TransAsia in the water?

[skyhighfallguy]

royale

can you tell me how the right engine/prop is placed into "HOTEL MODE" for ground use as a pseudo apu?

[pattern_is_full]

Finally, why are the FDR traces all engine related, except the Main Gear, VHF1 (what is this?) and height readings? Where is the airspeed, vertical speed, control positions, etc?

The FDR tracings cover multiple pages (unless graphed at too small a scale to be readable/useful). The parameters you mention are on a different page - not yet released.

[Royale]

can you tell me how the right engine/prop is placed into "HOTEL MODE" for ground use as a pseudo apu?

It is done via a guarded swith on the overhead panel, ac needs to be on ground,gust lock engaged and prop #2 feathered.

If that had been a part of this accident there would also have been a prop brake unlock warning.

The prop bake is not capable of stopping an unfeathered propeller, it will destroy the propbrake itself by heat, and possibly cause a eng fire warning too.

[skyhighfallguy]

thank you Royale. The Hotel mode concept is a strange one to this pilot. Could any aspect of hotel mode be figuring in the right engine / prop combination not producing thrust?

[Royale]

I really doubt that the propbrake played any part in this.

I know of an incident where for some strange reason the crew attempted a takeoff with the propbrake engaged, it resulted in the propbrake mechanism disintegrating due to excessive heat, and a fire warning due to that heat. But no loss of thrust.

[Lost in Saigon]

Originally Posted by Royale

On the ATR you even have an intermediate position before fuel shut off, called feather, and you really don't want to go past that point unless you are 100% certain. I doesn't take that long to unfeather the propeller again.

Is it Standard Operating procedure to pause at the FTR position or is it just an airmanship thing?

[lomapaseo]

When trying to interpret the DFDR traces give a thought that the sampling rate of its data trace could be much coarser than the detection rate of the computer systems that automatically control its functions.

the way to get beyond this is to trial model some engine performance graphs and then see which ones best match the actual DFDR traces.

[Royale]

Is it Standard Operating procedure to pause at the FTR position or is it just an airmanship thing?

Its procedure in a sort of roundabout way. All irreversible actions have to be confirmed by both pilots, moving from FTR to FUEL SO is irreversible in the short term.

The procedure itself state:
CL affected side.............................................. FTR THEN FUEL SO.

[skyhighfallguy]

royale

I notice the 100% ovrd position and below it auto

would auto be used for arming auto feather on takeoff?
if you autofeather, do you go to 100% ovrd to disengage?

or you can just brief all of us on the different positions.

[strangestranger]

IF the prop was autofeathered as part of the ATPCS sequence, the only way to unfeather is by selecting power management selector to MCT. Any ATR pilot would know this.

[ChicoG]

Security Cam from nearby building

https://www.youtube.com/watch?v=cXTGzO-mCJo

[Lost in Saigon]

Originally Posted by strangestranger

IF the prop was autofeathered as part of the ATPCS sequence, the only way to unfeather is by selecting power management selector to MCT. Any ATR pilot would know this.

[Trackdiamond]

The DFDR analysis posted by HDRW queried why PL1 was retarded some 10 degrees..this was likely to countermand the uptrim on Eng 1 which the crew reckoned it to be unnecessary due to figuring that Eng 2 flameout was probably a false alarm.After that particular action am not sure what kind of comunication was taking place but it vertainly was confusing and the CVR is the only thing that can disclose the truth.I suspect very much it was either an ATPCS, EEC, or Propeller PVM (prop valve module) issue.The fact that the power quadrant is a constant postion lever(gated) and power is regulated automaticvally could be some weird electronic issues at play.Also the PMS is split(two rotary knobs as one..required for certificationp.perhaps there was a disconnect between them that might have caused weird Power Mismanagement?This would have happened at acceleration altitude..anywhere from 400ft to 1000ft but on average 800ft as per company policy when switching it from TO to CLB as part of the climb sequence flow by NFP.

On ATR 500 series there was no QRh procedure for ATPCS failure! If on takeoff..increae PL manually to the wall.If in flight..it was unwritten..and one would switch it off..but no CCAS warning specific to ATPCS.If it wasn't working at dispatch it was MEL GO with a weight penalt of 3600kg..because of performance degradation due to its unavailability.

QRH procedure for Abnorma Eng Parameters in flight:
If intermittent fluctuations or unrealistic steady indication
ATPCS........OFF
*when adequate flight situation
PL affected side FI
EEC affected side...OFF
*(if successful)
One EEC fault procedure....Apply
*(if unsuccessful)
Or-if TQ=0% and NP<77%
PL affected side.....FI
CL affected side.....FSO
Single Eng operation procedure...Apply
*if "---" indication on Torque digital counter...Avoid sudden PL movements.

Hotel mode only a ground ops function.I have had a prop brake unlock but on the grounds..and had to shut down the engine and have maintenance check it as is the SOP.
Prop brake coming on in flight..QRH says continue normal ops...just monitor eng 2 parameters (prop brake on Eng 2 only).After landing...CL2...FSO.

By the way ...on ATR...the PF(handling pilot) is the one whose hands are on the PLs and PM(non handling and monitoring pilot) is the one who confirms and PF moves it to idle.On the other hand the PM has his hands on the CL and PF confirms and the PM moves the CL to FTR and FSO.It is the ATR SOP...PF handles the flying controls and power controls and the PM handles the critical switches wth PF confirmation.The CL os an engine start and prop feathering/unfeathering and rpm control switch...on jets it equstes to engine stat levers..which the PM handles...at PF conformation.

[Jet Jockey A4]

@ Trackdiamond...

Our S.O.P.s and the manufacturer of the aircrafts we fly (not ATRs) the PF only flies the aircraft and guards the good thrust lever and shut off switch and upon his confirmation/command the PNF brings back the failed engine's thrust lever, turns off the engine shut off switch, generator etc.

[Trackdiamond]

jetjockey

I won't argue with that JJ.am just saying that was ATR SOP we used.I found it awkward at first but like any SOP..you adapt and make it your homeplace...regardless of what else you have flown before.

[Lonewolf_50]

Originally Posted by Lost in Saigon

I would be very surprised to find out there is some kind of and "anomaly" which contributed to them shutting down the wrong engine.

My guess had to do with the nature of the malfunction and the display of symptoms, but you may be right that it was something well within the norm of the systems as known/trained.

Shutting down an engine is not a one step process.

Agreed. I am intimately familiar with the process, but thanks anyway for the excellent coverage you presented. I too have done many in sims, taught many in sims, and done it for real a half a dozen times on engines that weren't playing nicely with others.

It is very difficult to imagine how this experienced 3 man crew accidentally shut down the WRONG engine if they followed the correct engine shutdown procedure.

Aye.

[no-hoper]

Uptrim without a reason and no TQ increase.
Autofeather of a nice working engine.

I call it malfunction.

[jommasipi]

The analog Tq meter and the atpcs system get their Tq information from Tq sensors in the engines. If the sensor gives incorrect information this may at least in theory activate the ATPCS and thus the autofeathering of a fully functioning engine. In the FDR picture that I have looked at (http://pbs.twimg.com/media/B9JarHTIAAAgAy3.jpg:large) it seems that the torque of the autofeathered engine was norman until the feathering started. So it seems that the torque has not dropped and thus activated the ATPCS cycle. But there are two differend methods to measure the Tq (I don't remember the other one precicely but it is calculted by the engine control system) and the one that is visible in the FDR tape may not be the same Tq information that is used by the ATPCS.
In ATR MEL it is a normal procedure to turn off the ATPCS system for takeoff and use 100% Tq if the analog Tq meter is not giving correct information. This is because there is a risk that the malfunction is due to broken Tq sensor and it might activate the ATPCS in a fully functioning engine.
If you look at the ITT of the engine #2 it stays at about 400C after the feathering. The engine #1 drops quite quickly to around 150C after it is shut down. To me it seems that the engine #2 was just running on idle and feathered all the time. But power lever of engine #2 was at full power all the time. I have never tried what happenes when you feather an engine with full power in ATR but there might be a logic in the EEC that turns the engine power to idle or near to idle despite that the power lever is in full power.
The situation was most likely confusing. At least in our company we have never simulated inadvertent autofeather in simulator. I don't know what happens in such situtaion.

[Lost in Saigon]

Originally Posted by no-hoper

Uptrim without a reason and no TQ increase.
Autofeather of a nice working engine.

I call it malfunction.

The #1 uptrim was due to the auto-feather on #2. There WAS an increase in Torque on #1 from 90% to 100%.

#2 was not working properly, that is why it auto-feathered. It is all in the data:

ITT dropped
NP dropped
Fuel Flow dropped
Torque dropped
NL dropped
NH dropped

[noalign]

So how does it Uptrim, Autofeather and close the live bleed before a loss of torque. Is loss of torque still the ATPCS trigger in the -600?