TransAsia in the water?

[parkfell]

Mad Jock post at 1158 hits the nail on the head.

Tim Allan's observations / article about loss of power must now be critical reading and teaching to turbo prop crews.

I found, if memory serves, that zero thrust on Saab 340 is about 30 TQ.?
No doubt DB6 will keep me right !

Therefore any torque less than this zero thrust setting will create DRAG, and must be dealt with without delay.

Must be included in the simulator as a teach and practice. Auto feather failure is difficult to deal with even when you know it is on the agenda. Control and secure practice is essential.

[mad_jock]

A Vmca roll would come after a significant climb rate

Unfortunately not, you can get it while decending as well. It doesn't matter to be honest what your doing if your going down or up as soon as your speed comes back it bites.

The larger the angle of bank the greater the speed as well. Once you go past about 10 degrees the Vmca increases rapidly in a none linear manner.

[Glassy Water]

Unfeathered Prop

I fly the Caravan - with an unfeathered prop it flies as if you have just jettisoned the wings - the rate of descent is horrific. Feathered, the thing flies on forever !

[mad_jock]

My type won't NTS or auto feather what ever you want to call it until it senses negative torque.

Which is 10-15% below the zero thrust setting/feathered

[Lost in Saigon]

Originally Posted by msjh

A couple of random thoughts

All transport category aircraft are certified to fly after a failure of one engine.

Your brother's CASA must have been too heavy for the airport temperature and altitude on that particular day. That is a performance calculation problem. It is not the fault of the aircraft.

There are many factors which can limit the performance of an aircraft. (overloaded, too hot, too high, improper Center of Gravity, etc) Some of these factors could be at play with this ATR-72 crash as well.

One of the most difficult things a pilot trains for is an engine failure right at liftoff. Some pilots are better than others at this maneuver.

The investigation may prove otherwise but my gut feeling tells me the pilot did not handle the aircraft properly following an engine failure.

[mad_jock]

thing is....

I have never heard of a turbine turbo prop engine failure that is anything like what you get in the sim.

I have had first hand storys from pilots not just reading the reports.

They have had rear compressor failures metal coming out the back EGT's through the roof.

They have had the spline couples go between the prop and gear box.

They have had the compressor suck a bird and start surging.

They have FEDEC's go nuts.

Engines that start cycling between 0 and 100% torque.

prop governors not governing.


But never a bang at V1/Vr and then the engine winds down all very well behaved.

[Jet Jockey A4]

Not much left of the aircraft forward of the wing, indeed even the wing is pretty much non existent. However this could be in the way they strapped the aircraft to get it out of the water

Surprised anyone survived the crash.

[Trackdiamond]

in flight Lo Pitch or ATPCS failure

I would like to present these two possible scenarios with ATPCS failed compounded with Eng Flame out.If not reacted to properly in the second segment climb..performance would be severely diminished, this added to posiible mishandling and eroding speed below Vmca...possibly leading to the loss of control we saw depicted in the video sequence.58 people is not a full load on an ATR 72 and for performance to be diminished like that Lo Pitch and or ATPCS might have played a critical role.The assymetric drag experienced during LO pitch if prop not feathered is worse than during engine flame out.It is a Memo item! ATPCS provides for(apart from torque boost on the live engine) auto feather on the engine suffering power loss.So if ATPCS failed...you take matters in your hands..and deal with it swiftly or brace!

[mad_jock]

its not even that warm there just now.

Min 14 deg max 18 in the last 36 hours.

Wind under 15 knots.

[I-NNAV]

Just For info, if -600 is the same as -500 you don't need negative torque on the ATR but Tq< 18%, and prop isn't going to feather if you don't have the pwr management selector on T/O... like when you are above minimum acceleration altitude...

[papershuffler]

Regarding CRM: the pilot (according to news reports) issued a Mayday, therefore managed to graduate to the Communicate part of ANC.

Bearing in mind the timescale, apart from Sullenberger, is there a record of this happening in similar circumstances?

[mad_jock]

I-NAVV what is your zero thrust torque?

[maxed_out]

Crappy aircraft

In my view the ATR is a huge compromise. Underpowered and poorly designed. How they got the "double pull" procedure approved is really beyond strange.
The only benefit of the ATR is that it gets 70 ish people into the air as cheap as possible. Compared to the SAAB 2000:s 4152 SHP the ATR 72-600 is, with it's 2475 SHP, quite underpowered. Bear in mind that they have roughly the same MTOM (ATR 200 kg lower).

Some ATR driver might also shed some light to the engine problems the ATR fleet has had in recent times. Something about massive propeller vibrations?
Maybe the cause of this accident?

[I-NNAV]

For simulated oei ops in manuals is reported only a Power lever angle 39* not a torque, but if you consider that for a 3* glide slope you fly around 22 Tq roughly (not sure, I don't follow the Tq a lot like other colleagues) I don't consider a TQ above 18% an high drag setup...

[mad_jock]

More than likely because it isn't and they chose that number for the auto feather to trigger because to go below that you would be into the drag zone.

Whats flight idle?

[340drvr]

I know nothing about the ATR, but, can these engines experience a runaway torque conditon like the PT-6 in a King Air? Maybe the left engine was OK, while the right side was screaming past redline? That scenario in King Air sim is one of the hardest to recognize and handle properly.

[Trackdiamond]

I-NNAV

If you have flown the ATR you will understand the meaning of Lo Pitch fail and ATPCS failure impact on take off performance.Swift manual feathering would have been required to comply with second segment climb.It might be whilst trying to do that and arrest descent rate they eroded speed and fell below Vmca..that is the scenario am eyeing upon and hope when reports are released to confirm or cofound it.Any ATR 72-600crew in here please can you shed any ligh t on this.

Dispatch with ATPCS u/s or off requires:
Bleeds off

Increase V1 limited by Vmcg by 5kts
Incr Vr by 2kts
Increase Vmca by 3kts
Decrease max 2nd segmet weight by....3600kg in case of ATR 72
For Approach increase Vmcl by 3 kts

So if any of the above were breached in an ATPCS unavailable scenario you can see the performance impact.

[Trackdiamond]

recovery from a stall or abnormal roll control

Control wheel..Push firmly
*if flaps zero(extend flaps to 15)
*if flaps 15 (likely case):
Pwr management ...TO
CL/PL......................MCT
ATC........................notify (May day! in this case...cose to the ground).

Note..This procedure is valid whatever the LDG GEAR position (down or up..in this case UP)

Note that the narrative is based on ATR 500 series.I wonder what the diff would be with 600 series checklist.

[Trackdiamond]

340drvr and prop overlimit

There is a short in flight troubleshoot procedure after retyrding TQ to about 84% and see if the Np increased is below 101% (in whic case continue flt normally

Or if Np remains. Above 101% and conditions permit..shut down the affected engine and follow S.E. ops QRH procedure.

*red limits must not be deliberated exceeded.

I don't think this was the scenario.

[Trackdiamond]

Auto feather tq triggers

For PW121A eng. It is <18%
For PW127E/127M is is <21%

FI PL position is 37 degrees PL angle. The thrust will depend on Atmospherics and EEC regulation that moment.