Scenario: high engine vibrations on takeoff
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Scenario: high engine vibrations on takeoff
Hello people,
I'd love to have Your thoughts on that one:
Takeoff from a runway for which an engine out departure is prescribed. During gear retraction one engine starts vibrating (Twin narrow body, let's say A320). Procedure calls for thrust reduction till vibrations are below a certain limit. Before actioning the checklist we obviously must ensure the Fly-Navigate-Communicate and a safe height AGL is reached.
Would You: stay on assigned SID or join the engine out procedure?
Question arises from the fact that we do not yet how much thrust we need to reduce on the engine and therefore we could become unable to comply with SID gradient requirements.
Other options are to continue on the SID and assess according to the thrust reduction level or ask vectors towards areas of flatter terrain.
That brings me to the final question: from a performance point of view, is an engine considered "failed" the moment it produces zero thrust or the moment it is unable to produce the required thrust according to the phase of flight?
Thanks for your inputs.
I'd love to have Your thoughts on that one:
Takeoff from a runway for which an engine out departure is prescribed. During gear retraction one engine starts vibrating (Twin narrow body, let's say A320). Procedure calls for thrust reduction till vibrations are below a certain limit. Before actioning the checklist we obviously must ensure the Fly-Navigate-Communicate and a safe height AGL is reached.
Would You: stay on assigned SID or join the engine out procedure?
Question arises from the fact that we do not yet how much thrust we need to reduce on the engine and therefore we could become unable to comply with SID gradient requirements.
Other options are to continue on the SID and assess according to the thrust reduction level or ask vectors towards areas of flatter terrain.
That brings me to the final question: from a performance point of view, is an engine considered "failed" the moment it produces zero thrust or the moment it is unable to produce the required thrust according to the phase of flight?
Thanks for your inputs.
I`go for the EO DEP.Reason; if it gets worse you are already on a safe course and ATC will accomodate it. It won`t `get better`,and when you`ve sorted the vibes you`ll probably either divert or land-back....
ed.If the engine ain`t doing what it should be doing,it`s failed...
argue about it in the bar...`tis better to be down here,wishing you were up there,than up there ,wishing you were down here`...PontiusPilot ,AD 1903
ed.If the engine ain`t doing what it should be doing,it`s failed...
argue about it in the bar...`tis better to be down here,wishing you were up there,than up there ,wishing you were down here`...PontiusPilot ,AD 1903
Based on this info alone I would follow the EO Procedure. Myself and a number of people at the airline I work for say “engine failure, fire or loss of performance, we will follow the EO procedure”
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Your ability to fly the SID assumes you have a certain power setting. If you can't reach that power setting (intentionally or otherwise), I'd think it prudent to fly the EOSID.
Thanks for the question. Hadn't considered that situation before.
Thanks for the question. Hadn't considered that situation before.
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It depends. If terrain is no factor on the SID one might choose to follow the departure (instead of turning back towards a busy airport environment if that is the EOSID). In mountainous terrain I would definitely opt to fly the EOSID. It all depends on the situation, it is never wrong to follow the EOSID, you are always protected.
It comes back to what did you brief for in the event of power loss? It would seem sensible to follow what you’d planned in a time of low workload, unless there was a really good reason not to...
Our SOPs state that an engine that is unable to provide TO/GA thrust is failed. Doesn’t meant that you shouldn’t keep it running, though.
That brings me to the final question: from a performance point of view, is an engine considered "failed" the moment it produces zero thrust or the moment it is unable to produce the required thrust according to the phase of flight?
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Thank You all for your feedbacks.
I second the idea of following the Engine Out Procedure although I was thinking that if the vibrations occur after the diversion point between the SID and the EOProc. (ie. the last common point between both) then we would need to evaluate whether to remain on the SID or rejoin the EOProc. and due consideration should be given to obstacles, MSA and SID gradients to assess the safest course of actions. Do You train this type of scenario in your operations?
I second the idea of following the Engine Out Procedure although I was thinking that if the vibrations occur after the diversion point between the SID and the EOProc. (ie. the last common point between both) then we would need to evaluate whether to remain on the SID or rejoin the EOProc. and due consideration should be given to obstacles, MSA and SID gradients to assess the safest course of actions. Do You train this type of scenario in your operations?
Only half a speed-brake
I think you just have provided the first honestly relevant answer yourself.
If the numbers are done right, the fork point EOSID vs. SID creates two safe routings however there's no transiting from one to the other. The assumption done at the calculation phase is that pilot will choose only one. Looking at the paperwork, you may find the splay area of EOSID is as narrow as 850 m on each side. Not that the edges are made of granite, but the protection is assured only within.
Should this ever actually happen, there will be many options that are equivalently safe to pursue as following the EO-SID. Standing by his commitment of following the most conservative, least risky option that allows for the greatest margins, the PIC will decide accordingly.
What we are discussing here is a mere paper exercise, which has paper-worth answers. Don't get me wrong, they are both valid and required in the pre-flight stage, must be even submitted to gain ops approval. But whoever trains for this better make sure the students will understand well what the limited scope for this exercise really is.
Here's a not-so-curved ball.
Even the language is funny on the wrong side: EO-SID - there's nothing standard about it ... I liked the EFP terminology better.
Some companies have EFPs for absolutely all runways, until 25 NM out and then it ends.
Some insist there is a close end to each of them (holding).
Some use SID's and claim they did the research unless there is EFP
Some say climb straight ahead, we did the research otherwise there would be an EFP.
Some provide the decision point and do the research for SID routing
Some provide the decision point but claim thereafter it's "doable"
Some factor airspace constraints into EFPs, some don't ...
Clear as mud, uh? A 100% proof solution is extremely hard to find and costly to develop. Whereas the real risk and probabilities pose a threat for which a perfect answer is not actually required. One of the many aspects of aviation where getting it absolutely right will make you go insane, yet have a negligible effect for a real-life occurrence should the day ever come.
Training is a finite-resource activity, not only for money and time but also how much will the students correctly remember a year or two later. The subject and amount of detail need to be carefully considered.
If the numbers are done right, the fork point EOSID vs. SID creates two safe routings however there's no transiting from one to the other. The assumption done at the calculation phase is that pilot will choose only one. Looking at the paperwork, you may find the splay area of EOSID is as narrow as 850 m on each side. Not that the edges are made of granite, but the protection is assured only within.
Should this ever actually happen, there will be many options that are equivalently safe to pursue as following the EO-SID. Standing by his commitment of following the most conservative, least risky option that allows for the greatest margins, the PIC will decide accordingly.
What we are discussing here is a mere paper exercise, which has paper-worth answers. Don't get me wrong, they are both valid and required in the pre-flight stage, must be even submitted to gain ops approval. But whoever trains for this better make sure the students will understand well what the limited scope for this exercise really is.
Here's a not-so-curved ball.
Departing LFPG (4 parallel runways), the EO-SID have you cross the departures of the other two runways. Call mayday and advise the turn, let the ATC care about the rest - they say.
Enter your scenario (using A319 loaded for 1 hr sector - she climbs with 5,5 % on one engine at MCT and the other one dead) You only need to retard until 67 N1 where the sore engine starts behaving again. It's a nice autumn VMC...
Is joining the EFP the necessary safest option?Enter your scenario (using A319 loaded for 1 hr sector - she climbs with 5,5 % on one engine at MCT and the other one dead) You only need to retard until 67 N1 where the sore engine starts behaving again. It's a nice autumn VMC...
Even the language is funny on the wrong side: EO-SID - there's nothing standard about it ... I liked the EFP terminology better.
Some companies have EFPs for absolutely all runways, until 25 NM out and then it ends.
Some insist there is a close end to each of them (holding).
Some use SID's and claim they did the research unless there is EFP
Some say climb straight ahead, we did the research otherwise there would be an EFP.
Some provide the decision point and do the research for SID routing
Some provide the decision point but claim thereafter it's "doable"
Some factor airspace constraints into EFPs, some don't ...
Clear as mud, uh? A 100% proof solution is extremely hard to find and costly to develop. Whereas the real risk and probabilities pose a threat for which a perfect answer is not actually required. One of the many aspects of aviation where getting it absolutely right will make you go insane, yet have a negligible effect for a real-life occurrence should the day ever come.
Training is a finite-resource activity, not only for money and time but also how much will the students correctly remember a year or two later. The subject and amount of detail need to be carefully considered.
Last edited by FlightDetent; 18th Aug 2021 at 13:20.
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Loss of Thrust just after airborne on a very heavy plane in IFR in an unfamiliar airport with an SID required a higher than standard climb gradient, I will most likely go for the EOSID.
Otherwise in most cases, especially in good weather , on an overpower modern airliner like the A320 Neo, I would stick to the SID, troubleshoot and request radar vector if required.
Some EOSID are very complexed, and like FlightDetent mentioned you might cross another runway with parallel departure. ATC has no idea what’s your EOSID so another extra workload and a pan pan or mayday call out which might not be required if you just have high engine vibration.
Otherwise in most cases, especially in good weather , on an overpower modern airliner like the A320 Neo, I would stick to the SID, troubleshoot and request radar vector if required.
Some EOSID are very complexed, and like FlightDetent mentioned you might cross another runway with parallel departure. ATC has no idea what’s your EOSID so another extra workload and a pan pan or mayday call out which might not be required if you just have high engine vibration.
Last edited by pineteam; 18th Aug 2021 at 15:10. Reason: Typo
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I would suspect high engine vibration non-normal procedure for most aircraft would involve reducing thrust when flight conditions allow and not now.
I'd be inclined to follow SID (you are outclimbing the PDG with AEO by a significant margin in most cases anyway), clean up, get above the MSA/MRVA and then follow the checklist.
I'd be inclined to follow SID (you are outclimbing the PDG with AEO by a significant margin in most cases anyway), clean up, get above the MSA/MRVA and then follow the checklist.
Only half a speed-brake
Since the regulatory requirement is to prepare for an EF at V1 minus an eyeblink, you can always reduce the engine to idle and then follow a safe EO routing (which may or may not be specifically laid out).
The OP's question is perfectly fine, it's the applicability of the answers where caution needs to be applied.
My take is also to follow the EFP where published unless the crew can ascertain a safe outcome with better margins by doing something else. The initial, full-power altitude gain would open a whole colouring book of options at most places.
How do you decide? It's the F/O's bright knowledge and lucidity combined with captain's gut and situational awareness.
The OP's question is perfectly fine, it's the applicability of the answers where caution needs to be applied.
My take is also to follow the EFP where published unless the crew can ascertain a safe outcome with better margins by doing something else. The initial, full-power altitude gain would open a whole colouring book of options at most places.
How do you decide? It's the F/O's bright knowledge and lucidity combined with captain's gut and situational awareness.
Last edited by FlightDetent; 18th Aug 2021 at 18:26.
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FlightDetent. Agreed 100%. If it is a place where I would be familiar I would most likely follow the SID or ask vectors. If in doubt: EOSID is a safe option. In my airline, the EOSID is very “standard”. Climb to EO acceleration altitude and turn to a fix located at or near the airport unless not possible due terrain.
At least in the Boeing world, high vibe indications - by itself - did not require immediate crew action. Rather, it was informational and to be used with other engine indications to determine if there was an actual engine issue (one exception - on the RB211, high vibes could justify a shutdown due to the potential for catastrophic bearing failure leading to an uncontained engine failure).
That being said, seeing high vibes on the gauge is not the same as feeling the entire airframe shake...
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I was told (CFM-56 at that time) the LP spool will give you airframe shake, unlike the HP where indication without perceived vibration needs to be taken into account straight away.
tdracer, does that resemble any of your experience?
Indeed, anything we're allowed to do in commercial air transport is based on the n-1 scenario, taking idle thrust and following the trajectory for EO is always a safe (enough) option. Some choices are less optimal than others (e.g. the 737 divert to Iran) but on a bad day you might need to take them.
tdracer, does that resemble any of your experience?
Indeed, anything we're allowed to do in commercial air transport is based on the n-1 scenario, taking idle thrust and following the trajectory for EO is always a safe (enough) option. Some choices are less optimal than others (e.g. the 737 divert to Iran) but on a bad day you might need to take them.
giord
As others have laid out, it depends very much on the depth of the analysis your company performance department has done. For us, we get options out to where you’ve made MSA and can continue/divert/return but once on the EOP we need to stick with it, as it could be going in a completely different direction to the SID, and to get from one to the other might involve flying through rock (and a heavy application of the Uncertainty Principle).
A typical EOP might read something like:
Engine failure before XXXXX, follow SID to XXXXX then turn left to ABC to hold or return
Engine failure after XXXXX but before YYYYY turn left to ABC to hold or return
Engine failure after YYYYY continue with SID until above MSA then continue or return
As others have laid out, it depends very much on the depth of the analysis your company performance department has done. For us, we get options out to where you’ve made MSA and can continue/divert/return but once on the EOP we need to stick with it, as it could be going in a completely different direction to the SID, and to get from one to the other might involve flying through rock (and a heavy application of the Uncertainty Principle).
A typical EOP might read something like:
Engine failure before XXXXX, follow SID to XXXXX then turn left to ABC to hold or return
Engine failure after XXXXX but before YYYYY turn left to ABC to hold or return
Engine failure after YYYYY continue with SID until above MSA then continue or return
FlyingStone
finally, someone with some sense. While y’all are pulling thrust levers down low and making rushed diagnoses about vibrations… this guy calmly climbs to MSA, undertakes some analysis and calls for the appropriate checklist. Bravo!
it’s just vibrating, there’s most likely no recalls (type dependant obviously), it’s producing thrust and the airplane is flying just fine. Make the airplane safe i.e. fly it somewhere away from hills and do the appropriate checklist.
finally, someone with some sense. While y’all are pulling thrust levers down low and making rushed diagnoses about vibrations… this guy calmly climbs to MSA, undertakes some analysis and calls for the appropriate checklist. Bravo!
it’s just vibrating, there’s most likely no recalls (type dependant obviously), it’s producing thrust and the airplane is flying just fine. Make the airplane safe i.e. fly it somewhere away from hills and do the appropriate checklist.
*The RB211 was the exception because it was potentially safety of flight. Three spool engines are a bearing design nightmare, and Rolls has had it's fair share of bearing issues. On the RB211-524, there were several instances where one of the fan shaft bearings would overheat - leading to an oil fire that quite literally cut the fan shaft in half. First time it happened, center engine on an L1011 - the fan departed the rest of the engine and tried to saw the aircraft in half. They landed safely thanks to some good piloting and good luck, but it was a near thing. Rolls instituted a 'fan catcher' (sort of like a disc brake) to prevent the fan from departing the engine if it happened again - which it did on a 747. Fan catcher worked as advertised, but the unloaded turbine rev-ed to well over redline and disintegrated - peppering the wing with shrapnel (fortunately without causing catastrophic damage). Anyway, a vibe limit was instituted on the RB211 - vibes over some limit mandated an immediate shutdown (I think it was fan vibe only but wouldn't swear to it).
