View Full Version : Engine Failure (Run down) 738

Pin Head
27th May 2015, 06:55

Just gauging thoughts on an Engine Failure, no ENG FAIL annunciation, so just run down.

Pros and cons of following QRH and going to secure engine and shut it down.

It was a non etops sim exercise with a serviceable APU.

27th May 2015, 07:48
If no "eng fail" amber on N1 gauge are you suggesting a 'Low Idle' condition? What did the other parameters read? If you shut it down with no apparent damage you could attempt a restart. What did you do?

27th May 2015, 18:49
How is the engine going to " run down" below sustainable idle without any " fail" indication?

An engine failure alert indication (ENG FAIL) is displayed in amber on the EGT indicator when the respective engine is operating at a condition below sustainable idle (50% N2) and the engine start lever is in the IDLE position. The alert remains until the engine recovers, the engine start lever is moved to CUTOFF, or the engine fire warning switch is pulled.

28th May 2015, 13:08
Failure of the ENG FAIL annunciation

I am sure it can happen given all other oddities seen

28th May 2015, 19:28
Why should the lack of an "ENG FAIL" annunciation be a problem - do you not still have N1, N2 ,fuel flow, EGT?

Pin Head
28th May 2015, 19:36

Yes it did, just the low oil pressure as expected.

We shut the engine down but thinking about it could you of left it running or am I thinking ETOPS too much (which I used to do on the aircraft).

Shutting an engine down would. Nearly ground an airline if there operation is all EToPs

28th May 2015, 20:09
Very difficult to understand this discussion without knowing Spool RPM, EGT and some other details.

If one were to describe an engine cycle failure than EGT is very important to know. Otherwise I would want to know what's happening to the fuel.

I hate to shutdown an engine that is not real time threat to the aircraft as in the absence of excessive EGT or felt vibration I would take my time in deciding (assuming the fire bells aren't still ringing in my ears)

29th May 2015, 20:29
"If you shut it down with no apparent damage you could attempt a restart."

This sort of advice/practice from trainers worries me.

The only turbofan to quit silently and discreetly with me in 26 years of operating them, did so in the descent, accompanied by the "normal" annunciators indicating lo oil press, hyd & elec services etc.

Approach continued and 'frame given to the engineers for investigation, push off home non the wiser.

It failed because the HP fuel feed to the burner gallery was punctured by a chafing clip and we were lucky it chose to do so spraying fuel onto a relatively cool engine body. Had it occurred in the climb or cruise it probably would have been an engine fire.

Modern turbofans don't normally quit for trivial reasons, and the current training practice of encouraging crews to do a relight in the sim is, IMHO, is of dubious value. If the flame has died due to rain/hail ingestion or silly AoAs during unusual manoeuvring, then maybe a case can be made for a relight, but any donk which quits quietly of its own accord could be as sick as ours was and relighting MAY present a greater hazard. :suspect:

Mach E Avelli
29th May 2015, 23:51
Barking mad, that is exactly what I preach.
Further, I tell them that they should only relight if they REALLY REALLY need to because a greater danger exists if they don't.
The problem with re lights is that damage is sometimes exacerbated. Without a good reason acceptable to the chief pilot, should damage occur during the relight process it will be a large deduction from next month's salary to pay for it.

30th May 2015, 01:25
The data is the key to safety and lessons learned.

There is little data to support the idea that a successful relight will exacerbate damage at flight idle.

Having a second engine running at critical flight regimes for electrical and hydraulic power is lot better than one.

The recommendation by the manufacturers are data based on experience and expertise. Pay attention to these before developing your own ad-hoc syllabus.

I do support the publication of manuals, official instructions on this forum as the lead to what-if questions. I'm not a fan of pilots designing their own without regard to normal sources of help.

Mach E Avelli
30th May 2015, 04:08
Not the 738, but we had a Technical Pilot on staff who did post maintenance test flights. The schedule he had developed called for a shut down and relight. After several cases where damage occurred during the relight process it was decided that this was no longer a good idea.
As Barking mad says, modern turbofan engines don't normally run down. So, unless the emergency dictates a relight, why do it? A modern aircraft has enough redundancy to get you home with one engine inoperative.
Now if the QRH specifically says to attempt a relight - as in a volcanic ash encounter - that is exactly what one should do.
But if the QRH is silent on the subject, leave it be.

30th May 2015, 09:15
Now if the QRH specifically says to attempt a relight - as in a volcanic ash encounter - that is exactly what one should do.
But if the QRH is silent on the subject, leave it be.

There are operators who have tailored the QRH to suit their SOP's; and one such, approved by Boeing, is an simple ENG Failure with no indications of damage WILL be followed by an attempted inflight start. It's a crew decision in standard Boeing; there it is an SOP.

30th May 2015, 10:06
The golden rule should always be " diagnose" then take the appropriate actions but not outside of the manufacturers QRH, which is the most condensed format for addressing non-normals. A " real life" example of crew messing up was last year when on a 738 one VSV sensor failed and allowed the engine to go to ground idle condition at 38000. The result was an " ENG FAIL" amber and the crew actioned the " severe damage" C/L. In fact time spent on diagnosis would have shown N1 and N2, FF, EGT and Oil pressure, a simple advance of the T/L would have removed the warning. The problem in the sim is limited time and crews tend to react in the way they perceive the instructor wishes, on the other hand instructors can often generate " out of the box" scenarios to test the crew. There is a thin line between negative training and practicing situations.

30th May 2015, 13:04
Thats why I believe LOE along with ATQP style of training is more beneficial.

30th May 2015, 18:11
The result was an " ENG FAIL" amber and the crew actioned the " severe damage" C/L. In fact time spent on diagnosis would have shown N1 and N2, FF, EGT and Oil pressure,

I find this astonishing. I've worked for many different airlines and training depts. True, my own technique was ingrained by the first one, and it's attitudes were excellent. I took them with me in my crew bag to airlines whose training dept's were less developed. Indeed, after a couple of years in the training depts some of my techniques quietly found there way into the evolving SOP's. Engine malfunction analysis was one of these techniques. Don't rush, analyse all data and come to a conclusion, with your mate; then action the correct agreed QRH. There was one airline, but more associated with an RTO, that a STOP for engine failure had to be confirmed by 2 parameters one of which could be the swing/yaw. A single instrument indication was not enough. I couldn't get that passed on, but the very common analysis technique did include all the engine gauges. So how could this shutdown action be taken simply by ONLY an ENG FAIL flag?

30th May 2015, 20:14
I cannot see the rationale behind adopting a policy never to attempt a relight based on one solitary occurrence in your dim and distant past where a relight would have had unwanted consequences. Supposing the engine was 100% OK but your last fuel uplift was contaminated? You might think everything is fine on the remaining engine until it too is affected. The more engines running the better for me!

cosmo kramer
30th May 2015, 21:03
Supposing the engine was 100% OK but your last fuel uplift was contaminated?

Contaminated fuel = fuel filter bypass

30th May 2015, 22:03
I was thinking of water contamination at positive temperatures.

Mach E Avelli
30th May 2015, 23:21
Erm.....where in any of the above posts has anyone said to NEVER attempt a relight?

Once, while ferrying an ancient Vickers Viscount, we experienced total fuel contamination in all tanks. The aircraft had been parked in the desert for several years. On the initial test flight with just a small quantity of fuel, it flew OK. But when we filled the tanks, the fuel sloshing around washed a lot of perished rubber at the top of the tanks into the system. One engine auto feathered, followed a few minutes later by its adjacent engine flaming out. The fuel flow meters for the other two were dancing about all over the place. We tried to relight but of course to no avail. Landed at a military aerodrome and spent the next week cleaning all the black gunk out of the fuel system and having the tank bladders recoated.
If fuel contamination is bad enough to stop an engine, it is unlikely to go away for a relight.

cosmo kramer
1st Jun 2015, 10:53
I was thinking of water contamination at positive temperatures.
Are there any incidents in the past to support such a scenario, or is it purely hypothetical?

Modern engines have auto-relight functions. E.g. The CFM56 EEC will switch on both igniters if there is an uncommanded rapid drop in N2. Hence, should the burners be "supplied with water" instead of fuel for a short while (if even possible, but hypothetically speaking), the igniters will be turned on and as soon as the water has passed the fuel should re-ignite, preventing an engine failure. My guess is, that there should be a helluva lot of water in the fuel for the engine to fail outright.

1st Jun 2015, 14:28
Can't recall any to be honest. I still think a relight should be considered on a twin where possible and Boeing agree. I do also see the wisdom of leaving well alone if you can get by with the remaining engine and there is any uncertainty about the integrity of the failed one.