Engine vibration on AIRBUS aircrafts

[b767300]

What do you guys thinks about this:-
HIGH ENGINE VIBRATION REF 3.02.70 P26

under IF NO ICING CONDITIONS EXISTS
ENG PARAMETERS ----> CHECK
check engine parameters especially EGT, crosscheck with other engines.

IF RAPID INCREASE ABOVE THE ADVISORY
flight condition permitting, reduce N1 to maintain vibration below advisory threshold.

NOTE: if the VIB indication does not decrease following thrust reduction, this may indicate other problem on the engine.
APPLY ADEQUATE PROCEDURE...

This is what it says more or less in the FCOM.

The question is what is ADEQUATE PROCEDURE ????
is that to say SHUTDOWN the engine from MEMORY?

becuase in AIRBUS there is no checklist to SHUTDOWN an engine.

[Preppy]

My understanding of the A320 Airbus engine vibration policy is that:

1. An engine vibration on its own, doesn't require a shut down.
2. If you have throttled back the engine (not in icing conditions) and there is still high vibration, then this may indicate other problems. In that case APPLY APPROPRIATE PROCEDURE.
3. If in doubt, use AIRMANSHIP/CRM to resolve problem.

QED :ok:

Preppy

[NigelOnDraft]

As Preppy says, in general do not shutdown purely for a VIB indication. Try and find if something else might be the cause of it...? Or a false indication...?

Of course, if the thing is shaking you to bits, then TL Reduce, and/or -> Idle, and if that does not help, then HP Off ("Engine Master" in Airbus speak), tends to solve the immediate problem, even in an Airbus (!)

Don't lose sight of the basics <G>

NoD

[FlapsOne]

There is a procedure in the FCOM.


FCOM 3.2.70

ENG 1(2) SHUT DOWN
Apply the ENG SHUT DOWN procedure, if damage, or if engine relight unsuccessful.

If high vibration occurs and continues after engine shutdown, reduce airspeed and descend to a safe altitude.

Attempt to determine and use a pratical airspeed and altitude for minimum vibrations.

The actual Shut Down procedure follows.

[lomapaseo]

Attempt to determine and use a pratical airspeed and altitude for minimum vibrations.

Keeping in mind that a rotating machine acts like a critical speed item where a specific windmill speed range would be worse rather than higher or lower.

[Tristar]

FlapOne
Please remember that your statement is from “Eng Fail” check list & what b767300 is referring to, is Pure and simple Engine VIB.
As far as I know there is no check list(AIRBUS 320/340) that mandates an engine shut down no matter how high is the VIB, as long as it is not associated with other abnormalities i.e. EGT, N1, N2 Over limit etc. etc.
I fully agree with Preppy especially point number 3. “If in doubt, use AIRMANSHIP/CRM to resolve problem”. The last thing we need is for pilots to go and shut down engines just because of VIB especially as that engine might be a vital source of air, electric and/or hydraulic power. ( Oh that reminds me this is the only day off I have in which I can get my car’s wheels balanced, they have been vibrating my bottom for the past 3 month, actually I think I’m beginning to enjoy it.)
:ok:

[FlapsOne]

Tristar

I agree up to a point.

The bottom line is, if YOU decide - based on all available info (airmanship) - to shut down an engine, that checklist should be used.

The observation was, that a shut down checklist doesn't exist, but it does. It's up to the Captain when to use it.

[Tristar]

FlapsOne

1) I respect your opinion and you are entitled to it. However my opinion is different, I cannot for example use the “cockpit windshield/window cracked” check list to descend for i.e. crew oxygen showing zero.

2) I know b767300 personally and we talked about the VIB problem, and our main concern is that certain trainers/captains think that an engine should be shut down simply because of high VIB which could be accompanied with airframe VIB.

But saying all that at the end of the day in an emergency you do what you like and feel is right for that particular situation; provided you walk away from it and able to give the proper excuses later.

[FlapsOne]

Tristar

I don't think we differ that much. The point is, when do you consider increasesd vibration (plus whatever other indications) as an indication of engine damage requiring shutdown.

I would personally requires something more than vibration indications alone to help me in that decision. I share your concern about your trg capts' view.

That said, if I had concluded that the engine was in some way damaged (based on ALL of the available information) I would use that checklist from 3.2.70.

Apply the ENG SHUT DOWN procedure, if damage , or if engine relight unsuccessful

[mcdhu]

This is an interesting one which comes up in the sim regularly.

Picture the scene: in the sim, just after T/o the thing starts to shake (vibrate). Out comes the QRH - Abnormals - Power Plant - High Engine Vibration - 2.24 and off you go as discussed above.

You read the notes and are (almost) invariably not in icing conditions so you retard the thrust lever as called for in the QRH. The whole thing is now shaking like mad, the readings are off scale (9.9+) and the purser is telling you that the punters are terrified. No other 'adequate procedure' is showing on Ecam. You think the thing is going to shake itself to bits. You discuss engine shutdown with the Pnf and decide that, despite the bold 'VIB detection alone does not require engine shutdown', that is precisely what you are going to do.

''Shutdown no1/2,'' you cry!

''That's not a memory item,'' retorts the pnf, ''See 3.02.01 P2 which says Wshr,Gpws, loss of braking, Emer Descent and beginning of Unreliable Speed Indication are the only ones I must remember!''

'OK,' you cry. 'No1/2 Thrust Lever is closed, No1/2 Eng Master Off, Eng1/2 Fire P/b push!' - with appropriate confirmations, of course!

As NoD says, common sense has prevailed.
Strangely enough, peace and quiet is then restored and you can set about planning your SE ILS or whatever the T/IRE wants to see this time round.

I think what Airbus are actually saying is that if it is that bad, there will be other indications eg low oil press, fire etc which will give you the 'adequate' (perhaps 'appropriate' would have been a better translation) procedure including how to shut the engine down.

Hope this adds to the topic,
Cheers,
mcdhu

[lomapaseo]

History has shown that the worse persistent engine vibration have occured to an engine that is shutdown and windmilling at specific aircraft speed (above or below and it quiets down) in spite of this no serious structural aircraft damage has occured (ignoring the upset passengers).

This same history has shown that it is extremely rare for running engine vibrations, felt in the cockpit, to seriously harm an aircraft if left running for several minutes, however over a half hour or so you might expect an engine fuel line or hydraulic pump to fall off.

Therefore it is the considered recommendations of the manufacturers that you not be hasty in shutting down engines that have only a single gage annomaly of high vibration with not even a tactile feel.