Engine fire B737-300/900 QRH procedure

[downwind]

Hi All

Appreciate if I could get some opinions on this procedure..... Based on the B737 QRH....................

step 5

"If the engine fire switch or ENG OVERHEAT light is
illuminated:

Engine fire switch . . . . . Rotate to the stop and hold for 1 second
If after 30 seconds the engine fire switch or ENG OVERHEAT light stays illuminated:

Engine fire switch. . . . . . . .Rotate to the other stop and hold for 1 second

In the first instance when does the timing start for the 30 seconds then????.......

this is not clear in the QRH is this after confirmation of the fire bottle "DISCHARGE LIGHT has illuminated"???

thank you.

[B737SFP]

Well... I don't think that waiting more 10 or 15 seconds will do any further harm to the engine.

I just wait for the bottle discharge light to come on, then start the clock.


:}

[NGFellow]

Wait 30 seconds before discharging the second bottle. After rotating the Engine Fire Switch, always verify that the related BOTTLE DISCHARGE amber light illuminates. Therefore, the timing starts after you have confirmation that the first agent was discharged.

[PT6Driver]

The logic being that you allow 30 sec for the agent to do it's stuff, therefore the timing has to start at successful discharge. This will also lead you into confirmation that turning the handle has worked!

[Mach E Avelli]

Whether you timed 28 seconds or 32 seconds, in real life it does not matter. In the sim even the most anal checker won't pick the difference, and even if he did what will he do - fail you?
In typical simulator scenarios, after the second bottle is gone the fire will either go out if the intention is to continue flying, or you will still be burning if the sim instructor wants you back on the ground quickly.


In real life if the fire warning goes out - whether after the first bottle or second bottle - assume nothing. Do a fire warning system test. If it does not test there is no guarantee that the fire is out (personal experience, related elsewhere in these forums). If you have reason to believe that fire is still present, land, NOW...if that means there is only time for speedbrake armed, gear down, flaps 15, add 15 knots, cabin alerted, so be it.

[flyburg]

I think the OP meent something different, if you have to wait 30 seconds before you discharge the first bottle. The checklist covers 3 scenarios( actually four if you count the engine overheat light that directs you to this checklist if the overheat light does not go out), engine fire or severe damage or separation. In the last 2 you might not have a fire warning light.

If you have an engine fire, after you pull the engine fire switch and the the light stays on(which it probably will), you immediately discharge the bottle. Then, after 30 seconds, you discharge the second. You don't wait for thirty seconds after pulling the fire switch to see if the fire goes out by itself before discharging the first bottle.

[downwind]

Mach E Avelli

As a side note...

"In real life if the fire warning goes out - whether after the first bottle or second bottle - assume nothing. Do a fire warning system test." I never knew this from a practical point of view.... do you mean to conduct the Supplementry procedures in the FCOM section 8???????????.......:confused: please explain the meaning of what you wrote I am a bit unsure by what you mean and what are you looking for in the test.....

thank you

[Centaurus]

real life if the fire warning goes out - whether after the first bottle or second bottle - assume nothing. Do a fire warning system tes

Sound advice indeed. It is called Airmanship; a term few people have heard of nowadays:ok:

[Tom!]

As a side note...

"In real life if the fire warning goes out - whether after the first bottle or second bottle - assume nothing. Do a fire warning system test."

I never knew this from a practical point of view.... do you mean to conduct the Supplementry procedures in the FCOM section 8???????????....... please explain the meaning of what you wrote I am a bit unsure by what you mean and what are you looking for in the test.....

thank you

You want to test the integrity of the detection system. Did the warning light go out because of the fire being extinguished or the detection system being burned through?
If the test fails the fire might still be there, if it still works and the light comes on :D

[Mach E Avelli]

No one is likely to fail a simulator check if they ONLY complete the items as per the FCOM, but then no one is likely to fail for applying extra precautions.
We should not be treating simulator exercises any differently to the way we would act in a real emergency. It appears that I am not alone in running a fire test after any fire drill.
But no, neither I nor other examiners I know REQUIRE it, because so far it has not found its way into the QRH.
Having said that, were you to dispute or belabour good advice you probably would do yourself no favours when the examiner graded the non technical skills section on your check form.

[Derfred]

I don't call that Airmanship.

I call that Making **** Up.

Boeing specifically recommends against further troubleshooting unless the situation is beyond the scope of the QRH.

Do the checklist and land the aircraft. Don't make **** up.

[lomapaseo]

We should not be treating simulator exercises any differently to the way we would act in a real emergency. It appears that I am not alone in running a fire test after any fire drill.

going beyond the check list?

if so what are the resulting actions to be based on the result?

[mini-jumbo]

In real life if the fire warning goes out - whether after the first bottle or second bottle - assume nothing. Do a fire warning system test. If it does not test there is no guarantee that the fire is out (personal experience, related elsewhere in these forums). If you have reason to believe that fire is still present, land, NOW...if that means there is only time for speedbrake armed, gear down, flaps 15, add 15 knots, cabin alerted, so be it.

Disagree with you there, irrespective of whether the indication goes out or not, or if you believe the fire to be out - you land ASAP, as per the QRH. Even if the fire goes out, you have no way of assessing the damage.

Wasting time performing a fire test (albeit seconds) is just that, wasted time. It could also lead you into a situation of confirmation bias, where you now believe the fire is out and have more time that actually do.

[Mach E Avelli]

Of course you should land ASAP whenever the QRH says so! Has anyone suggested otherwise?
But often in the simulator we see crews who don't apply any sense of urgency to a situation when cues are given to them that the damage really is a threat to their existence. A good one is to throw in a fuel leak, such as could be caused by shrapnel from the engine going through the wing. Some crews are quite happy to head for the holding pattern for a detailed approach briefing, all the while losing fuel at an alarming rate.
Others will blithely start cross feeding to the good engine even though the asymmetry is all wrong. Some will go for a full approach with the fire warning still illuminated, rather than cut it short. One can only hope that in a real situation fear for survival would trigger more decisive action.
I won't relate in detail my personal experience on another type with a similar fire detection system to the older Boeings here, as it is to be found elsewhere. Suffice to say, new aircraft out of the factory only a week, faulty combustion chamber, very intense flame, warning system disabled within seconds, leading initially to thinking perhaps the warning was spurious. Fortunately fire was visible from the cabin so both bottles were discharged despite no warning in the cockpit. From the initial very short indication to recognition that it was for real, to action commencing was less than a minute, yet considerable damage was done, including almost burning through some vital engine control linkages.
Some years later I had the pleasure of completing a Type Rating with an American Check Airman who had flown in excess of 30,000 hours. This guy had done a lot of work on early wind shear escape techniques for jet aircraft, so was no student pilot big on theory small on practice. During simulator training he also recommended a fire test after the drill. He had either experienced a similar event, or thought about the possibility.
The QRH does not call for cabin crew to be asked to look for signs of damage either, but if you had a fire/severe damage situation, after completing the drill would you not have someone look and report or send the F/O back if workload permitted? The QRH is only one part of managing emergencies and certainly does not prohibit further investigation, though of course one would be ill advised to start throwing extra switches or resetting circuit breakers.
After a fire or severe damage drill, if crew reported that they could not see anything would that be confirmation bias? Only for someone who subscribed to the notion that ignorance is bliss. Most would still land ASAP, as per QRH. However, if fire was visible or fuel was everywhere except in the tank the term ASAP could take on a whole new degree of urgency.

[vapilot2004]

Been reading this one and had nothing to add - until now and that is to say I agree with Mr. Avelli. The more information at hand, the better equipped you are to handle a situation, whatever that may be.

Now there is a possibility of information overload - something that happens with automation these days when the computers can't settle in on the problem, but that's another kettle of cod.

[riff_raff]

Interesting discussion. I'm not a pilot, but I am an engineer with experience designing commercial aircraft propulsion systems.

There are extensive fire detection instrumentation systems inside the nacelle of a commercial aircraft like a 737. But most nacelle fires are due to severe engine damage, and they are often fed by oil or fuel leaks. It is difficult for the fire suppression systems to extinguish these fires.

On the other hand, the engine pylon and engine systems are designed to survive largely intact for a 20 minute exposure to a nacelle fire.

[TheiC]

It's always best to know the status of our machines. That, in my mind, includes an evaluation of the engine after a fire, severe damage, or separation event.

A consequence of training for this in simulators is that things one could, and arguably should, do, in the aircraft, are not possible. For example, in a reject for an engine fire, and after the appropriate drills, I would get the cockpit window open and lean out and have a look (or ask my copilot to do so if it's on his side). When airborne, and assuming one doesn't have the misfortune to be flying a loaded freighter or at night, a visual inspection, ideally with images taken from the cabin with an iPad or similar, may be of great value.

That aside, I would agree with most of what Mach has written, but also hold the advice about making stuff up in high regard.

I can't help thinking that simulators with windows that can open, and some system of showing whats going on outside, might be valuable training aids. I know one TRE who has some photoshopped images on his iPad, showing engines in various states of disrepair, viewed from the cabin.

[Oakape]

There is a huge difference between 'making stuff up' & maintaining a healthy suspicion of what is being presented to you.

I have found that many seem to be very happy to take the information presented by the aircraft systems as gospel these days & don't bother to check & cross-check. "Don't worry - the aircraft will tell you when something is wrong" seems to be the modern mantra. They seem to be content to deal with the issue when it becomes a problem, rather than head it off before it becomes a problem. Maybe I am old fashioned, but I call that a lack of airmanship.

[Derfred]

There is a scripted checklist for an engine fire. It wasn't dreamt up overnight.

If Boeing felt there was value in running a system test during that checklist, then they would say so. They don't. In fact, they say the opposite in the QRH introduction.

Prior to running a system test, good CRM directs that you first explain to the other pilot what you are about to do, and not do it until he/she is comfortable with it. Since you are going outside the checklist, good CRM directs that the other pilot will very likely question your actions and you will have to explain further. "Why are you conducting troubleshooting - we haven't even finished the checklist yet." The will result in distraction from the emergency at hand, cause possible delay to continuing the checklist and landing the aircraft, and (worst case) may result in you performing actions adverse to the continued safety of the aircraft due to conducting un-rehearsed and non-recommended actions to the amazement of the other pilot.

[ACMS]

I've never EVER been trained by Boeing OR Airbus OR Fokker to conduct a test of the Fire system during an Engine Fire warning or indeed after the warning stops.......

NO NO and NO.

FOLLOW THE BLOODY QRH NNC....

Land that Plane Maverick.....


I mean really.....

After the warning stops you conduct a test:---

1/ normal test result
or
2/ test fail

What does it mean anyway????? If the fire is out then do the loops reset?? I don't know???
Do you know???

Like I said, land the damn plane ASAP considering all factors relevant, it won't change your situation will it???

[vapilot2004]

Training, in this case, covers the possibility of the detector system not being a perfect indicator of whether the fire's been quenched or not. There may not be a procedure, but gathering information is not prohibited. Why not see what say the loops post discharge?

The delay between bottle discharge is due to the slow reaction of the loops. They are gas-filled metal tubes connected to (sometimes overly sensitive) pressure sensors and the system can take a few moments to recompose after being torched by burning kerosene or engine oil.

[Oakape]

I don't believe that anybody is advocating running a fire system test in the middle of the memory items, or interrupting a checklist to do so. The suggestion was to do the fire test at some stage after the fire warning has ceased, in order to ascertain whether the fire has indeed been extinguished or perhaps the warning has stopped for other reasons. This is something I have never heard of before & never considered, but it does make a lot of sense to me after thinking about it for a while.

Perhaps some should endeavour to step away from the trees & take a look at the forest. And don't always hang your hat on the training you have received. Sometimes it is a case of the blind leading the blind. The status quo is not always correct & it is often wise to consider new things objectively, rather than just repeating the mantra - "we have always done it that way"

[ACMS]

It does not make any sense to makeup your own checklists or such, what you think Airbus Boeing and Fokker didn't think of this? They don't deem it necessary.

The only time I might consider a test is if the Fire Warning came on for a few seconds and went out before I started the recall items. Then I might just ask myself what's going on and perhaps perform a test.

I just hope I'm not faced with that scenario, especially en route miles from the nearest Airfield.

[Capt Quentin McHale]

vapilot2004,


I believe there is another fire detection system consisting of dual loop detectors consisting of Inconel tubes filled with a salt impregnated ceramic core and a Nickel wire. An AC power supply is connected to the Nickel wire and the Inconel tube is grounded. At low temps, the resistance of the core is high and the capacitance is low.


When the temp increases to a certain set temp along the length of the Fire Detector or a higher set temp along say 30cm of the detector, the resistance decreases and the capacitance increases allowing current flow to ground and actuating the Engine Fire Indication.


McHale. :)

[vapilot2004]

Thank you Cap!

The following is anecdotal evidence from one of our crustiest engineers. (Take with a few grains of salty ceramics?)

Gas loops are prone to false alarms, says he, due to their sensitivity and the placement calibration, but are less likely to fail a BITE test. Inconel (or capacitive Kidde) loops are fragile and can be a pain in the keester (his word) to install unmolested, however they tend to produce fewer false alarms.

Our guy was unable to say definitively which loops are installed on which airplanes, but I assumed the gas loops are on newer NGs and the Inconel goes all the way back to the Jurassic, but do not know this to be absolutely true.

Any chance you might? Cheers!

[Capt Quentin McHale]

vapilot2004,


Our engineers can definitely confirm that I too am from the Jurassic period, but with regards to the fire loops, they seem to think that it could be either operator specific or manufacturer specific. Hope this helps.


McHale. :)

[Trash8mofo]

On a related question, say the fire warning light came on and you pulled the thrust lever back, then the warning light went back out. Would you continue the memory items per QRH or leave it at idle power?

[Derfred]

Does the checklist say to discontinue the checklist if the light goes out?

[vapilot2004]

Thank you Capt McHale! You're from the Jurassic era? :ok:


On a related question, say the fire warning light came on and you pulled the thrust lever back, then the warning light went back out. Would you continue the memory items per QRH or leave it at idle power?

Procedure calls for stopping just shy of discharging the bottles.

[downwind]

back to the discussion on the fire test procedure after the fire QRH items have been actioned, can people please tell me if you would test with fault/inop or ovht/fire switch??????? and what are the indications you should be looking for on the overheat/fire protection panel relating to the 737-300/900 type. I am a bit confused about this point that one of the posters is talking about, as of now no one has told has ever told me about this for a FAR 25 style aircraft??

[Mach E Avelli]

Well the fundamentalists will say that there is no requirement to check anything beyond what the bible says because the great God Boeing will ensure that nothing can go wrong go wrong if your prayers are offered up directly from the bible.
The atheists and agnostics among us will say believe in nothing, trust not entirely in God or His bible but cover your arse by checking everything to be sure to be sure.
You are looking for a failed test to indicate the possibility - however remote - that the lack of a warning is no longer confirmation that the fire is truly out.
What you do with that information is beyond the scope of the QRH because that document can not cover every eventuality and does not claim to cover every eventuality. That is why you get paid the big bucks. Anyone can read a QRH and unthinkingly follow procedures.
Capts Haynes and Sullenberger are prime examples of pilots who went beyond the QRH to save lives. There are others like the skippers of the Gimli glider and the topless 737.

[latetonite]

To vapilot2004: almost correct, but no cigar. procedure stops after pulling TL back, if the light goes out.

[Derfred]

Anyone can read a QRH and unthinkingly follow procedures.

Obviously not:

almost correct, but no cigar. procedure stops after pulling TL back, if the light goes out.

[latetonite]

Sorry for the confusion here. I read a few posts above 'engine overheat light', and was answering according the QRH. Read again the posts and discovered people were discussing 'engine fire'.
The memory items are obvious.

[AeroTech]

Hi,

Mack E Avilli, can you explain exactly what Capts Haynes and Sullenberger & the skippers of Gimli gliders and the topless B737 did beyond QRH to save lives?

Are there examples of pilots who went beyond QRH and caused incidents, disasters...?

Feedback appreciated.
Regards

[latetonite]

I am with Mach E Avelli here.
The ones who 'live by' the QRH probably did not read the Introduction section of it.
Airmanship is still an essential, but more and more hard to find part of flying aeroplanes.
To go even further, even SOP's can kill you, if exercised without critical analysis in some circumstances.

[ACMS]

Ok then experts:---

After a real Fire warning where the fire warning has gone out

What's the test supposed to show, Pass or fail?

What do you do if it passes or fails?

Is your thinking different?

Do you decide to hurry up and land or take your time?

Please enlighten me.....:ok:

[Mach E Avelli]

Fire indicated out, test shows warning system still good, it is reasonable to believe fire is out. But check for damage elsewhere anyway and land ASAP. ASAP still implies that you will be landing on an airport that will at least accommodate your aeroplane safely.
Test fails, suspect further damage and consider the POSSIBILITY that there may still be fire and act as if this is the case. It is all about understanding the relative seriousness of the latter possibility compared with the lesser probable risk of the former.
Uncontained fire or very severe damage MAY require a decision to land somewhere quite unsuitable (even unsafe in normal circumstances) but survivable, so could mean re-routing to minimise time in flight should the worst eventuate.
That is what they did with the Gimli glider, though with no fuel it was not likely to burn!
Capt Haynes had to 'invent' a new way of controlling an aircraft with thrust alone. It sure as hell was not in the QRH.
I believe that Capt Sullenberger went straight for the APU before getting into the rest of the QRH. It was out of sequence but they did not have time to work all the way through the QRH so needed to prioritise. Since then Airbus have probably rewritten the QRH but I am not an Airbus person so don't know for sure.

[ACMS]

Sorry mate I don't believe your analysis is foolproof.

The actual Fire that the detectors detected will most likely damage the detectors won't it?
I would expect that the test for that Engine would not pass.
In this case you may be led down the garden path to land at an Airfield you don't really want to be at.

The Airbus ECAM has a RED LAND ASAP with a Fire and that about covers it....

There are other things you will do to ascertain the state of the Fire and :--

LAND ASAP.

I still say that both Airbus and Boeing would have considered this possibility ( everything they do is with litigation in mind and ass protecting ) and decided against it for very good reasons not least being it may not be a reliable check of the system or indicate the level of damage to the Engine.

Oh and yes most definitely there is a time and a place to vary procedures as required, as has been shown many times:ok: ( as indeed Airbus and Boeing advise )

[Mach E Avelli]

Nothing in aviation is foolproof. I would be the last to claim any foolproof analysis skills. In training I merely seek to get pilots thinking outside the square.
A Yank I knew many years ago worked out that Fokker's emergency gear extension drill for the F 27 could fail to do the job under certain circumstances. He wrote to Fokker about it, and offered an alternative procedure. They ignored it. I did not ignore it and in a memo advised my pilots to consider this guy's unofficial drill if the approved drill failed because it made so much sense. Sure enough, one day an aircraft had a problem with the pneumatics and the gear would not come down using the approved procedure. So the pilot did the unofficial drill. It worked.

[ACMS]

Hey after 30 years flying you have me thinking.......:ok:

I hope I'm never faced with the decision...:eek:

[Derfred]

Bit of thread drift here. There will always be situations outside the scope of the QRH. The QRH acknowledges that, and in those situations procedures should be varied as necessary for the best safety outcome.

But that's not the discussion here. An engine fire warning is not outside the scope of the QRH. So, the question is whether to interrupt an engine fire checklist and start testing fire loops (without the other pilot punching you on the nose). I recommend that you don't. So does Boeing - in the QRH introduction that apparently I haven't read. Don't make **** up. And, no, you are not going to put a B737 in a grass paddock just because an engine continues to burn. It's not an F27.

Where it might go outside the scope of the QRH is if there are other simultaneous problems perhaps caused by an engine shredding itself - such as a jammed aileron, hydraulic leak, depressurisation, gear problem, etc. This is where you get to decide on the most appropriate course of action, or priorities of action, using all that experience and airmanship that apparently I don't possess.

[vapilot2004]

So, the question is whether to interrupt an engine fire checklist and start testing fire loops

I am fairly sure no one here is suggesting interrupting memory items, rather after the engine is secured and return to earth plans are made would the test procedure be run.

Here's the thing about that: Pressing the test button may not actually reveal a bad loop as it is only a test of the detection and alarm system, post-loop, not that there's anything wrong with confirming that part of the system. I also wouldn't mind a set of MK I eyeballs looking at the thing from a window.

Apparently, the loops are under regular monitoring by the engine fire detection system - at least on our aircraft. This could be the same situation across the fleet.

Learnt a new thing yesterday, I did. From my perspective, it pays to talk to the gents in the maintenance bay.