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No N1 and N2 rotation - Appropriate non normal checklist

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No N1 and N2 rotation - Appropriate non normal checklist

Old 29th Nov 2021, 19:20
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No N1 and N2 rotation - Appropriate non normal checklist

Boeing CF6/GenX oriented question -

If you suffer an engine failure and there is 00.0% N1 indication and 00.0% N2 indication (seizure, no windmilling), what is the appropriate non-normal checklist to run? Is it ENG 1 FAIL (as the EICAS would indicate) or should you run the unannunciated "Engine Severe Damage or Separation" checklist? No vibrations or other abnormal indications present. I cannot find this scenario specifically addressed in the FCOMs or flight crew training manuals. Training department teaches to go with the ENG 1 FAIL.
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Old 29th Nov 2021, 19:41
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Sorry, not a Boeing person, but on the A300 with CF6 engines, no N1 and no N2 was considered "Engine Severe Damage or Separation" as you don't know what has happened to the engine.
It may be seized, hanging off the wing, spilling fuel or oil, or it may be just an electrical harness fault.
The old saying, "If in doubt there's no doubt", comes to mind.
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Old 29th Nov 2021, 19:49
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Without reference to any publications and slowly getting drunk in a Thai restaurant I’d say:
Doesn’t ENG FAIL checklist refer to the severe damage checklist through the decision tree?
  • if this go to step 4
  • if this go to other checklist
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Old 29th Nov 2021, 20:04
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No access to the checklists to see what they say, but as an engine specialist:
No N1 indication and no N2 indication would strongly indicate:
a) very severe engine damage
- or -
b) the engine's not there anymore
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Old 29th Nov 2021, 21:24
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Original post said indications of 0% rather than no indications so I would tend towards severe damage rather than missing. Coming at this from a logical point, look at what the differences are between the two checklists?

Eng Fail leaves you in a position to relight, severe damage does not. So I would ask myself "from the observed indications would I try to relight this engine" If the answer is no, then there is no harm in completing the evere damage checklist.
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Old 29th Nov 2021, 21:32
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This thing has been doing the rounds for at least 30 years. What's the actual difference in the drill? Severe damage means you override and pull the fire handle. Which is actually reversible if really needed.

Think about it logically. The chances of both N1 and N2 dropping to zero because of an indication fault are extremely slim. If the engine was in fact operating normally there would be no yaw/roll effects.

I think it is unlikely that a genuine failure that rapidly results in N1 and N2 seizures will leave you in any doubt about whether to apply the failure or damage drill. The associated extra drag, rudder requirement, buffeting etc associated with the indications should all point to applying the severe damage procedure.
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Old 29th Nov 2021, 21:50
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I agree with all of you, which is why it is frustrating to be instructed to run the ENG FAIL checklist in this situation. The ENG FAIL checklist asks you "do high airframe vibrations WITh abnormal engine indications exist?". If yes, then you go to the Engine Severe Damage or Separation checklist.

The problem is, you could, at least in the sim, have 0.00% indications, which yes are abnormal, but no vibration. However, since both conditions in the conditional statement are not satisfied, the "WITH" condition is not satisfied and you remain in the ENG FAIL checklist. I think part of this is driven by the fact that thr company doesn't think crews are capable enough to run the unnanciated electronic checklist for sever damage and then go back and override the ECL for ENG FAIL.
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Old 29th Nov 2021, 23:26
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Rt Hon Jim Hacker MP

In one of my previous airlines (B757/B767 operator) our training was to treat all engine failures on take off as severe damage. With no fire indication the fire switch was pulled but the extinguisher was not discharged. If a relight was subsequently determined to be desirable then the fire switch was simply pushed back in. This allowed the relight envelope to display on EICAS and the only thing that had been lost (in addition to engine thrust from the failed engine) was a associated engine driven hyd pump which had been depressurised and would need resetting after landing.
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Old 30th Nov 2021, 00:59
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The phrasing “Airframe vibration with unusual engine indications” is common between the CF6 and CFM56. The only dramatic jet engine failure I’ve experienced wasn’t a GE engine but a Pratt JT8D and it only had a “Engine Fire/Failure” checklist. The was a little shudder and then a couple minutes later the four and a half bearing failed with a WHOLE lot of shaking. After 5 or 10 seconds when our eyes could focus on the engine gauges there was no rotation in one section, maybe both, I can’t recall. I don’t think you could have an engine seizure without some unusual vibration.
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Old 30th Nov 2021, 06:57
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Originally Posted by ASRAAMTOO View Post
Original post said indications of 0% rather than no indications so I would tend towards severe damage rather than missing. Coming at this from a logical point, look at what the differences are between the two checklists?
It depends on the exact engine/aircraft combination, but even most FADEC engines have a 'backup' analog input for N1 and/or N2. If the engine is physically gone, the analog input will indicate zero, not 'invalid' or a blank display (which loosing the FADEC connection would do). So a 'zero' indication (rather than a blank display) is no assurance that the engine is still there.
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Old 30th Nov 2021, 07:51
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Nothing to see here, fly along now…



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Old 30th Nov 2021, 08:56
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I cannot find this scenario specifically addressed in the FCOMs or flight crew training manuals.”

Its good to ask questions, but don't expect a definitive answer from PPRuNe or anywhere else, because its most unlikely that any ‘solution’ will relate to the actual situation (scenario) that only ‘you’ will encounter.
As previous posts above, heed the advice as to what to look for, check the wider situation, outside of the ‘canned’ instrument displays, consider aspects which cannot be simulated or written in SOPs.

Choice from alternative FCOM procedures must start from understanding the situation - there is no SOP, must do, right or wrong; no specifics for awareness, only judgement. Then choice, act, review, etc
A better question is for advice on assessing likely situations, what could be considered, and how understanding is formed.

Judgement - ‘Airmanship’, no SOP, App, … or on EICAS. Such is the modern world, uncertain; manage it as you see it at the time, because events will not be as imagined as per PPRuNe, simulator training, or as in procedures.
Airmanship: https://www.dropbox.com/s/bhpin7se6m...light.ppt?dl=0

In days past, there was guidance … https://www.dropbox.com/s/gp1e9gvps3...lysis.pdf?dl=0
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Old 30th Nov 2021, 09:56
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Memory items:
  • Is their name on the tail?
  • Is their name on your paycheck?
  • Follow their procedure
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Old 30th Nov 2021, 13:18
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safetypee thanks for the links. It's a reassuring read on the very first text page where
Follow the rules.They are usually right. Understand the rules and the reasons for them. Do not accept that rules will have to be bent to get the work done.
Not so fast.
Think first. Do you really understand the problems. Reject opportunities for shortcuts or to do things that appear to be ‘better’.
It could happen to you.
Carelessness and overconfidence are much more dangerous than the calculated acceptance of risk.
Are explained to be the core material from which the foundation to 'airmanship' is made.

Last edited by FlightDetent; 30th Nov 2021 at 13:30.
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Old 30th Nov 2021, 15:08
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the protection of 2 inch armour plate

FlightDetent,
Unfortunately in modern times we have to consider semantics. ‘Rules are rules’, often associated with legalities, then this view misapplied to all ‘procedures’ without thought and understanding.
Operations must start from an understanding of the situation, check, adjust understanding not procedures; PPRuNe questions often assume or fix the situation and context; they assume understanding.

A view from another forum:-
“Emergency and Abnormal drills (red / amber issues - actions must do), manufacturer (OEM) originated; ask before changing.
Standard Procedures - operational techniques, ideals, OEM or operator originated; often require adaption to the situation encountered.

The resultant ‘gaps’ between written procedures and adaptive outcome reflect normal operations. There will always be gaps in successful operations; identified after an event, hindsight. A gap is not error.
The outcome of everyday operations are uncertain, variable; crews will have to adapt to achieve a successful outcome - bridging the ‘GAP’.
If the gap is perceived as too large, then check the imagined operational objective, the activity goal, situations which crews are experiencing, the extent of adaption required.
Risk is the amount of uncertainty crews are expected to manage - the ‘GAP’.
Look at normal operations - WAD, write procedures (WAI) based on this; adjust the imagination not the crew.”


From the speakers notes in Airmanship:-
“Airmanship is the ability to act wisely in the conduct of flight operations under difficult conditions.”
“With growing experience Airmanship may grow and blossom into a comfortable protective cloak, resting light upon the shoulders, worn perhaps with pride, but never in vanity, but never giving the protection of 2 inch armour plate.”
With notes: https://www.dropbox.com/s/dt57h800ee...draft.PDF?dl=0
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Old 30th Nov 2021, 21:47
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In the absence of noise /vibration/Fire/smoke close the throttle and ask PM to *Casually visit the cabin*
If they see the engine wind-milling happily, treat it as FADEC/ instrument problem. Not good but not dreadful
If the engine is missing or stopped return very swiftly to cockpit with the news

Now you know which checklist to use
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Old 30th Nov 2021, 22:02
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As it's not the 1950's when jet engines routinely flamed out with no mechanical problem, in any gray area I'd probably lean the way of severe damage. Just a general thought.
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Old 1st Dec 2021, 05:39
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“Airmanship is the ability to act wisely in the conduct of flight operations under difficult conditions.”
“With growing experience Airmanship may grow and blossom into a comfortable protective cloak, resting light upon the shoulders, worn perhaps with pride, but never in vanity, but never giving the protection of 2 inch armour plate.”

Excellent advice.

The Boeing QRH contains a statement somewhere to the effect that no checklist can cover all eventualities and nothing in those manuals precludes the use of good judgement.
My Company documents make it clear that the primary role of the Pilot in Command is to ensure the safe disposition of the aircraft.
In other words use your judgement.
No Sim. Exercise I have done over the last 30 years has involved a non rotation of N1 and N2 that wasn’t a major failure.
Anybody training anything else is indulging in negative training.
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Old 1st Dec 2021, 22:26
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In the 2 airlines I have worked for that operated B737NG’s, no N1 OR N2 rotation was considered a severe damage condition.

Remember the ENG FAIL annunciation is triggered solely by N2 falling below sustainable idle (approx 50%) with the associated start lever in idle. That’s it, there is no clever science behind the annunciation. In isolation, it indicates a flameout or some other ‘innocuous’ failure, where a subsequent restart can be attempted.

ENG FAIL associated with other indications suggesting seizure, separation, abnormal vibration etc require immediate action, I.e. run the severe damage or separation memory items.
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Old 2nd Dec 2021, 07:33
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Jetstream67

I can’t speak for the a320 but all the types I’ve flown the actions for a flameout are the same as for severe damage without fire, the only difference is that for the latter you are doing them at 400’ as memory actions and for the former it is once you’ve cleaned up as an NNC. (Presumably in the a320 ECAM gives you the smae actions either way, I dunni, not rated on it),

thus the only functional difference is whether we are doing the actions urgently from memory or not.

Ambling back into the cabin for a look in slow time is a de facto decision to not treat it as severe damage requiring an immediate secure.
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