N1 - 0, N2 - 0 (737 argument with an instructor)
 

Hello, dear colleagues

Some month ago I had flew with a simulator session on B737CL as a first officer.
Everything went well and at some point I had an Engine Malfunction after V1. Seemed like an engine failure, I reacted very well and kept the aircraft on runway heading. Approaching to 800ft AGL I was told by the first officer that we have an engine failure. But, before making a decision on the actions I need to take, I studied the engine indications. So that is what I am sure of: N1 indicated 0, N2 indicated 0. I have been trained that this indicated an Engine Severe Damage, which made me call for a memory drill of the appropriate checklist.



But after that, I was interrupted by the instructor – stating that he gave me a simple engine failure. My argument about N1 and N2 indications being at point ZERO did not suit him, as it is not stated in any Boeing 737 Manual.

We did not find any agreement at that point. Please guys, any advices on the topic – except for the basic knowledge and some obvious facts.



Best regards!

These are the conditions from the 737 QRH for Severe Damage.

Condition: One or more of these occur:
•Engine fire warning
•Airframe vibrations with abnormal engine indications
•Engine separation.

You had abnormal engine indications but if this was not accompanied by airframe vibrations then it doesn’t meet the condition for Severe Damage. Practically I think this is only possible in a simulator. In the aircraft, the chances of both spools stopped with no airframe vibration is virtually impossible. A signal failure to both indicators may do this but then you may not lose thrust. So, in my opinion, your instructor is technically correct but it’s not a likely scenario for real. Sounds like that sim puts N1 and N2 to zero when Engine Flameout is selected.

If you are at flying speed, the N1 must have some rotation unless it is seized (on the ramp the fan turns in the wind). Different airframe, but still jet technology, Airbus would suggest treating no rotation as damage.

I tend to agree with this. It’d at least be windmilling. The simulator is just that- a simulator. It’s not perfect. Sometimes you just have to nod and smile.

Capt. and Check have said, it'd be pretty much impossible to have zero rotational speed on both rotors without severe engine damage. It could be an indication problem, but there are multiple independent data paths involved for rotor speed that would all have to be failed for that to happen - again, very, very unlikely without severe engine damage (or even separation).

Yes a loss of engine rpm to zero is either loss of signal or locked rotors. Locked rotors are extremely rare. in-flight (too much wind and the broken pieces loosen up) Both rotors being locked in flight is way outside the data base experience but I uppose it could happen

Airframe vibration associated with loss of thrust and any other any engine symptom is time to wake up and follow the FCOM,

The simulators you are typically trained on cannot reliably replicate these combination so a typical training syllabus often simulates something akin to multiple engine symptoms to the point of training you to go deeper into decision making.

Real life events that progress in the powerplant beyond the first seconds following a severe engine failure are indeed rare

IT seems that your simulator is slightly unrealistic and your instructor is not making due allowance for this.
If all rotation came to a sudden stop, some vibration (probably a lot of vibration) would precede it.
Once completely seized, the vibration could then cease.
Further, as it seized there would probably be a spike in EGT.
It is better when in doubt to run the worst case checklist. That is the Severe Damage checklist. The engine is buggered anyway, so what more harm could you do?
Also consider that fire detection and EGT systems are not infallible. You could have a fire or severe over temp which is not obvious. When in doubt do the full drill.
Straight flameouts at takeoff are less likely, and would suggest either a fuel problem (at this stage this would probably be unknown) or environmental (which would be fairly obvious). Healthy engines don’t suddenly stop with no residual rotation.

Had it happen to me...
 

Years ago, during take off right about at V1, had the left engine N2 seize. Thought the left wing was coming off. Whole airplane shook like crazy. First flight of the day; early morning departure. Woke us up for sure.

This was only for a few seconds. Once the N2 was completely stopped, all the violence stopped.

Our SOP at the time was to execute the “Engine Fire, Severe Damage, Separation” checklist. Since we never got an actual fire indication, we stopped the checklist just shy of discharging a fire bottle.

Can’t remember what actual N1 and N2 RPMs are at take off thrust, but it’s a lot. (Maybe 14,500 RPM....dunno?)
For such mass to come to a complete stop in a matter of seconds, it’s a violent experience. I know this; it actually happened to me.

Fly safe,

PantLoad

I’d treat zero N1 and zero N2 as severe damage if there is an associated swing (otherwise it’s a failed indication in my book). And doing the severe damage separation memory items is not unsafe if an engine is failing/ has failed. I am not a TRE or a TRI or a trainer in any respect but I personally think the instructor was wrong to stop the simulator at that point. Have a discussion in the debrief by all means but not during the exercise.

Were you one of two first officers, or in command? Or am I pointing out the obvious?

Airbus says that the following list allows to suspect engine damage :
Rapid increase of EGT above the red line
Important mismatch of the rotor speeds, or no rotation
Significant increase of aircraft vibrations, or buffeting, or both
Hydraulic system loss
Repeated or not controllable engine stalls

The manual states that two or more are required, but in every sim i ever did in an airbus (two different countries, a dozen of instructors from 6 different airlines), no rotation on either N1 or N2 was engine damage.

10 years in CL and we were taught no rotation = severe damage.

To the letter of the law, this ^^^

It’s quite rightly been pointed out that the likelihood of having no airframe vibration if you have both rotors locked is probably nil.

However, you do exactly what it says on the tin (i.e. don’t do severe damage without airframe vibration) and you’ll have something to stand by in court. The correct checklist would obviously be Surge/Limit/Stall which will lead you into a shutdown for this condition anyway. In a real incident, a sneaky lawyer might find some reason to ping the blame on you for a subsequent problem by showing you don’t know the manuals for your engine situation. Anything done outside them must able to be justified in court. Sucks, because I think we all know that two locked rotors must be severe damage. I think in the sim I would let this play and raise it as a talking point. If it was handled safely then the box has been ticked for engine-out handling.

Are we talking a full motion simulator? If it's a fixed simulator, it would be pretty hard to simulate airframe vibration...

What was his point? I don't know the 737, but the only difference is pulling/pushing the fire handle on any Boeing or Airbus I've flown. In the highly unlikely event that you need to restart the thing, it's reversible anyway.

A sim is a good procedure trainer but any instructor or examiner needs to point out that a lot of it is "best guess" anyway. Next time you get a sim TCAS RA, watch what the intruder does. It follows you. Would that happen in the real world?

I am currently working as a 737 Sim Instructor. We teach no rotation equals severe damage. On the instructors panel, selecting this function simulates no N1 and no N2 with no vibration. The only difference to a straight failure being a distinct 'pop' during the actual failure itself. If the candidates treat it as a simple failure to be tackled at the end of the fourth segment, it programs a fire before they reach this point. The Civil Aviation authority we work under treat no rotation as severe damage and expect shutdown in the second segment.

I have had a failure of this nature in real life, although it was a JT8D. It sounded like a bucket of bolts spinning around with initial vibration but once it seized, no vibration at all. There are limitations to even modern simulators and despite the, 'Just like the real thing' sing song they are not and never will be.

Possible cause:

The instructor actioned a simple failure on his controls - and thus were right, while at the same time
The student saw N1 = 0 and evaluated severe damage - which is what needs to be done on the real aircraft.

I’m posting from a decaying memory here (and I know someone will correct me if wrong!) but I recall that there is a difference with approach/attitude from the airframe manufacturers (and hence data providers and these days often the source of the software model) with issues such as “Severe Engine Malfunctions” and “Engine response to Volcanic Ash encounters”.

Whilst Airbus and others suppliers support these types of malfunctions with vibrations, sometimes quite severe or erratic engine indications and or shutdowns being experienced, Boeing tends to take a different approach and has stated that there is no or insufficient data for them to provide the model.

The TDMs of course are obligated to only meet approved data.

In fact what I wrote is a bit confusing. We were 2 first officers training in one session.

In the simulator I operate (B737-300 Category D Full Flight), a flame out initiated on the instructor panel gives instant loss of thrust and a yaw and roll in the direction of the "dead" engine. The N1 and N2 decay until eventually the N2 and N1 show low numbers but continue to rotate slowly under influence of forward speed. There is no vibration. The follow up checklists do not require the crew to pull the fire handles.
There is an item on the instructor panel annotated "Engine Seizure." When actuated, there is instant loud engine noise associated with the engine running down and seizing. At the same time there is the expected yaw and roll towards the seized engine. There is severe vibration which is absolutly unmistakeable physically as well showing up on the relevant vibration indicator. .

In this simulator the N1 will quickly fall to zero caused by the failure of the drive shaft from the accessories gear box, while the N2 will run down more slowly. It is the zero reading on the N1 that is a characteristic of a seized rotor. That, and the severe vibration on that engine that would trigger the Severe Damage checklist rather than a mere engine flameout checklist.

Be careful here if the vibration indicators are EFIS type and not analogue. The needle on the EFIS dial is very small. Beyond a certain vibration limit that needle vanishes off screen. I believe that was one of the problems associated with the Boeing 737-400 crash at East Midlands where mis-identification of the failed engine occurred. In this event the EFIS vibration indicator needle disappeared off screen because it had registered a high reading beyond the capability of the vibration system and thus showed no reading at all on the gauge. It is wise therefore to look for corroborative evidence of severe damage or otherwise rather than rely solely on one source of information

See: https://en.wikipedia.org/wiki/Kegworth_air_disaster

One extract from that report stated:"The vibration indicators were smaller than on the previous versions of the 737 in which the pilots had the majority of their experience. The dials on the two vibration gauges (one for each engine) were small and the LED needle went around the outside of the dial as opposed to the inside of the dial as in the previous 737 series aircraft. The pilots had received no simulator training on the new model, as no simulator for the 737-400 existed in the UK at that time. At the time, vibration indicators were known for being unreliable[3]:69–70 (and normally ignored by pilots), but unknown to the pilots, this was one of the first aircraft to have a very accurate vibration readout."

Post No 2 says it all. If your simulator has the N1 and N2 gauges falling to zero readings simultaneously when on the instructor panel the instructor has selected a simple flameout engine failure, this would suggest the simulator fidelity fails to meet that of a Level D category full flight simulator. Your instructor should be aware of this. If your simulator is a no motion operation then there will be no vibration present. This should have been briefed by the instructor concerned.

Be aware that pedantic simulator instructors exist and you could court retribution if you attempt to argue with these type of characters. A fact of life in simulator training. The QRH/FCOM are your friends when it comes to differences of technical opinion.

And the QRH/FCOM does say that severe damage is Abnormal Indications WITH <airframe> vibration. So hard to argue with that call.

As usual in aviation though, we tend to miss the big picture. It’s obvious the correct QRH will lead into an engine shutdown anyway. So the goal of safely handling an engine failure will be achieved. Providing you didn’t flip the plane upside down of course.

No N1 or N2 rotation is damage, period. If it's a "simple" flame out N1 would be still spinning.

I think in these kind of situations, you just have to nod, pretend to write something down, then do your own research later.

A simple risk/benefit analysis of pulling the fire handle (or not) with a possibly severely damaged engine and accessories tends to lean towards doing it. If it isn’t shot to bits and some time later you really need it back, the procedure is completely reversible. On the other hand, if it is badly broken and still connected to hydraulics, fuel, pneumatics and electrics, there is a chance this may lead to further significant problems, like loss of hydraulic systems, smoke/fumes in the air con or even fire in the nacelle (or a combination of these). Which would you rather be dealing with while flying around on one engine?

Another point is that with increasing severity, there is also an increasing likelihood of high energy bits taking out some/all of the warning systems. A while ago one of our jets had an uncontained failure (on the ground, luckily) which punched holes in the aircraft and set it on fire but there weren’t any immediate warnings...

"Oh I see Captain, thank you Captain. Very useful input. I'll look into that."

This, with a very refined OIC technique, is the best advice.

If that happens, the instructor needs to be taken out training and be retrained or do something else.

You must NEVER leave a training session with question marks popping over your head unless there are some evident contradictions within the documentation or some wording is poorly chosen by the manufacturer/operator. In that case the instructor MUST come back at the earliest stage with an answer to the trainees after consultation with technical pilot or CFI, HT, or anybody who can answer the question.

Worst thing to see in training is people getting out of sim sessions with uncertainties and the inability of the instructor to clearly explain WHY something works the way it does.

I understand that but at the end of the day, most people are trying to get signed up for another six months with the minimum of drama and an extended argumentative debrief is probably not high on their wish-list. There are normally friendly trainers or Standards pilots who can explain/educate in a non-jeopardy environment, plus provide appropriate feedback if necessary.

After 4hrs inside an unreliable box on legs, it’s the last thing you need. I agree about leaving unsure but as long as you clear it up before you go flying again, confidence can return...

You are absolutely right. The problem lies always within the organization and not the trainees in this kind of context.
There are unfortunately too many instructors and examiners in the wrong position and often this has nothing to do with their knowledge or skills, it has to do with the attitude or their ability to be good "educators".

This event is an example of a hazard of misapplication - misunderstanding the concept of SOPs; an extreme SOP culture where all events are expected to follow the rules. Life is far from that perfection; training should concentrate more on process, understanding, thinking about an appropriate course of action, opposed to placing events into neat training boxes to be ticked off.

Also a reminder of how the industry forgets, mislays knowledge, most of which applies today but is put aside because of rarity of events; a weakness from improving safety standards.

From many years ago, and dusted off in the 90s for the PSM+ICR studies, a long lost example of Engine Malfunction Analysis - for crew.
https://www.dropbox.com/s/f18gotbmjs...lysis.pdf?dl=0

PSM+ICR page 2 https://www.skybrary.aero/bookshelf/books/1623.pdf
'The simulator propulsion system malfunction models in many cases are inaccurate and/or do not have key cues of vibration and/or noise. There is also no robust process that ensures the quality and realism of simulator propulsion system malfunction models or that the malfunctions which are used in the training process are those most frequently encountered in service or those most commonly leading to inappropriate crew response. This shortfall leads, in some cases, to negative training.

While current training programs concentrate appropriately on pilot handling of engine failure (single engine loss of thrust and resulting thrust asymmetry) at the most critical point in flight, they do not address the malfunction characteristics (auditory and vibratory cues) most likely to result in inappropriate response.

The changing pilot population, coupled with reduced exposure to in-service events from increased propulsion system reliability, is resulting in large numbers of flight crews who have little or no prior experience with actual propulsion system failures.'

Absolutely Alf.

I remember when I converted onto the 737-200 (wow!) back in the mists of time, when combative Instrument Ratings were a thing, it was almost expected that you’d have run the drills before the gear had fully locked up. Okay, a little bit in jest but not much. No time for analysis, mutual decision making, flightpath assured and all that modern rubbish!

This perpetuated the slavish following of SOPs, IMO, as that was the way to impress the instructor. Watch those hands dance over the levers! See how quick and confident I am! Luckily, being an average kind of pilot, I managed to survive without too much mental trauma but some were not so lucky.

I recall doing a 2-day sim with a captain I’d flown with before on the line - really nice chap and competent operator; not a “rules” guy at all. One of items was a “LOFT” exercise, run by the co-pilot in real time, with various scenarios for the instructor to choose from: due to lack of time, we got a confirmed bomb threat. OK, said I, there’s a familiar airfield right in front of us on a ~3deg approach, let’s go for it at Vmo and do as much of the QRH as we can on the way in. I found the capt. somewhat evasive and continually trying to slow down (not a bad thing in itself) but also determined to do all the checklists right to the bitter end, even if it meant going into the hold. I managed to persuade him that time was of the essence (tick tock tick tock) and through constant intervention managed to get the aircraft on the ground and everyone off pretty swiftly.

In the debrief afterwards, the trainer asked the capt. if he thought I was pushing a bit hard during the approach, and he replied that no, he’d have done exactly the same thing IN REAL LIFE. Unsurprisingly, the rather observant trainer caught that one immediately and asked why it should be any different to the sim? The capt. then described how as a junior F/O many years ago he’d been shouted at by a trainer and told that he would never get a command and shouldn’t be flying at all. His crime? Missing one item off an unimportant checklist. Since then he’d had a pathological fear of simulators, to the point where he had difficulty sleeping during the week before and was physically sick in the car park before each session. He could only survive by doing what was printed on the checklists: no more, no less. He then broke down in tears.

The trainer and I both looked at each other and mouthed a silent “F...”.

Nowadays we’re all nice people(?) and there are peer support groups, industrial psychologists, free mental health care, etc. Back then? Not so much and the expectation was more biased to “man up and deal with it”. Still makes my blood boil how some people were permanently scarred by completely avoidable incidents.

To Fullwings:
 

So beautifully said!


Fly safe,

PantLoad

Ive experienced the very same thing once. Made me Pass my check only partially. Really annoying...

Great story, thanks for sharing ! That is a perfect example of how bad trainers can affect people’s professional activity and life in general.

FullWings :ok:
Instructors and management should read the section on continuous learning; page 4….
RPET The Resilient Performance Enhancement Toolkit 1. Erik Hollnagel, PDF Free Download

Related:- 'Deviant airline pilots: why we need them'.
https://jeroenwolbers.files.wordpres...ine-pilots.pdf

Check the instructor
 

Has any one experienced the C of G being moved during a SIM detail or having it put so far aft as to make the 'a/c' virtually unflyable?

I've witnessed this and had it done to me and wonder if it's possible to have a digital record of key parameters throughout the detail to discourage trainers from playing tricks.........they're NOT all saints :)

As a Flight Engineer for many years with over 11000 hours and many sim sessions I have seen a lot of engine problems, and N1 - 0, N2 - 0, is a engine severe damage / separation checklist, your instructor is wrong!

A tip I give people for the sim in case this should occur, (Engine failure, no vibration, all spools stopped):

If you’ve done the Severe Damage memory actions and the sim instructor questions it, tell them you felt airframe vibration. It’s impossible for the instructor to prove that you didn’t (especially if the other pilot backs you up) and you’ve then met the conditions for Severe Damage. It should then turn into a discussion if the instructor feels like pushing it.

As I said earlier, this situation is a sim only gamesmanship issue. In the real jet, if both spools suddenly stopped there would most definitely be vibration. Severe Damage would be the correct and obvious action.

It's been a while, but in the airlines i flew the 737 every engine failure after take off (V1 cuts) was treated as severe damage, and the engine fire or severe damage or separation checklist was done (call: Engine fire, take action). Yes, for a simple flame out as well. Made things a lot easier as there was no differentiation, just one set of memory items and checklist to do. In cruise that would have been handled differently though.

And yes, no N1 and/or N2 was always seen as sign for severe damage. The newer level D sims had actually very noticeable airframe shudder for a seizure, you would notice that immediately.

We really have some problems these, days, abysmal instructors, seriously lacking in basic airmanship. Zero N1 and N2 tells me the engine is knackered, period.
The Boeing checklist is called for, “ engine fire, severe damage or seperation. “
Carry out the drill and do an engine out approach, not least because no N1 , N2 suggests to me the engine is not producing thrust, if, infact, its still on the wing!

Trying to second guess the cause of the problem is counterproductive. Assume the engine is dead and concentrate on the single engine procedure.

Simples.

Put the jet safely on the ground and THEN make further detailed analysis of the engine problem.
, so perhaps you should ask your instructor exactly what he meant by “engine failure”,

The 737 flies perfectly well on one.

( and yes I was a trainer, trained by Boeing on the 73 with 8000 hours on the type)

:ok: Ex 73 - absolutely agree.