View Full Version : Engine failure/Fuel leak 737

fastidious bob
23rd Jan 2008, 10:44
I was speaking to a colleague the other day who had just been in the sim. He had an engine flame out just after take off. He identified the problem as a fuel leak. He then carried out the engine fuel leak checklist. Much to his surprise in the debrief the TRE said he should have carried out the engine failure/shut down checklist first and then carry out the engine fuel leak checklist. My colleague argued that the two checklists are effectively the same. Any thoughts?

23rd Jan 2008, 10:54
The TRE was right,you have an engine flame out,you do the failure/shutdown checklist first and then the fuel lick.Its approximately the same i agree but this doesnt mean anything in particular

23rd Jan 2008, 10:57
Prioritise the failures. An engine failure is not a fuel leak.
Although the first may be caused by the second, it may not be the case.
So do the engine failure drill, entirely, then move onto the lower priority fuel leak, entirely. Once all that has been accomplished then go back to a possible relight, once the configuration etc has been analysed.
TRE definitely correct on this one.

fastidious bob
23rd Jan 2008, 11:09
But why do the same checklist twice? The engine failure is a secondary effect to a primary cause, the engine fuel leak. Also engine failure/shut down check list tells you to balance the fuel, would you follow this as well? And as for a possible relight? I would not even consider this if I had any engine failure (except if performance was compromised), and I definitely would not relight with a fuel leak.

23rd Jan 2008, 11:26
By safeguarding the engine first you remove any source of spark/flame etc that could develope into an engine fire. The airflow around the engine will see that the fuel is dispersed behind the aircraft. Once you secure the engine then deal with the fuel. Also this theory goes back to propellor aircraft, you need to secure the engine/prop first to reduce drag then deal with the fuel problem.

23rd Jan 2008, 11:37
How was your colleague able to deduce that it was a fuel leak that caused the flame out? Was there a significant fuel flow indication on the fuel flow gauges after the fact that the engine had flamed out?

Interesting scenario as the fuel flow transmitters are DOWNSTREAM of the MEC (Main Engine Control) (B737 Classic) or the HMU (Hydro Mechanical Unit) (B737 NG).

In this case isn't the throttle system smart enough to stop the flow before it reaches the Fuel Flow Sensors ie stop the flow at the MEC/HMU?

I notice the Fuel Leak checklist confirms the leak by firstly turning off the centre tank fuel pumps observing an imbalance between the two main tanks. How long is that going to take? (rhetorical question)

Either checklist (Engine Failure or Fuel Leak) would secure the situation when the Start Levers are moved to cutoff (this closes two valves that cuts off the fuel upstream and down stream of the MEC/HMU). I suspect you would get to that stage in the checklist quicker if you were to do the Engine Failure checklist.

While I initially thought your colleague had a valid argument, points already made here by other posters are pretty compelling.

fastidious bob
23rd Jan 2008, 12:57
kwachon (http://www.pprune.org/forums/member.php?u=137540)

You are safegaurding the engine by carrying out the fuel leak checklist.

františek dobrota
23rd Jan 2008, 18:38
:=FYI 737CL:
http://www.ukazto.com/img_small/2001005,ff.bmp.jpg (http://www.ukazto.com/?img=2001005,ff.bmp.jpg)

23rd Jan 2008, 19:20
Yes. Thank you františek dobrota. I've corrected my post. I know what I meant to say, but I somehow said the opposite. Sorry. :)

23rd Jan 2008, 19:27
fastidious bob,

You have no way of knowing where the fuel leak is, by shutting down the engine, i.e going into cut-off, you remove the spark and stop further fuel into the hot section, now deal with the fuel leak if there still is one.

fastidious bob
23rd Jan 2008, 20:31

I think you are missing my point. The fuel leak checklist on the 737 instructs you to shut down the engine!

Port Strobe
24th Jan 2008, 00:40
Forgive my ignorance but may I ask if the engine flamed out on departure, in the absence of visual indications of a fuel leak from adjacent windows in the cabin or perhaps smelling the vapour then how does one diagnose this as the cause of the failure? I imagine after departure the crew follows the OEI profile then when they look at the fuel distribution after cleaning up it would probably be greater on the side of the failed engine since the good one has probably consumed c250kg in 5 mins taken to complete this, assuming a minimal imbalance prior to departure. Are you then looking for a decreasing quantity or a positive fuel flow indication on the failed side to show there is a "demand" for fuel with the engine failed but the valves still open due to the start lever being in the idle detent?

24th Jan 2008, 05:50
fastidious bob,
My personal opinion (which amounts to nothing in the real world), is that I would control the engine failure. That is the primary risk to flight safety. A new question for you. Was your friend part of a structured sim program, or was it a random failure. I only ask as at my previous company, there was plenty of info around as to the sim profile for various checks. Could your friend pre-empted the fault due to others info?

24th Jan 2008, 06:10

I have 5000hrs on type as a commander,I can tell you that your friend is not only wrong,he is dangerous as well!

Engine failure 'just' after take off has alot to think about.You must 1st secure the engine so it wont give you further problem.Fly a proper departure,be it a SID,EOSID,vectors,proceed to holding waypoint etc.Then take time to analyse the engine.Don't forget you can be as much as 8tons(-400) over your max landing weight! Why rush to come back for a single engine landing if you could have normal 2 engines landing if you can get the other engine to start? (go have a good look at the engine out flap 15 landing distance/speed at max takeoff weight). Engine fuel leak has a limited rate.If a tank went zero just after take off with engine out due fuel exhaustion,it may well be a tank leak rather than an engine fuel leak,there isn't a checklist for tank leak.(happened to me once on a long flight over water).As long as you have enough fuel to come back,the rest of the fuel leak away can reduce the a/c landing weight/speed.Also,since the engine fuel leak has a limited rate,it is always important to analyse carefully,don't jump the gun.