Boeing Engine Failure or Shutdown NNC

[Speedbird744]

In the Engine Failure or Shutdown NNC, specifically for the B737, it states "Do an engine shutdown only when flight conditions allow".
Does anyone have an idea what those conditions are? When would we stop at that point and say we should delay shutting the engine down?
Please provide any input you have,

Many thanks..

[vapilot2004]

When would we stop at that point and say we should delay shutting the engine down?

An obvious example would be shortly after takeoff, naturally, even in the case of engine fire. Generally, the consideration is "continued safe flight", which goes to the ANC principal.

[wiggy]

An obvious example would be shortly after takeoff,

Agreed.

For example if you get a straight forward engine run down with an associated ENG FAIL Eicas msg just after takeoff, you wouldn't be expected to start actioning the engine fail check list until you'd "cleaned up" the aircraft.

[Speedbird744]

Understood however we wouldn't even go to the NNC for engine failure until the flaps are retracted and everything is under control. This is for the B737, I should imagine it's the same with other Boeing models. So clearly it can't be to do with that....

[JammedStab]

Probably, the conditions are intentionally not identified by Boeing for their own protection from inevitable lawsuits which happen all the time even though the crew made the obvious error, not the manufacturer. I'm sure the conditions could range from terrain clearance requirements to how busy the flight crew are.

[RAT 5]

I would hazard a guess of an engine mis-behaving but not a failure or worse, and not a simple case of when a parameter reaches a limit and is covered by QRH. This could include oil issues, VIB's of uncertain nature, mysterious noises but not a certain surge/stall. I think they've left it open for pilot discretion.
It is an educational scenario in the sim to give a failure that results in ending up with an engine running at idle or much reduced thrust and watch what the crew decides to do about it. This is not a simple basic QRH scenario and requires good decision making and crew coordination.

[FullWings]

Taking the simple view, the intent is probably to try and avoid shutting down an engine (which is often not time critical but very critical on getting it right) during a period of peak workload and essential monitoring, like an emergency turn and/or terrain constrained departure. It also helps the aforementioned turn/departure go according to plan as well.

If you were operating at optimum+ altitudes in the cruise, it might be sensible to sort out where the aeroplane is pointing before securing the engine as doing it the other way round (or attempting both at the same time) could cause problems.

I have seen the phrase “...only when a safe flightpath is assured” mentioned in quite a few manuals when describing some non-normal procedures. I think that is generally sage advice...

[RAT 5]

Lets be sure and differentiate between an engine failure and a shutdown. The former it has stopped producing thrust and the latter is a manual shutdown after which it will stop producing thrust.
Talks of emergency turns etc. is most likely after a failure. Sadly, the tick-box sim sessions always include the former and very very rarely the latter. In the real world I hazard the guess that the latter might occur more often than the former. As mentioned it is also a sound education exercise to insert a failure that allows the engine to run at idle and see what the crew do for approach.

[zlin77]

Only when flight conditions allow...

As far as I am aware, the Boeing intent is to have the A/C under control and above 400'AGL before proceeding with memory/recall items, the primary task is AVIATE, which means don't introduce anything else into the scenario at this stage, remember all QRH Items are constructed by engineers/pilots then vetted by LAWYERS who will determine that the procedure will not leave the company open to litigation if things go tits up!!

[APU_inop]

The engine doesn't only produce thrust, it is also used for pneumatical and electrical supply. If you dispatch the airplane with a problem with one of those, you might sometimes be better off leaving the engine running until sorting out a plan B.

[tdracer]

Most engine failures are not time critical - you want to take the time to make sure you're doing the right thing. For example, it's been known to happen that the crew shuts down the wrong engine (it's even happened during a Boeing 757 flight test - I had a good buddy on board who commented that "it got a little tense" - fortunately they were at ~30k and had time to recover).
Read the those instructions as 'take your time and get it right'.

[RAT 5]

It's interesting. I sense you responses are driven by the dull unimaginative repetitive sim engine failures. That's not the real world.
You're correct about ancillary systems. I know of one captain who 'nursed' a B767 home over a CAVOK Europe with 1 engine and reduced power. It was an ETOPS a/c within 2 hours of base and his defence was he hadn't shut down the other one; etc' etc. He was a very company man, got away wth it and no more was heard. I'm not wanting to open a whole new discussion about the right/wrong; just that the sim sessions are not so realistic.

[lomapaseo]

It's interesting. I sense you responses are driven by the dull unimaginative repetitive sim engine failures. That's not the real world.
You're correct about ancillary systems. I know of one captain who 'nursed' a B767 home over a CAVOK Europe with 1 engine and reduced power. It was an ETOPS a/c within 2 hours of base and his defence was he hadn't shut down the other one; etc' etc. He was a very company man, got away wth it and no more was heard. I'm not wanting to open a whole new discussion about the right/wrong; just that the sim sessions are not so realistic.

Sim failures can not possibly cover all probable engine failures, both from time in session as well as practical limits of the simulation modes. But that is a broad subject.

On the other hand there is now a large amount of engine failure data that confirms the ability for the engine to continue to run stably with enough power for pumps and generators and in many cases to be able to be returned to some limited power.

As always follow your training unless that won't work and you're out of viable options