but that's a different argument. |
Indeed. ETOPS/EDTO etc is a planning exercise. More often than not, you have other suitable and adequate fields you can utilise. It doesn't require you to land at the nominated ports, you're just using them to comply with the rules.
In an emergency situation, you can do whatever you believe is the safest option. Provided of course you can justify your actions and decision making. Air Asia, CTAF, NPA and limited support? It's a no brainer they went to Perth. Ultimately our job is to land the aircraft in one piece with everyone safe. How you get it there is of course always up to much debate. The job was done and the crew should be commended for doing their best and delivering 350 souls home. Well done guys. |
Originally Posted by msbbarratt
(Post 9811679)
It looks like they had lost a fan blade, and that the unbalanced wind milling engine was causing the vibration. What does that do to the airframe?! It's getting quite a pounding. Would that knock a few hours off the fatigue life?
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If my aircraft was shaking so violently from a windmilling fan with the engine shut down as per severe damage procedures I'd be landing it on the nearest suitable piece of concrete not trucking on
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Too little info to go on at this time. I haven't seen any photos of the engine, nor
confirmation of the extent of a possible fan blade failure. However the manufacturers do conduct full up blade loss tests and verify that the engine will remain on the wing even during windmilling for long diversions. The only problems I have seen in the historical data is that although the engine is shut down by the crew that if the front bearing structure is severely damaged, then as the plane slows down to land the windmilling speed has a tendency to shake the passengers and their seats. No concern for the engine mounting or any airframe loadings which are designed for much worse in turbulence and gusts. The pilots are advised to be prepared for such a crossover speed vs vibration change and if it causes difficulty in reading instruments to simply change airspeed up or down. I presume, no injuries nor broken aircraft critical structures but will await the AAIB reports |
But, ...
Originally Posted by pax2908
(Post 9811744)
From that article - "[Crew] said 'I hope you all say a prayer, I'll be saying a prayer too".
Wow ... is that a standard thing to say to calm people ? So their plan was to appeal God's inerrant decision? |
Originally Posted by lomapaseo
(Post 9812125)
The only problems I have seen in the historical data is that although the engine is shut down by the crew that if the front bearing structure is severely damaged, then as the plane slows down to land the windmilling speed has a tendency to shake the passengers and their seats.
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Originally Posted by lomapaseo
(Post 9812125)
No concern for the engine mounting or any airframe loadings which are designed for much worse in turbulence and gusts.
It's similar to the wisdom of the wear and tear put on cars on the cross channel hovercraft (back in the day). Only a few bumpy trips would be enough to wreck the suspension. So either Airbus have a specification for this, or they don't. If not, they're going to have to pronounce on what remedial action is required. |
Originally Posted by A0283
(Post 9812016)
Remember at least one all fatal crash with early Electra's where the complete engine plus nacelle and mounts vibration that you seem to describe took the wing off. It appeared that the wing was too stiff. Redesign changed the natural frequency.
Do not remember reading in that report about such earlier events. Which is rather amazing. This is what I saw on the day.... I was literally within two feet of the Propellor's arc https://m.youtube.com/watch?v=j6Q5ggtV-y8 By the way, I was aboard well after 1960. They did not fix it, they "mitigated" whirl mode. |
The job was done and the crew should be commended for doing their best and delivering 350 souls home. Well done guys.
Seriously? With a vibration like that, I would be VERY concerned of that engine module eventually letting go and taking half the wing with it. There would be absolutely no doubt in my mind, Learmonth at Vmin. :ugh: |
Your all throwing big words at this flight crew and airline like EDTO, ETOPS and adequate training. Praying works, Isaac Newton was wrong. The ATSB needn't investigate.
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So the Captain asks for Prayers and he also will say a prayer as well!!!!??
Another reason my family and I will never be on an Air Asia flight. Totally unprofessional no matter how good his hand skills are |
The Captain himself feared for the flyability of the aircraft. When you exhort your passengers to pray in order to survive, it's time to land on the nearest piece of asphalt.
Just another inexplicable action by the crews of this airline. |
Turn back to PER would've been appropriate if there was a need for fuel usage to achieve safe landing weight. Alternative would be a dump then land at Learmonth which costs time anyway. If the captain genuinely thought they were in serious trouble then Perth would provide a much better emergency services/rescue option with the airport closer to better equipped medical facilities in the event there was a catastrophe.
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Originally Posted by WingNut60
(Post 9811745)
Looks like turn back occurred about 1:20 into flight; then 1:45'ish for return to Perth
You're at good altitude in a functioning but "abnormal" aircraft. You have a whole collection of checks to do, and then you've got to set-up for landing. It takes quite a while to prepare an airliner for a landing - and more if unfamiliar with, say, Learmouth. The last thing you want is to rush and make silly mistakes. You're about 20 mins from Learmouth, but it will take longer than that for normal (or for a drift-down) descent. You can orbit near Learmouth, doing the checks and prep, slowly descending. Or you can do the checks and preparation while continuing on to a more suitable airfield. Captain's choice but you can see that Learmouth might not be the obvious choice. Same as the Rex that dropped a prop only a few minutes from their planned destination. Somewhat pointless addition because PPrune readers :ugh:
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Originally Posted by Capt Kremin
(Post 9812334)
The Captain himself feared for the flyability of the aircraft. When you exhort your passengers to pray in order to survive, it's time to land on the nearest piece of asphalt.
Just another inexplicable action by the crews of this airline. |
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