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TransAsia in the water?

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TransAsia in the water?

Old 6th Feb 2015, 12:30
  #281 (permalink)  
 
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Looks to me like...

While this is a rumour network and we are all entitled to an opinion there is no such manoeuvre as stretching the glide...

You either maintain controlled flight and have some influence over where you crash or you don't.

Someone has to fly the aircraft.
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Old 6th Feb 2015, 12:40
  #282 (permalink)  
 
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In a situation where you can see houses and a motorway coming up to you fast, I would defy anyone not to try to 'stretch' the glide by pulling up at the last minute.
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Old 6th Feb 2015, 12:40
  #283 (permalink)  
 
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You either maintain controlled flight and have some influence over where you crash or you don't.
And that is the point.

But regardless of what the engine instruments are saying, the control inputs will give a significant clue as to what is happening. Dead leg, dead engine?

From the radar track it looks like they never got on top of controlling the flight path neither horizontally nor vertically.

I'd go so far as to add a further '-ate'.
Aviate
Navigate
INVESTIGATE
Communicate.
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Old 6th Feb 2015, 12:59
  #284 (permalink)  
 
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UK media reporting just now double engine failure from investigators
Oh dear I had a feeling it might be that. It reminds me of the SAA Airlink crash a few years ago when the capt (probably relying on gut instinct and didn't verify visually) pulled the wrong condition lever.
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Old 6th Feb 2015, 13:02
  #285 (permalink)  
 
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Something doesn't add up on the FDR trace.

I've fine-pencilled / ruler'ed it. The first event appears to be the uptrim on #1, at 2:52:34. Increase in FF, ITT and Obj Tq. Once the Obj Tq on #1 reaches 100%, at 2:52:37 there seems to be a simultaneous Master Warning #2 Flameout, start of rise in Beta 2 (feathering), and a simultaneous drop in all #2 parameters, except the FF, ITT, NL and NH, which drop then stabilise (presumably at idle?) - so no ACTUAL 'flameout'.

The #2 looks like it didn't autofeather until 3 seconds AFTER the uptrim on #1 - and there doesn't seem to be anything in the trace that precipitates the #2 autofeather?

Shortly after that, #1 throttle is retarded about 10 deg. Not unusual I would suggest if they were having directional control problems. However, it is then progressively retarded (and at one point, the #2 throttle firewalled?) until the Fuel Shut Off is activated at approx. 53:15:22. Unlike the #2, the flame DOES go out in #1.

#2 turbine is running throughout.

In the last few seconds, it looks like #2 starts to unfeather (increase in Beta) - this seems to coincide with the #2 throttle being pulled back. #1 stays feathered throughout, although appears to relight as soon as the Fuel Shut Off is cancelled.

Seems like an odd sequence of events to me?
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Old 6th Feb 2015, 13:05
  #286 (permalink)  
 
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Originally Posted by phiggsbroadband
Am I right in saying that they did restart Eng1, as ITT1 had risen ten seconds prior to the end of the recording?
Looking at the ITT and the NH values for the number 1 engine, it does appear number 1 was relighted. But by that time they were probably too late.
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Old 6th Feb 2015, 13:28
  #287 (permalink)  
 
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The #2 looks like it didn't autofeather until 3 seconds AFTER the uptrim on #1 - and there doesn't seem to be anything in the trace that precipitates the #2 autofeather?
Note that some parameters are only recorded every few seconds, sometimes as low as every 4 seconds, so if something appears to happen 3 seconds after another event, it may actually have happened almost 1 second earlier, but the change wasn't recorded until later.

A hint to the frequency is given by the slope of the linear segments combining the data points. I have long said that doing this kind of linear interpolation is wrong and misleading. These graphs should only show the actual data points and not try to imply data where there is none.
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Old 6th Feb 2015, 13:32
  #288 (permalink)  
 
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The autofeather won't occur for a period of a couple seconds after the uptrim normally.
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Old 6th Feb 2015, 13:45
  #289 (permalink)  
 
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The view from outside of aviation looks at the cause as:

"if not for" the initial engine failure .......

while the insiders view is:

"in spite of " a single engine loss of power .......

My initial questions are:

Why would the crew even think of taking action on any engine at a critical flight regime? I thought the concept was to take your time, aviate, navigate, communicate. Somewhere in this I would expect some aircraft configuration changes, but not turning off an engine until late in the process.
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Old 6th Feb 2015, 13:57
  #290 (permalink)  
 
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You would hope that were the case. Perhaps the line check (if it was) in progress had affected the crew's actions in some way.

For me it's fairly clear what happened. In the last seconds perhaps the lca realized what had happened and called for the left engine to be relighted. Who knows really.
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Old 6th Feb 2015, 14:00
  #291 (permalink)  
 
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Drunk Pilot makes a good point. Did the number one engine/prop come out of feather momentarily increasing drag just before increasing thrust and dip the left wing?




IF we didn't have the video, the solution might be more forthcoming. But the number two engine is clearly visible and its prop is spinning rapidly. The pitch of the prop blade is not visible however.

Having a cockpit video camera would show us what the pilots saw on their engine gauges, and how they responded to it.
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Old 6th Feb 2015, 14:02
  #292 (permalink)  
 
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Originally Posted by Massey1Bravo
Oh dear I had a feeling it might be that. It reminds me of the SAA Airlink crash a few years ago when the capt (probably relying on gut instinct and didn't verify visually) pulled the wrong condition lever.
I remember being involved tangentially in a similar double engine fail after take off very very similar except the aircraft crashed straight ahead into a field 2 miles or so along the extended center line. That one was caused by a refuel with incorrect fuel.
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Old 6th Feb 2015, 14:04
  #293 (permalink)  
 
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possible explanation

I found something that might explain the wrong engine selection for shutdown:
"
A prop that has autofeathered is being turned with an enormous amount of power. The resultant torque has an incredible effect on the rest of the airplane, trying to turn the airplane about the prop (i.e. roll moment) - much the same as a helicopter with a failed tail rotor.
"

"Additionally, if the uncommanded autofeather is not correctly identified, there is a real tendency, demonstrated time and again in simulators, for shutting down the wrong engine. Hence the importance of verifying engine malfunctions from as many indications as possible prior to taking any action towards shutting down."

So no2 error trigger the autofeather of that engine - this banks the plane into the other engine making them think is was that other one who failed .
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Old 6th Feb 2015, 14:08
  #294 (permalink)  
 
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Something doesn't add up on the FDR trace.

I've fine-pencilled / ruler'ed it. The first event appears to be the uptrim on #1, at 2:52:34. Increase in FF, ITT and Obj Tq. Once the Obj Tq on #1 reaches 100%, at 2:52:37 there seems to be a simultaneous Master Warning #2 Flameout, start of rise in Beta 2 (feathering), and a simultaneous drop in all #2 parameters, except the FF, ITT, NL and NH, which drop then stabilise (presumably at idle?) - so no ACTUAL 'flameout'.

The #2 looks like it didn't autofeather until 3 seconds AFTER the uptrim on #1 - and there doesn't seem to be anything in the trace that precipitates the #2 autofeather?

Shortly after that, #1 throttle is retarded about 10 deg. Not unusual I would suggest if they were having directional control problems. However, it is then progressively retarded (and at one point, the #2 throttle firewalled?) until the Fuel Shut Off is activated at approx. 53:15:22. Unlike the #2, the flame DOES go out in #1.

#2 turbine is running throughout.

In the last few seconds, it looks like #2 starts to unfeather (increase in Beta) - this seems to coincide with the #2 throttle being pulled back. #1 stays feathered throughout, although appears to relight as soon as the Fuel Shut Off is cancelled.

Seems like an odd sequence of events to me?
I think that ENG #2 lost power and rolled back to a state of around idle or so, this triggers the ATPCS sequence which is activated by ENG #2 producing less than 18% TQ, ATPCS immediately uptrims ENG #1 to RTO, closes bleed #1, and after a delay of 2.15 seconds feathers ENG #2. This is all just as it is supposed to be.

As I read the DFDR data engine #2 suffered some sort of malfunction, but not necessarily a complete flame out. In any case the warning will be ENG FLAME OUT.

It seems that the crew proceeded to retard PL1, and move CL1 to FEATHER and then FSO.

The increase of Beta #2 at the end could be produced by moving the Power Management selector away from take off, which cancels the auto feather signal, and as CL #2 was never moved to FSO Prop # 2 will start to un-feather. A highly undesired status.

Moving the Power Management selector away from take off is a normal thing to do if attempting an airborne relight. But only if all preceding procedures have been completed correctly.

Unfortunately it seem the crew were thoroughly confused, and shut down the operating engine.
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Old 6th Feb 2015, 14:13
  #295 (permalink)  
 
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Lomapaseo,
in case of an engine malfunction on a turboprop, it is imperative that the engine is brought into a state that is covered by the performance calculations, and rather quickly. This positively requires the propeller to be feathered. I have not flown the ATR, but on the DH8-300, only a tiny ROC was achievable with a dead, windmilling propeller and required some rigorous guiding of the aircraft.

So there are long lists of memory items for engine malfunctions that are performed as soon as the gear is up and before any call to ATC is placed. On the DH8, they consist of setting maximum permissible power on the good engine, then checking the dead propellers feather state and absence of fire indication. If the engine is feathered and not indicating a fire, the next manipulations to it will take place after a call to ATC, acceleration, cleanup and unlike the memory items with the QRH in hand. If however either of those requirements are not met, the memory items continue with retarding the affected power lever, setting the condition lever to "FUEL OFF" (both handled by PNF but confirmed by PF), activating the alternate feather pump (just in case), and in case of fire indication as well switching off the auxiliary fuel pump, pulling the affected T-handle (again, verified correct by the PF) and discharging at least one bottle. All this is done by heart and without checklist reference, while the PF flies the aircraft by hand (using the A/P below 1000ft after T/O is not allowed).

Who says that flying a turboprop is easy and low on workload obviously has never tried it...
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Old 6th Feb 2015, 14:25
  #296 (permalink)  
 
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All those steps (minus feathering) occur in jets too. Planes like the ATR and the EMB-120 I flew all have autofeather. 99.99% of the time that system will work as advertised. There is the additional step of confirming it has worked. If it hasn't, that involves more for sure.

It looks to me at least the ATPCS worked as it should have, but the crew have applied a procedure to the wrong engine. Any way you look at it, it's a major cockup. Rushing never produces a positive outcome. Ever. I'd almost rather be in a forced landing scenario with an unfeathered propeller than shutting of the good engine. (Perhaps not on an EMB120 with 1800hp/side.) Beastly to control even with a feathered prop. Not sure about the ATR..

All that said, there may be a lot more to this one. Maybe not, however.

Last edited by FIRESYSOK; 6th Feb 2015 at 14:43. Reason: clarifications, you know..
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Old 6th Feb 2015, 14:27
  #297 (permalink)  
 
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Relight impossible with zero fuel flow!

Note - read with caution: 1st post from a non airman.

First QRH check item in an ENG RESTART IN FLIGHT is:
FUEL SUPPLY .............. CHECK.
(OK, admittedly my source used is the ATR 72-500's QRH)

According to the investigators (see post #239), at time 53:19 the crew discussed that engine #1 was feathered and noted that it's fuel supply was cutoff. That's because they had manually flicked the fuel cutoff CL on the O/H panel as per standard shutdown sequence, right?
Investigators said the crew then "decided to attempt restart of #1."

Problem was, they left the fuel cutoff CL in the OFF position for the next 56 seconds (from 53:23 until 54:19 on the FDR trace), during which the investigators noted several attempts at relight were tried unsuccessfully.

Others here have noted evidence of a successful relight of engine #1 during the A/C's last airborne 15 seconds or so, that is, AFTER the fuel supply was manually turned back ON.

If only ...
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Old 6th Feb 2015, 15:06
  #298 (permalink)  
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I've tried to keep up, but I don't think the question I posed was answered. Are the 600's fuel booster pumps still switched on manually WITH NO WARNING IN T/O CONFIG?

Sorry to raise my voice, but I always thought that utterly barmy. Failure to turn these on could result in anything from not a hint of a problem to engine being throttled with obvious results. What is significant is that the effects were not the same on both sides leaving a set of mixed symptoms

Our company had a couple of emergencies declared before that Doh! realization moment.
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Old 6th Feb 2015, 15:07
  #299 (permalink)  
 
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Was this a Line Indoctrination or Line Check flight? Do we know for sure who was sitting in which seat?

http://avherald.com/h?article=48145bb3&opt=0
On Feb 5th 2015 the airline reported that the two pilots at the controls had 4,914 hours and 6,922 hours total flying experience, an instructor with 16,121 hours total occupied the observer's seat.

the pilot in the left hand seat had 4,914 hours of total experience, in the right hand seat 6,922 hours total experience and the instructor on the observer's seat 16,121 hours total experience.
TransAsia Airways Flight 235 - Wikipedia, the free encyclopedia
Captain Liao Chien-tsung, age 42, a Taiwan citizen, had a total of 4,914 flying hours;
Captain Liu Tzu-chung, a dual Taiwan-Hong Kong citizen, had a total of 6,922 flying hours;
First officer Hung Ping-chung, a Taiwan citizen, had a total of 16,121 flying hours.

Last edited by Lost in Saigon; 6th Feb 2015 at 15:20.
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Old 6th Feb 2015, 15:09
  #300 (permalink)  
 
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Absolutely, flying a turbo prop is just as difficult as a jet, when it all starts to go wrong.

Apologies if this has been discussed, but what is this auto rudder system on the ATR?

Dead leg = Dead engine,

...is a very useful way of identifying a failed engine in a multi engined aircraft. If all the rudder is being put in for you, you will not have this confirmation?
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