Engine Fire Indication Caused by Exhaust Gases

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pelmet
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Engine Fire Indication Caused by Exhaust Gases

Post by pelmet »

This was an interesting situation. I assume the crew did the engine fire test to ensure that the system was still operable and ensure that they were not is a situation where a fire has damaged the warning system, resulting in the crew believing that the fire is extinguished when it is in fact still burning.

C-GKFF, a Convair 580 operated by Kelowna Flightcraft Air Charter Ltd., was conducting flight
KFA579 from Vancouver Int’l (CYVR), BC to Kamloops (CYKA), BC with two crew members on
board. Shortly after departure from CYVR, the flight crew observed a fire warning light for the
number 1 engine (Allison, 501-D13D). The power was reduced on the affected engine, the warning
light extinguished. The crew conducted a successful fire warning test to confirm integrity of the
system and elected to return to CYVR. The flight crew completed an uneventful landing and taxied
to the apron.

After the aircraft was parked and the engines shut down, the crew were advised by maintenance
that there was smoke was coming from the wheel well area and were instructed to discharge fire
bottle. ARFF vehicles were requested and attended the aircraft to ensure there was no fire.
On inspection, it was determined that a clamp associated with the number one engine exhaust
duct had failed, allowing hot exhaust gases to be directed at the fire sensors. The flight was
cancelled, the clamp was replaced, and the aircraft was returned to service.
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Last edited by pelmet on Wed Dec 22, 2021 11:48 am, edited 1 time in total.
Big Pistons Forever
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Re: Engine Fire Caused by Exhaust Gases

Post by Big Pistons Forever »

This is a well know issue in the CV580. It is specifically covered in training and the post title is misleading, there was no fire, just that the failed exhaust clamp allowed escaping exhaust gases to set off the detector
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pelmet
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Re: Engine Fire Caused by Exhaust Gases

Post by pelmet »

Big Pistons Forever wrote: Wed Dec 22, 2021 10:33 am This is a well know issue in the CV580. It is specifically covered in training and the post title is misleading, there was no fire, just that the failed exhaust clamp allowed escaping exhaust gases to set off the detector
You are correct about the title. I should have put indication in it. That is now done.
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Re: Engine Fire Indication Caused by Exhaust Gases

Post by PilotDAR »

Back in the early '80's one of our DC-8's departed Belfast for Toronto. On climbout, the crew got a fire warning on the number 2. First action was to reduce the power to number 2, which extinguished the warning. While considering a fuel dump and return to Belfast (where we had no maintenance capability), the Flight Engineer (who was a genuine AME for the type) started diagnosing the problem. They found the partial power setting which produced no fire warning, and checked that all of the other engine indications were appropriate, and they were. so after some circling Ireland, and thinking on it, they decided to fly it home on 3 1/2 engines. The flight was perfectly fine.

I was on the ramp when it arrived, and they opened the cowls. The combustion chamber had deformed a little, and there was now a gap at one of the fuel nozzle mounting points, which allowed hot exhaust gasses to escape, and set off the fire warning. Reduced power = reduced gas and temperature, and no warning. The engine heeded a change anyway, but there was no other damage.

Whether Transatlantic under those circumstances was the ideal decision could be argued either way, but this was one of many occasions I recall where the value in carrying an actual flight engineer was apparent.
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Re: Engine Fire Indication Caused by Exhaust Gases

Post by pelmet »

It is interesting that both incidents caused damage. Something to consider.
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Re: Engine Fire Indication Caused by Exhaust Gases

Post by Scuderia »

pelmet wrote: Wed Dec 22, 2021 12:42 pm It is interesting that both incidents caused damage. Something to consider.
For clarity, and in both examples (CV580 and DC-8), what do you consider the "incident" and "damage"?

You might have the cause and effect reversed.
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Re: Engine Fire Indication Caused by Exhaust Gases

Post by pelmet »

Scuderia wrote: Sat Dec 25, 2021 9:58 pm
pelmet wrote: Wed Dec 22, 2021 12:42 pm It is interesting that both incidents caused damage. Something to consider.
For clarity, and in both examples (CV580 and DC-8), what do you consider the "incident" and "damage"?

You might have the cause and effect reversed.
I think you are correct about the cause and effect being reversed although there was smoke coming from the wheelwell area on the Convair incident(or would 'event' be a better term? Thanks.
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Re: Engine Fire Indication Caused by Exhaust Gases

Post by PilotDAR »

In the case of the DC-8 engine event I described, though the combustion chamber was deformed, this was not presumed to be damage resulting from a fire, there was no fire, just a lot of precombustion, very hot air flowing around inside the cowl where it should not have been, and setting off the fire sensor. They flew back from Belfast with the engine developing some power the whole way.
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Re: Engine Fire Indication Caused by Exhaust Gases

Post by pelmet »

PilotDAR wrote: Sun Dec 26, 2021 10:29 am In the case of the DC-8 engine event I described, though the combustion chamber was deformed, this was not presumed to be damage resulting from a fire, there was no fire, just a lot of precombustion, very hot air flowing around inside the cowl where it should not have been, and setting off the fire sensor. They flew back from Belfast with the engine developing some power the whole way.
So the hot air caused the damage in the DC-8 and possibly the sole in the Convair. So perhaps I as right…..but certainly worth considering the opposite.
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Re: Engine Fire Indication Caused by Exhaust Gases

Post by PilotDAR »

So the hot air caused the damage in the DC-8
The hot air caused the fire warning. The source of damage for the deformation of the hot section which resulted in the hot air escaping is unknown, though not evidently a fire, nor associated with the fire warning. The noteworthy aspect was that the engine ran quite happily below the threshold where the fire warning was triggered, and was still available to produce some power.
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