Broward County accident...
the pilot heard a “bang” from the rear of the helicopter and noticed that the turbine outlet temperature (TOT) was rising on the No. 1 engine
Would initial diagnosis have been compressor stall - bang, rising TOT? No cause for alarm, not an emergency. Change/reduce power setting, try idle for a while, see if it fixes?<br />Subsequent Fire warning changes diagnosis and heart rate.
Last edited by zaq; 10th Sep 2023 at 10:55. Reason: replace "failure" with "stall"
Does not sound like a textbook engine failure?
Zaq - Comp stall is usually more than one bang.
If one runs with the un-contained catastrophic engine failure causing a high and increasing TOT.....what would you expect the N1/NG to be?
Would moving the ECL to Idle have any effect?
Compressor stall would probably show fluctuations in both TOT and N1/Ng rather than just an increase in TOT (which I take the Pilot was describing....TOT going one direction....up, hot, and staying hot.)
Is compressor stall more commonly a problem during power increases or very high power demand and relatively rare in steady state flight?
Are some of you assuming the account by the pilot in the Preliminary Report a full detailed account of this actions which it most likely is not?
In time we shall be able to compare the Final Report to the Preliminary Report and confirm what the Pilot actions actually were.
One can apply Text Book reactions to Text Book events but if One is encountering a non-textbook failure you might just be making a mistake.
If this was an un-contained compressor failure and there was "shrapnel" damage to fuel lines/feul valves/ fire suppression system or the control systems for them.....it very well was not a text book situation.
That is was anything but textbook is a possiblilty that cannot be discounted.
One thing we can all agree is this was a very unusual occurrence partly because we have both video recordings of the event from "witnesses" and the Pilot who can offer very useful and pertinent information.
Querying the pilot's actions based upon the preliminary report is fair but should consider that it might not be the full accounting of all of his actions.
One explanation of why the Fire. Suppression system may not. have functioned based upon the failed Engine's N1/Ng makes good sense and asking what position the ECL should have been in is also a fair question.
Would moving the ECL to Idle have any effect?
Compressor stall would probably show fluctuations in both TOT and N1/Ng rather than just an increase in TOT (which I take the Pilot was describing....TOT going one direction....up, hot, and staying hot.)
Is compressor stall more commonly a problem during power increases or very high power demand and relatively rare in steady state flight?
Are some of you assuming the account by the pilot in the Preliminary Report a full detailed account of this actions which it most likely is not?
In time we shall be able to compare the Final Report to the Preliminary Report and confirm what the Pilot actions actually were.
One can apply Text Book reactions to Text Book events but if One is encountering a non-textbook failure you might just be making a mistake.
If this was an un-contained compressor failure and there was "shrapnel" damage to fuel lines/feul valves/ fire suppression system or the control systems for them.....it very well was not a text book situation.
That is was anything but textbook is a possiblilty that cannot be discounted.
One thing we can all agree is this was a very unusual occurrence partly because we have both video recordings of the event from "witnesses" and the Pilot who can offer very useful and pertinent information.
Querying the pilot's actions based upon the preliminary report is fair but should consider that it might not be the full accounting of all of his actions.
One explanation of why the Fire. Suppression system may not. have functioned based upon the failed Engine's N1/Ng makes good sense and asking what position the ECL should have been in is also a fair question.
The EC135 FLI on the CPDS is uniquely misleading if you have a runaway TOT and you bring the "good" engine back to idle - it looks like you've done the right thing (the extreme TOT AEO is suddenly not so extreme OEI). You have now loaded up the bad engine and it fails. Very easy to demonstrate on a EC135 simulator.
So I think a blocked oil pipe and seized bearing is a possible culprit (or an uncontained runaway up - although the pilot would almost certainly have commented on this).
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The EC135 FLI on the CPDS is uniquely misleading if you have a runaway TOT and you bring the "good" engine back to idle - it looks like you've done the right thing (the extreme TOT AEO is suddenly not so extreme OEI). You have now loaded up the bad engine and it fails. Very easy to demonstrate on a EC135 simulator.
How would you determine which engine to retard or shut down based upon the indications seen on the gauges?
What would be the indications?
How would you quickly determine what was going wrong?
Ball is in your court 212man!
What would be the indications?
How would you quickly determine what was going wrong?
Ball is in your court 212man!
The FLI screen would have switched from torque to TOT when the bad engine got hot. The pilot may thought he was still looking at torque which made him think the hot engine had picked up the load and then shut down the good engine. The only indication would be a retangle next to whatever engine parameter the gauge is reading (the first limit). There were probably secondary indications on the CAD and warning panel but not sure. Good lesson to not to get in a rush when things go to hell.
The EC135 FLI on the CPDS is uniquely misleading if you have a runaway TOT and you bring the "good" engine back to idle - it looks like you've done the right thing (the extreme TOT AEO is suddenly not so extreme OEI). You have now loaded up the bad engine and it fails. Very easy to demonstrate on a EC135 simulator.
Why would you have retarded the good engine?
The other "classic" in the sim is - engine failure - FIRE indication on the remaining good engine - watch how many reach up to push the FIRE button without hesitation or thinking through the consequences and planning things a little better.
Last edited by RVDT; 10th Sep 2023 at 20:06. Reason: Refinement
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Years ago in Hungary a HEMS 135 crashed because pilot had an engine failure and shut down the working engine by mistake. No survivors.
I haven't flown 135 or similar, but with russian machines you see pretty quickly and clearly which engine is the one to shut down.
I'd like to see the VEMD and gauges as one engine fails in a 135, anyone have a video?
I haven't flown 135 or similar, but with russian machines you see pretty quickly and clearly which engine is the one to shut down.
I'd like to see the VEMD and gauges as one engine fails in a 135, anyone have a video?
The pilot says he saw high TOT on No1 and that was the one he brought to idle. No suggestion of shutting down the wrong engine - just of not shutting down the failed engine.
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[[email protected];11500100]I don't think anyone has an issue with him returning to the field with what ostensibly looks like an engine failure (albeit an explosive one).
It seems that he didn't shut the engine down - just set it to idle - and then subsequently noticed the fire and banged off the bottle. Although it seems the idle N1 would be too high to allow the bottle to discharge.
Elements of the tail boom/TRDS could have been damaged by the engine trashing itself and it might have failed anyway but why didn't he shut the engine down completely?
If he had put it to idle, checked the indications (he said he did this) and then completed emergency shutdown - we probably wouldn't be discussing this as the fire would hopefully have gone out and he would have made a safe OEI landing
crab, I can put this to bed early. Idle provides around 70% N1. Pressing the Emergency fir burrow on the CwP shuts down the engine by closing the fuel valve. After that, IF the fire warning is active, (the pilot states Yes) then the fire bottle should discharge when N1 drops below 50%.
It seems that he didn't shut the engine down - just set it to idle - and then subsequently noticed the fire and banged off the bottle. Although it seems the idle N1 would be too high to allow the bottle to discharge.
Elements of the tail boom/TRDS could have been damaged by the engine trashing itself and it might have failed anyway but why didn't he shut the engine down completely?
If he had put it to idle, checked the indications (he said he did this) and then completed emergency shutdown - we probably wouldn't be discussing this as the fire would hopefully have gone out and he would have made a safe OEI landing
crab, I can put this to bed early. Idle provides around 70% N1. Pressing the Emergency fir burrow on the CwP shuts down the engine by closing the fuel valve. After that, IF the fire warning is active, (the pilot states Yes) then the fire bottle should discharge when N1 drops below 50%.
The other "classic" in the sim is - engine failure - FIRE indication on the remaining good engine - watch how many reach up to push the FIRE button without hesitation or thinking through the consequences and planning things a little better.[/QUOTE]
This one always gets me in the RFM. After securing the fire, return fire system switch to centre position so if there is a fire on the opposite side you can use the system on that side. Big choice removing both your engines (not saying it’s not ever appropriate)
That would be a bad day….
A seizing turbine section is a good failure in the Sim, I’ve seen plenty diagnose that wrong. Good engine looks like low side failure with bad engine taking the load, high ITT etc. N2 is the diagnostic tool
A lot been read into the initial comments by the Pilot. I personally take it with a grain of salt, memory is not reliable in high stress situations. Perhaps Turbine section has let go as N2 drops engine feeds more fuel to keep governed speed ITT/ToT climbs through the roof. Sounds perfectly feasible to me and turbine failure could explain the fire.
I know first hand and discussed with crew after a compressor failure aided by a rag, loud bang follow by very high ITT and secondary bangs pops.
Both loud bangs followed by multiple other bangs with high ITT. Very different failure points.
This one always gets me in the RFM. After securing the fire, return fire system switch to centre position so if there is a fire on the opposite side you can use the system on that side. Big choice removing both your engines (not saying it’s not ever appropriate)
That would be a bad day….
A seizing turbine section is a good failure in the Sim, I’ve seen plenty diagnose that wrong. Good engine looks like low side failure with bad engine taking the load, high ITT etc. N2 is the diagnostic tool
A lot been read into the initial comments by the Pilot. I personally take it with a grain of salt, memory is not reliable in high stress situations. Perhaps Turbine section has let go as N2 drops engine feeds more fuel to keep governed speed ITT/ToT climbs through the roof. Sounds perfectly feasible to me and turbine failure could explain the fire.
I know first hand and discussed with crew after a compressor failure aided by a rag, loud bang follow by very high ITT and secondary bangs pops.
Both loud bangs followed by multiple other bangs with high ITT. Very different failure points.
Hence the logic to try and make it shall we say "idiot" proof.
SLFMS is spot on ;when he said.....
.
Anyone who has experienced a very high stress fast paced event will understand the accuracy of that statement.
A lot been read into the initial comments by the Pilot. I personally take it with a grain of salt, memory is not reliable in high stress situations.
Anyone who has experienced a very high stress fast paced event will understand the accuracy of that statement.
This one always gets me in the RFM. After securing the fire, return fire system switch to centre position so if there is a fire on the opposite side you can use the system on that side. Big choice removing both your engines (not saying it’s not ever appropriate)
That would be a bad day….
That would be a bad day….
And another point on the engine shutdown procedure is if the engine switch is turned OFF and the engine still runs or there still is a TOT increase the final measure is to perform a shutdown via the manual twist grip. I believe there is a mx check to verify the manual shutoff rigging is correct.
It can be unexpected reasons. On the 412 pulling the t handles shuts the fuel valve and energises the fire suppression system.
The procedure requires closing the throttle first, I used to think why? It’s slower, there is more likelihood of selecting the wrong engine and the throttles can be awkward, why not just pull the T handle?
Turns out it relates to the particle separator, it will suck all of your suppressant out of the engine bay. When you shut the throttle it closes the system, the time it takes to continue the SOP after closing the throttle is enough to close the particle separator door.
You could of course pull the T handle (which also closes the particle separator) and wait 10seconds which will achieve the same thing but evidently Bell has decided Pilots who’s aircraft are on fire might not be the best at accurately guessing time and might waste their first fire bottle.