Go Back  PPRuNe Forums > Aircrew Forums > Rotorheads
Reload this Page >

Broward County accident...

Rotorheads A haven for helicopter professionals to discuss the things that affect them

Broward County accident...

Old 10th Sep 2023, 07:32
  #161 (permalink)  
 
Join Date: Mar 2012
Location: steady
Posts: 382
Received 3 Likes on 3 Posts
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
Does not sound like a textbook engine failure?
whoknows idont is offline  
Old 10th Sep 2023, 10:51
  #162 (permalink)  
zaq
 
Join Date: Jun 2004
Location: ireland
Posts: 2
Likes: 0
Received 6 Likes on 1 Post
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"
zaq is offline  
Old 10th Sep 2023, 13:11
  #163 (permalink)  
 
Join Date: Apr 2000
Location: EGDC
Posts: 10,320
Received 622 Likes on 270 Posts
Does not sound like a textbook engine failure?
No, so why would he treat it like one?

Zaq - ​​​​​​​Comp stall is usually more than one bang.
crab@SAAvn.co.uk is offline  
Old 10th Sep 2023, 14:57
  #164 (permalink)  
 
Join Date: May 2002
Location: Downeast
Age: 75
Posts: 18,285
Received 500 Likes on 208 Posts
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.



SASless is online now  
Old 10th Sep 2023, 18:08
  #165 (permalink)  
 
Join Date: Oct 2018
Location: South West
Posts: 296
Received 21 Likes on 17 Posts
Originally Posted by SASless
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?
Now that causes me to remember another accident where there are a lot of parallels. It was an EC145 (same cockpit with CPDS) but different engines. There were two incidents where an oil pipe got blocked by coking (insufficient cool down post flight) and oil was starved from a rear bearing on the engine. The bearing temperature went through the roof from friction and one symptom was a TOT rise without any appreciable change in either N1 or torque. The first incident resulted in an engine fire (first parallel) (see here - EC145 has seized bearing leading to engine fire. The second resulted in an engine failure (see here Loss of EC145 following loss of oil and rapidly rising TOT) - it was significantly made worse because the pilot shut down the wrong engine.

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).
gipsymagpie is offline  
The following users liked this post:
Old 10th Sep 2023, 18:15
  #166 (permalink)  
 
Join Date: Oct 1999
Location: Den Haag
Age: 57
Posts: 6,245
Received 330 Likes on 183 Posts
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?
212man is online now  
Old 10th Sep 2023, 18:51
  #167 (permalink)  
 
Join Date: May 2002
Location: Downeast
Age: 75
Posts: 18,285
Received 500 Likes on 208 Posts
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!
SASless is online now  
Old 10th Sep 2023, 19:50
  #168 (permalink)  
 
Join Date: Sep 2022
Location: Florida
Posts: 34
Likes: 0
Received 7 Likes on 5 Posts
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.
helichris is offline  
Old 10th Sep 2023, 19:53
  #169 (permalink)  
 
Join Date: Nov 2006
Location: After all, what’s more important than proving to someone on the internet that they’re wrong? - Manson
Posts: 1,841
Received 51 Likes on 36 Posts
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.
Correct and that's why training / understanding the FLI is essential and simulation is worth it's weight in gold. Reading the digital values is the key. Ng - Q - TOT and where the rectangle is adjacent to plus there is a coloured underline when in yellow or red range which will flash as appropriate.

Why would you have retarded the good engine?
Split FLI needles? "Usually" the one indicating higher is assumed to be the good one?

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
RVDT is offline  
The following 2 users liked this post by RVDT:
Old 10th Sep 2023, 20:40
  #170 (permalink)  
 
Join Date: Mar 2023
Location: Barcelona
Posts: 7
Likes: 0
Received 0 Likes on 0 Posts
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?
helithree is offline  
Old 10th Sep 2023, 21:36
  #171 (permalink)  
 
Join Date: Apr 2000
Location: EGDC
Posts: 10,320
Received 622 Likes on 270 Posts
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.
crab@SAAvn.co.uk is offline  
Old 10th Sep 2023, 21:39
  #172 (permalink)  
 
Join Date: Dec 2006
Location: UK and MALTA
Age: 61
Posts: 1,297
Likes: 0
Received 18 Likes on 4 Posts
[[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%.



DOUBLE BOGEY is offline  
Old 11th Sep 2023, 00:45
  #173 (permalink)  
 
Join Date: Jan 2020
Location: California
Posts: 21
Received 1 Like on 1 Post
Originally Posted by DOUBLE BOGEY
After that, IF the fire warning is active, (the pilot states Yes) then the fire bottle should discharge when N1 drops below 50%.
Why does it not fire until 50%? I don't understand the mechanics of that.
LTP90 is offline  
Old 11th Sep 2023, 00:50
  #174 (permalink)  
 
Join Date: Oct 2009
Location: Australia
Posts: 119
Received 33 Likes on 19 Posts
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.
SLFMS is offline  
Old 11th Sep 2023, 01:02
  #175 (permalink)  
 
Join Date: Nov 2006
Location: After all, what’s more important than proving to someone on the internet that they’re wrong? - Manson
Posts: 1,841
Received 51 Likes on 36 Posts
Originally Posted by LTP90
Why does it not fire until 50%? I don't understand the mechanics of that.
If the engine is still running it is unlikely that you will extinguish the fire. i.e. a leak at the flow divider or nozzle manifold burst.

Hence the logic to try and make it shall we say "idiot" proof.
RVDT is offline  
Old 11th Sep 2023, 01:23
  #176 (permalink)  
 
Join Date: May 2002
Location: Downeast
Age: 75
Posts: 18,285
Received 500 Likes on 208 Posts
SLFMS is spot on ;when he said.....
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.

​​​​​​​

SASless is online now  
Old 11th Sep 2023, 01:26
  #177 (permalink)  
 
Join Date: Nov 2006
Location: After all, what’s more important than proving to someone on the internet that they’re wrong? - Manson
Posts: 1,841
Received 51 Likes on 36 Posts
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….
Centre position? Are you flying an AW109?
RVDT is offline  
Old 11th Sep 2023, 01:30
  #178 (permalink)  
Thread Starter
 
Join Date: Oct 2006
Location: USA
Posts: 751
Received 24 Likes on 19 Posts
Originally Posted by LTP90
Why does it not fire until 50%? I don't understand the mechanics of that.
50% N1 is the point the engine can self-sustain combustion and run without external assistance. The start sequence also shuts off at 50% N1. So for the extinguisher system to have full effectiveness it's activation is delayed until the N1 is below that self-sustain level.

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.
wrench1 is offline  
Old 11th Sep 2023, 02:08
  #179 (permalink)  
 
Join Date: Oct 2009
Location: Australia
Posts: 119
Received 33 Likes on 19 Posts
Originally Posted by LTP90
Why does it not fire until 50%? I don't understand the mechanics of that.

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.
SLFMS is offline  
Old 11th Sep 2023, 03:05
  #180 (permalink)  
 
Join Date: Oct 2009
Location: Australia
Posts: 119
Received 33 Likes on 19 Posts
Originally Posted by RVDT
Centre position? Are you flying an AW109?
No not 109, perhaps inactive position would have been better choice of words
SLFMS is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.