Engine overheat
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Engine overheat
So, had a very interesting day, flying the B737.
During our takeoff roll, we aborted at around 60kts when we got master caution ELEC --> DRIVE, eng nr 2.
After troubleshooting and talking with our company, we were assigned a slot for departure, so we decided to shut down the engines, about 10 minutes after the aborted takeoff.
Slot improved shorty after, so we completed our checklists and were getting ready for a new startup. We started engine number 2 and it was a good start. Planning for single engine taxi, we were about to do the "one engine taxi checklist" when we noticed OVHT/DET on the master caution panel.
Looking down on the fire panel, the ENG 2 OVERHEAT was illuminated. We did the memory items. QRH refers you to go to the "engine fire" NNC since the overheat indication still was illuminated, but since we were on stand and already at idle thrust, we put the engine start lever to cutoff instead.
Talking with our company again, this day was just getting better and better.
The OVHT DET switch at ENG nr 2 was set at NORMAL. The FCOM says that "normally both loops have to sense an overheat condition while engines running" to cause the indication. After shutdown, we changed OVHT DET switch to loop A, and the indication disappeared. Switched it to B, the overheat indication illuminated(this was done a couple of minutes after shutdown). We did the fault and fire test, and there was no indication of any malfunction on any of the loops. The OVERHEAT indication disappeared about 10 minutes after engine shutdown(OVHT DET panel set at Normal).
We did another engine restart and shutdown without pax - also this time, we got the engine overheat indication, but only when selection loop B, unlike the first time, when the detection switch was set to Normal.
We concluded that loop B was fault, as engine indication was normal
Anyway, my point is that we got an engine overheat indication on loop B, despite the loop passing the fault and fire tests. Others had similar experiences?
Taking into account the aborted departure with the drive malfunction, this was a very special experience.
Best regards
Note: The APU were powering both AC busses at startup when we got the engine overheat indication.
During our takeoff roll, we aborted at around 60kts when we got master caution ELEC --> DRIVE, eng nr 2.
After troubleshooting and talking with our company, we were assigned a slot for departure, so we decided to shut down the engines, about 10 minutes after the aborted takeoff.
Slot improved shorty after, so we completed our checklists and were getting ready for a new startup. We started engine number 2 and it was a good start. Planning for single engine taxi, we were about to do the "one engine taxi checklist" when we noticed OVHT/DET on the master caution panel.
Looking down on the fire panel, the ENG 2 OVERHEAT was illuminated. We did the memory items. QRH refers you to go to the "engine fire" NNC since the overheat indication still was illuminated, but since we were on stand and already at idle thrust, we put the engine start lever to cutoff instead.
Talking with our company again, this day was just getting better and better.
The OVHT DET switch at ENG nr 2 was set at NORMAL. The FCOM says that "normally both loops have to sense an overheat condition while engines running" to cause the indication. After shutdown, we changed OVHT DET switch to loop A, and the indication disappeared. Switched it to B, the overheat indication illuminated(this was done a couple of minutes after shutdown). We did the fault and fire test, and there was no indication of any malfunction on any of the loops. The OVERHEAT indication disappeared about 10 minutes after engine shutdown(OVHT DET panel set at Normal).
We did another engine restart and shutdown without pax - also this time, we got the engine overheat indication, but only when selection loop B, unlike the first time, when the detection switch was set to Normal.
We concluded that loop B was fault, as engine indication was normal
Anyway, my point is that we got an engine overheat indication on loop B, despite the loop passing the fault and fire tests. Others had similar experiences?
Taking into account the aborted departure with the drive malfunction, this was a very special experience.
Best regards
Note: The APU were powering both AC busses at startup when we got the engine overheat indication.
Last edited by k738; 27th May 2017 at 20:18. Reason: additional info
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Looking down on the fire panel, the ENG 2 OVERHEAT was illuminated. We did the memory items. QRH refers you to go to the "engine fire" NNC since the overheat indication still was illuminated, but since we were on stand and already at idle thrust, we put the engine start lever to cutoff instead.
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Good question. In my opinion, its allowed to use your head a little bit, instead of acting like a robot. There is no need to be trigger happy, there is normally no rush.
Parked at stand, and with normal engine indication, we decided to stop the memory items at start level cutoff. Switching between loop A and B quickly showed us that only one loop was sensing heat. Doing this, we avoided firing the fire extinguishing agnet into the engine, and able to depart some hours later. With this said, in the air, or after applying power on the engine, we would have done all the fire items immediately. Referring to the QRH, checklist instruction ;
'The flight crew must be aware that checklists cannot be created for all conceivable situations and are not intended to replace good judgment. In some situations, at the captain's discretion, deviation from a checklist can be needed'.
Im sure there is a lot of different opinions on this, which is good. Im my opinion, stop, breathe and think for some secconds is a good thing before acting.
Parked at stand, and with normal engine indication, we decided to stop the memory items at start level cutoff. Switching between loop A and B quickly showed us that only one loop was sensing heat. Doing this, we avoided firing the fire extinguishing agnet into the engine, and able to depart some hours later. With this said, in the air, or after applying power on the engine, we would have done all the fire items immediately. Referring to the QRH, checklist instruction ;
'The flight crew must be aware that checklists cannot be created for all conceivable situations and are not intended to replace good judgment. In some situations, at the captain's discretion, deviation from a checklist can be needed'.
Im sure there is a lot of different opinions on this, which is good. Im my opinion, stop, breathe and think for some secconds is a good thing before acting.
Last edited by k738; 28th May 2017 at 07:26.
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Well, did you do a fire test when you took over the aircraft? The only case when only one loop will trigger an overheat or fire warning is when the other one is detected to be failed (loss of gas pressure or power failure). Were you directed by an engineer to do these steps? I would have done a bit of troubleshooting myself as well to get her going, so I don't want to question your course of action, but a recurring overheat warning is a little bit too serious for my taste - especially because having normal engine indications otherwise are no guarantee of not having an abnormal situation (you could have a had a bleed leak, or worse...)
Engine overheat can be somewhat of a misnomer. It is not inside the engine per se, but within the cowlings or the strut (pylon). Most likely bleed leak, but in worst case could be hot air leak from the engine casing (this would probably indicate serious damage).
That said, after the first start I would have given the airplane to maintenance.
That said, after the first start I would have given the airplane to maintenance.
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Referring to the QRH, checklist instruction ;
'The flight crew must be aware that checklists cannot be created for all conceivable situations and are not intended to replace good judgment. In some situations, at the captain's discretion, deviation from a checklist can be needed'.
Im sure there is a lot of different opinions on this, which is good. Im my opinion, stop, breathe and think for some secconds is a good thing before acting.
'The flight crew must be aware that checklists cannot be created for all conceivable situations and are not intended to replace good judgment. In some situations, at the captain's discretion, deviation from a checklist can be needed'.
Im sure there is a lot of different opinions on this, which is good. Im my opinion, stop, breathe and think for some secconds is a good thing before acting.
There's a lot written about troubleshooting in Boeing's manuals, worth a read.
Parked at stand, and with normal engine indication
So, two failures on the same engine. At what point did the engineers/mechanic/Tech etc open the cowling to investigate? Chafing of wiring on the structure used to be a common fire loop fault on the 737 classic.
Reading between the lines no engineering involvement at the aircraft ? Say no more ! Luckily i work in an outfit where a return to stand would have to result in a logbook entry and sign off by an LAE even if it was 'reset satis' !
How come you didn't do the checklist for DRIVE light?
I know of a DRIVE light coming on which was the first indication that a mechanical failure was about to cause havoc in the engine, the engine failed fairly spectacularly a wee while later.
Personally I don't agree with your interpretation of the Boeing philosophy regarding making checklist items optional unless there are extenuating circumstances.
I know of a DRIVE light coming on which was the first indication that a mechanical failure was about to cause havoc in the engine, the engine failed fairly spectacularly a wee while later.
Personally I don't agree with your interpretation of the Boeing philosophy regarding making checklist items optional unless there are extenuating circumstances.
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Not only a gate return, but an aborted takeoff as well. More than enough for me not to move a finger until mx looks at the aircraft.
Slot improved shorty after, so we completed our checklists and were getting ready for a new startup. We started engine number 2 and it was a good start. Planning for single engine taxi, we were about to do the "one engine taxi checklist" when we noticed OVHT/DET on the master caution panel.
Looking down on the fire panel, the ENG 2 OVERHEAT was illuminated. We did the memory items. QRH refers you to go to the "engine fire" NNC since the overheat indication still was illuminated, but since we were on stand and already at idle thrust, we put the engine start lever to cutoff instead.
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This would cover you in case someone wanted to hang you out to dry and this does happen
I take it you had Engineer support at the aircraft to diagnose the DRIVE fault?
Having, several years ago, an ENGINE OVERHEAT at approx 200 feet in the air, with a new pilot, I ended up with an almost Single Pilot Operation with added interference (but then I am an old crusty). I would have definitely grounded this aircraft until Engineers had had a good look inside the engine.
B Loop O/heat
I was once called to an aircraft that had a single loop engine o/heat indication, only to discover one of the welds locating a thermocouple housing had failed and the thermocouple had been blown out, leaving a 2” diameter hole in the casing. The other loop was not indicating an overheat, despite the amount of hot gas that must have been escaping with the engine running.
To have suffered an Elect - Drive and an Overheat warning on the same engine and not request mx to take a look - I find surprising.
To have suffered an Elect - Drive and an Overheat warning on the same engine and not request mx to take a look - I find surprising.
It’s been a long time since I flew the 737 but distant memory says that if you have an overheat that doesn’t go away at idle, you are directed to the Engine Fire Checklist, which treats a fire and an overheat as the same thing. In this particular circumstance, following the checklist would lead you to firing both bottles and the overheat/fire still being indicated, so then what? Evacuation? The OP said on stand but was that with a door open or not? At this point I suspect many of us would be looking bemusedly at a shut down engine that has no physical signs of anything untoward going on and and thinking do I really want to carry on down this road?
Yep absolutely right, had too many glasses of wine last night. So I do apologise for the stupid comment.
As far as I can remember the new Engine Fire on the Ground the Memory item is only one bottle to be fired as a memory item.
