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-   -   N1 - 0, N2 - 0 (737 argument with an instructor) (https://www.pprune.org/tech-log/636836-n1-0-n2-0-737-argument-instructor.html)

Mach E Avelli 22nd Nov 2020 01:23


Originally Posted by FullWings (Post 10931517)
And that is the nub of it and why this thread exists at all.

There is a tendency to drift towards the unquestioning following of SOPs and that there is only one way (my way) of dealing with an issue that gives a positive outcome. There are very, very few circumstances that require immediate action with no real time to think about it first (high-speed RTO comes to mind). Although an engine failure seems like a simple thing with clearly defined actions as a result, even this is not as straightforward as it seems.

One of our training documents is a 40-page interactive book covering some of the engine failure possibilities and ways to deal with them. OK, you say, but to keep things simple, the manufacturers have distilled all that into a few choices that are simple to action in a time of high workload. Absolutely true, I say, but you can still end up in a cul-de-sac if you rush in blindly without due mental process. Imagine you go through a flock of birds after takeoff (does happen) and there are a few pops but the engines are still running. Shortly after that you notice the EGTs are high on both and then there is a fire warning on one engine. SOPs say to shut it down and fire the bottle but is that wise *right now*, especially as it is still producing thrust? What are we going to do if we get a fire warning on the remaining engine?

I’m sure everyone reading this would pause and reassess the situation, should it happen to them, but if you continually beat people over the head to follow SOPs no matter of any indication to the contrary, it might lead to a sub-optimal outcome. The fate of the French Concorde was sealed when a running engine was shut down due to a fire warning, leaving not enough thrust to stay airborne. Yes, it was probably going to crash anyway but that action made it a certainty.

Fullwings you speak my language!
At the risk of thread drift, there is a problem arising in some training 'cultures' which I think stems from being too anxious to pitch every procedure at some primitive pilot (the lowest common denominator) who has somehow infiltrated the system and is waiting to screw up.
We see policies written that forbid pilots to ever reset a circuit breaker unless it is specifically called up in the QRH. No more making one reset if you would like to have the system, but instead write it up for the engineers to reset and too bad if you are at a non-engineering port. No more attempting one recycle of some 'sticky' valve - write it up and ground the operation pending an engineer hitting it with a rubber hammer.
As for running an engine beyond its 5 minute limit if it's really needed to ensure adequate performance, or making a spit-arse turn to a reciprocal runway and landing overweight with an uncontained fire and not completing the full checklist - heaven forbid it should ever be suggested, let alone practiced in the simulator.

The result of this mentality is we have carefully scripted simulator checks where everything is rehearsed well before the event. I have actually had candidates ask me for the exact test sequences, approaches, route etc 14 days in advance of a simple Instrument Rating renewal. They arc up when I reply with a copy of the official test form and delay notification of the route until 24 hours in advance. Yet their masters often hit them with short notice roster changes or off-schedule charters and they cash their pay cheques cheerfully enough.
In some jurisdictions it seems gone are the days of non-jeopardy LOFT exercises where crews were encouraged to step outside their comfort zone. Now, it's all about ticking the boxes on the form.

Centaurus 22nd Nov 2020 03:46


The result of this mentality is we have carefully scripted simulator checks where everything is rehearsed well before the event
It may be an Australian thing to cover once's backside in event a CASA audit.

In another era I did some contract simulator training on the 737NG with the then SAS Flight Academy at Arlanda airport in Sweden. Instructors were encouraged to use their experience within reason and time permitting to add the occasional non-jeopardy exercise. By chance I was training two experienced former Israeli pilots for their type rating on the 737NG. Both were 747 captains who had bid down to fly the new 737NG rather than spend a life in long haul.

Both had flown Mirage fighter bombers on war operations with the Israeli Air Force. They certainly knew how to fly. Midway through the type rating we were ahead of schedule and I asked if they would like to practice a tight low level circuit to see how quickly they could get on the ground given a terrorist event on board. After all, these threats were not unknown in their part of the world.

From lift-off, into a close-in circuit to stopping after touchdown, started with five minutes. With further practice both pilots were able to takeoff and land the 737 in under two minutes from lift off. Under these emergency conditions there was no time for checklists or the niceties of TEM and CRM. They both flew superbly and were so impressed with this exercise and its applicability to a war zone operation, their airline El Al Israeli Airline introduced this low level tight circuit into the training syllabus. .


FullWings 22nd Nov 2020 10:22


Originally Posted by Mach E Avelli (Post 10931927)
The result of this mentality is we have carefully scripted simulator checks where everything is rehearsed well before the event. I have actually had candidates ask me for the exact test sequences, approaches, route etc 14 days in advance of a simple Instrument Rating renewal. They arc up when I reply with a copy of the official test form and delay notification of the route until 24 hours in advance. Yet their masters often hit them with short notice roster changes or off-schedule charters and they cash their pay cheques cheerfully enough.
In some jurisdictions it seems gone are the days of non-jeopardy LOFT exercises where crews were encouraged to step outside their comfort zone. Now, it's all about ticking the boxes on the form.

We have gone down the ATQP route and almost everyone I speak with much prefers it. In the old days you almost had to get hold of the instructor's notes as it was assumed that you were in possession of them anyway! IMO it led to a rather false atmosphere with crews sitting there waiting for the EVENT then responding far too quickly with a pre-prepared plan.

Now, the trainer (within practical limits of time, databases, etc.) can let the detail progress according to the decisions made by the crew and can alter things as it is no longer running on rails. The focus has changed from being +/- X kts and +/- Y ft to “how was the situation managed?”, “did they use all the available information to come to a decision?”, “was the decision making process effective?” and things of that nature.

Of course we still do traditional failures, malfunctions, handling, etc. but that’s more “train to competence” so on a assessment detail the soft skills are much more under the microscope, as they have greater influence on bringing a flight to a successful conclusion than being able to do an inverted night asymmetric NDB on a partial panel...

Check Airman 22nd Nov 2020 20:42


Originally Posted by Mach E Avelli (Post 10931927)
As for running an engine beyond its 5 minute limit if it's really needed to ensure adequate performance, or making a spit-arse turn to a reciprocal runway and landing overweight with an uncontained fire and not completing the full checklist - heaven forbid it should ever be suggested, let alone practiced in the simulator.

Funny you should mention this. I recently did engine out training event where I opted to ignore our non-normal SOP for power and flap settings in light of the high terrain and elevation. The instructor had no objection to the decision.

There are still good instructors out there. Ones who can read a checklist, and still remember how to fly an aircraft. Give me one of those guys any day.

lomapaseo 23rd Nov 2020 19:45

I guess somebody has to practice a severe engine ,damage check list of some sort but in all my memory I can't think of one event where both rotors seized or even where a non fire shutdown without A/C vibes saved the day.

Way too many old wives tales about "why" relative to loss of n1 and n2 not associated with a departed engine.

Don't get me wrong, I'm all for pilot training about when to fly and when to read a checklist but let's not outthink the causal details.

Checkboard 24th Nov 2020 14:38


in which case that is major damage or the engine has departed the aircraft completely
If the engine has departed the airframe, the LAST thing you will notice would be the N2 indication. :)

I've flown a separation in the sim a few times - it's an interesting exercise as the loss of weight on one side means you are applying opposite airleron to rudder. Of course - that's the sim. In the real world the engine tends to depart under thrust - so goes forward, then up and over - in the process taking the leading edge dvices with it so you lose weight, but also lift....

lomapaseo 24th Nov 2020 18:42


Originally Posted by Checkboard (Post 10933802)
If the engine has departed the airframe, the LAST thing you will notice would be the N2 indication. :)

I've flown a separation in the sim a few times - it's an interesting exercise as the loss of weight on one side means you are applying opposite airleron to rudder. Of course - that's the sim. In the real world the engine tends to depart under thrust - so goes forward, then up and over - in the process taking the leading edge dvices with it so you lose weight, but also lift....


Don't forget it also goes 90 degrees to the right or left depending on which way the rotors are turning.

megan 25th Nov 2020 01:55


in the process taking the leading edge dvices with it so you lose weight, but also lift
The trouble with the DC-10 at Chicago was that it relied on hydraulic pressure to keep the leading edge devices deployed, once the hydraulics lost pressure due damage incurred they retracted. It was said it wouldn't happen on a Boeing as the devices are mechanically latched (I don't know if that is indeed a fact, but was a reason given at the time). If that is indeed the case I'd assume damage would be limited to those devices impacted by debris and the loss of lift being minimal.

tdracer 25th Nov 2020 02:18


Originally Posted by megan (Post 10934134)
The trouble with the DC-10 at Chicago was that it relied on hydraulic pressure to keep the leading edge devices deployed, once the hydraulics lost pressure due damage incurred they retracted. It was said it wouldn't happen on a Boeing as the devices are mechanically latched (I don't know if that is indeed a fact, but was a reason given at the time). If that is indeed the case I'd assume damage would be limited to those devices impacted by debris and the loss of lift being minimal.

That's correct, although not via mechanical latches. On Puget Sound Boeings, the flaps/slats are moved via jack screws - not by direct hydraulic pressure as was the case on the DC-10. Jack screws can't really be back-driven, so loss of hydraulics means they'll stay where they are.

lomapaseo 25th Nov 2020 13:03


Originally Posted by megan (Post 10934134)
The trouble with the DC-10 at Chicago was that it relied on hydraulic pressure to keep the leading edge devices deployed, once the hydraulics lost pressure due damage incurred they retracted. It was said it wouldn't happen on a Boeing as the devices are mechanically latched (I don't know if that is indeed a fact, but was a reason given at the time). If that is indeed the case I'd assume damage would be limited to those devices impacted by debris and the loss of lift being minimal.

Don't forget that it's not just loss of lift but roll recovery as well. Some planes can be managed well at speed, but when you slow down to land you have got your hands full.

Centaurus 26th Nov 2020 00:05


In the real world the engine tends to depart under thrust - so goes forward, then up and over - in the process taking the leading edge dvices with it so you lose weight, but also lift....


https://en.wikipedia.org/wiki/Americ...nes_Flight_191


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