A captains dilemma re engine precautionary in-flight shut down
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A captains dilemma re engine precautionary in-flight shut down
ATSB report just out.
On 10 November 2009 at around 1900 EST, a Boeing Company 737-467 aircraft, registered VH-TJY, departed Brisbane Airport, Queensland for Melbourne, Victoria. As the aircraft was climbing through 24,000 ft, the flight crew observed abnormal indications associated with the right engine. The aircraft was returned to Brisbane where it landed without further incident.
Engine disassembly and inspection revealed significant damage to the stage-1 low-pressure turbine (LPT). Analysis of the stage-1 LPT blades showed that some blades had sustained levels of thermally-induced microstructural degradation, which may have affected the creep resistance of the alloy and resulted in the blades being susceptible to failure by creep rupture.
Creep rupture was identified as the likely failure mechanism in previous stage-1 LPT blade failures in this engine type investigated by the Australian Transport Safety Bureau and the engine manufacturer. As a result of this occurrence and at the time of writing this report, the engine manufacturer is revising service bulletin SB 72-1113 to expand the range of blade manufacturing batch numbers that had previously been identified as being predisposed to creep-related failure. Blades in the identified batches are to be withdrawn from service as soon as they are next removed from the engine.
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From reading the above, it sounds like a non-event although photos of the engine damage would make any pilot sit up and take notice. The crew read all the right checklists and because the engine settled down after it was throttled back, an in-flight shut down was averted. However, despite this decision in-flight to keep the defective engine running, once the aircraft landed the crew then shut down the engine while taxiing in "as a precaution".
It is many years since this scribe flew jet transports so his comments may be seen by others as outdated and from another era. But there are lessons from the past valid even now. Readers may recall the case of the 737-400 that a long time ago crashed short of East Midlands airport in England killing many passengers. Indeed that particular accident has been used in many CRM and TEM publications as an example of a fatal stuff up by the crew.
Severe vibration caused the crew to shut down an engine during cruise. Mis-identification of the faulty engine was made by both the captain and first officer and the `good` engine was inadvertently shut down. During the descent from cruise altitude with both thrust levers at idle (closed) the severe vibration on the faulty engine practically disappeared. The crew firmly believed the correct engine had been shut down.
During subsequent radar vectors to the ILS (aircraft now on one engine), and after gear and flap selection had been made, power was increased on what the crew blissfully thought was the good engine. To their surprise it failed completely on power application and the 737 crashed into a motorway embankment a few hundred metres from the runway. In other words it was only when power was applied to the defective engine did it give up the ghost.
Turning now to the ATSB report on the QF 737 incident it seems the crew decided not to close down the defective engine and instead leave the close-down until after landing. This ties in with the QRH which states in general that the object is to attempt to recover normal engine operation or shut down the engine if recovery is not possible. Further, the book says run the engine normally or at a reduced thrust setting which is surge and stall free.
In other words, if the engine is running normally at idle there is no need to shut it down. Which is what happened with QF - except the crew were sufficiently concerned about the engine to shut it down after landing during the taxi in.
One could speculate what would happen if for some reason the aircraft was required to go-around from final approach. Would the crew apply go-around thrust to both engines and risk re-occurrence of the same problem that caused them to use the QRH in the first place? Or would they make a single engine approach with the defective engine at idle and if a go-around was needed it would be on one engine while leaving the defective engine at idle?
From reading similar incident reports over the years, one is struck by the reluctance of crews to make an in-flight shut down - even though post flight investigations revealed significant damage to the engine concerned. Could it be that crews are reluctant to shut down an engine because of perceived media publicity that invariably follows? (lots of aviation mad people with VHF scanners only too eager to ring up the local media). The ensuing media publicity then alarms the PR people forced to defend the airline image? The danger is the crew could be hung out to dry for upsetting the corporate image.
It used to be that a precautionary in-flight shut down was considered good airmanship because one could never be certain of the extent of engine damage. On the other hand in today's skies, precautionary in-flight engine shut downs can put the crew in the invidious situation of first weighing up good airmanship versus undesirable consequences from management charged with the responsibility of fending off a rapacious media eager for a headline scoop.
On 10 November 2009 at around 1900 EST, a Boeing Company 737-467 aircraft, registered VH-TJY, departed Brisbane Airport, Queensland for Melbourne, Victoria. As the aircraft was climbing through 24,000 ft, the flight crew observed abnormal indications associated with the right engine. The aircraft was returned to Brisbane where it landed without further incident.
Engine disassembly and inspection revealed significant damage to the stage-1 low-pressure turbine (LPT). Analysis of the stage-1 LPT blades showed that some blades had sustained levels of thermally-induced microstructural degradation, which may have affected the creep resistance of the alloy and resulted in the blades being susceptible to failure by creep rupture.
Creep rupture was identified as the likely failure mechanism in previous stage-1 LPT blade failures in this engine type investigated by the Australian Transport Safety Bureau and the engine manufacturer. As a result of this occurrence and at the time of writing this report, the engine manufacturer is revising service bulletin SB 72-1113 to expand the range of blade manufacturing batch numbers that had previously been identified as being predisposed to creep-related failure. Blades in the identified batches are to be withdrawn from service as soon as they are next removed from the engine.
............................................................ ..........................
From reading the above, it sounds like a non-event although photos of the engine damage would make any pilot sit up and take notice. The crew read all the right checklists and because the engine settled down after it was throttled back, an in-flight shut down was averted. However, despite this decision in-flight to keep the defective engine running, once the aircraft landed the crew then shut down the engine while taxiing in "as a precaution".
It is many years since this scribe flew jet transports so his comments may be seen by others as outdated and from another era. But there are lessons from the past valid even now. Readers may recall the case of the 737-400 that a long time ago crashed short of East Midlands airport in England killing many passengers. Indeed that particular accident has been used in many CRM and TEM publications as an example of a fatal stuff up by the crew.
Severe vibration caused the crew to shut down an engine during cruise. Mis-identification of the faulty engine was made by both the captain and first officer and the `good` engine was inadvertently shut down. During the descent from cruise altitude with both thrust levers at idle (closed) the severe vibration on the faulty engine practically disappeared. The crew firmly believed the correct engine had been shut down.
During subsequent radar vectors to the ILS (aircraft now on one engine), and after gear and flap selection had been made, power was increased on what the crew blissfully thought was the good engine. To their surprise it failed completely on power application and the 737 crashed into a motorway embankment a few hundred metres from the runway. In other words it was only when power was applied to the defective engine did it give up the ghost.
Turning now to the ATSB report on the QF 737 incident it seems the crew decided not to close down the defective engine and instead leave the close-down until after landing. This ties in with the QRH which states in general that the object is to attempt to recover normal engine operation or shut down the engine if recovery is not possible. Further, the book says run the engine normally or at a reduced thrust setting which is surge and stall free.
In other words, if the engine is running normally at idle there is no need to shut it down. Which is what happened with QF - except the crew were sufficiently concerned about the engine to shut it down after landing during the taxi in.
One could speculate what would happen if for some reason the aircraft was required to go-around from final approach. Would the crew apply go-around thrust to both engines and risk re-occurrence of the same problem that caused them to use the QRH in the first place? Or would they make a single engine approach with the defective engine at idle and if a go-around was needed it would be on one engine while leaving the defective engine at idle?
From reading similar incident reports over the years, one is struck by the reluctance of crews to make an in-flight shut down - even though post flight investigations revealed significant damage to the engine concerned. Could it be that crews are reluctant to shut down an engine because of perceived media publicity that invariably follows? (lots of aviation mad people with VHF scanners only too eager to ring up the local media). The ensuing media publicity then alarms the PR people forced to defend the airline image? The danger is the crew could be hung out to dry for upsetting the corporate image.
It used to be that a precautionary in-flight shut down was considered good airmanship because one could never be certain of the extent of engine damage. On the other hand in today's skies, precautionary in-flight engine shut downs can put the crew in the invidious situation of first weighing up good airmanship versus undesirable consequences from management charged with the responsibility of fending off a rapacious media eager for a headline scoop.
Last edited by A37575; 20th Jul 2011 at 06:47.
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A37575, at the risk of over simplifying what is in reality a fairly complex issue, I would say (whilst sitting on the fence) that it depends.
Flying with 2 engines tends to focus the mind in this circumstance, as opposed to flying with 3 or 4 for starters.
Its also worth noting that the philosophy behind not shutting down the troublesome donk (as I understand it) is to retain many of the ancillary redundancies present even when its being run at idle....however for all intents and purposes you are flying a S/E aircraft with a slightly more powerful APU.
With respect to shutting the engine down after landing, again I'd submit that now being on the ground, the perception would likely be "we don't need it AS much" anymore, and after all, what negative outcome is likely to occur?
For me, thats the beauty of having an infinitely adaptable yet fallible human on the flight deck, rather than a far less adaptable Cylon driving
Flying with 2 engines tends to focus the mind in this circumstance, as opposed to flying with 3 or 4 for starters.
Its also worth noting that the philosophy behind not shutting down the troublesome donk (as I understand it) is to retain many of the ancillary redundancies present even when its being run at idle....however for all intents and purposes you are flying a S/E aircraft with a slightly more powerful APU.
With respect to shutting the engine down after landing, again I'd submit that now being on the ground, the perception would likely be "we don't need it AS much" anymore, and after all, what negative outcome is likely to occur?
For me, thats the beauty of having an infinitely adaptable yet fallible human on the flight deck, rather than a far less adaptable Cylon driving
What is the problem here??????
So they elected to keep the suspect engine at idle power and therefore available should the s*** really hit the other fan.
After landing it wouldn't matter if the s*** hit the other fan so they shut the suspect engine down.........Sounds like good decision making to me.
Get a life...
Next
So they elected to keep the suspect engine at idle power and therefore available should the s*** really hit the other fan.
After landing it wouldn't matter if the s*** hit the other fan so they shut the suspect engine down.........Sounds like good decision making to me.
Get a life...
Next
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Never flown with more than 2 engines, and I've been taught to never shut 1 down unless its patently obvious that its more dangerous to keep it running. Ancillary services eg a genny, bleed source, anti ice are all still available in the meantime, and of course its still there if the other one fails.
Just because its behaving non normally doesnt necessarily mean it wont get you 'round the circuit or over a hill if you actually need it.
I grew up on PT-6's which have demonstrated many a time that they will run quite happily with what has subsequently found to be quite horrific damage.
Just because its behaving non normally doesnt necessarily mean it wont get you 'round the circuit or over a hill if you actually need it.
I grew up on PT-6's which have demonstrated many a time that they will run quite happily with what has subsequently found to be quite horrific damage.
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'holic has said, and I quote...
"I've noticed in a lot of your posts you seem to support management's strategy to get rid of experienced pilots and engineers and replace them with cheaper/less experienced alternatives.
Your post is a perfect example of the absolute ignorance management have of operational issues. You're just putting on display that you don't even know what you don't know."
Would you like to expand on that and give some examples?
"I've noticed in a lot of your posts you seem to support management's strategy to get rid of experienced pilots and engineers and replace them with cheaper/less experienced alternatives.
Your post is a perfect example of the absolute ignorance management have of operational issues. You're just putting on display that you don't even know what you don't know."
Would you like to expand on that and give some examples?
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Get a life...
Next
Next
.
Whatever bud.
The post above heavily "second guessed" the crew in what was obviously an abnormal situation well handled to a safe outcome.
The poster was implying it should have been handled differently.
The post above heavily "second guessed" the crew in what was obviously an abnormal situation well handled to a safe outcome.
The poster was implying it should have been handled differently.
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I'm with nitpicker.
The engine was kept available for use if required, the remaining engine is always suspect. [ALL engines are suspect]
It was shutdown on the ground to prevent any further damage as it was no longer needed.
Sounds like good Command decisions to me!
The engine was kept available for use if required, the remaining engine is always suspect. [ALL engines are suspect]
It was shutdown on the ground to prevent any further damage as it was no longer needed.
Sounds like good Command decisions to me!
Tee Emm +1.
Nitpicker, regardless of what your opinion of the OP was,
was totally uncalled-for. I suggest you think about taking your own advice.
If I had the choice, I'd keep it running for the services it was "generating". Even if to couldn't develop any meaningful thrust, it might help if the other decided to kark it (I'm not familiar with 737 systems). Certainly, when on the ground, it becomes redundant so shut it down pronto to save any further damage.
Nitpicker, regardless of what your opinion of the OP was,
Get a life...
Next
Next
If I had the choice, I'd keep it running for the services it was "generating". Even if to couldn't develop any meaningful thrust, it might help if the other decided to kark it (I'm not familiar with 737 systems). Certainly, when on the ground, it becomes redundant so shut it down pronto to save any further damage.
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One must weigh up the risk of adding the complexities of asymmetric flight when it comes to the decision of conducting a shut-down or to continue running.
Yes we are trained to handle single engine flight and we may be flying aircraft with guaranteed performance, but chosing to shut down an engine that is still running and significantly increase the workload may be a risk far greater than continuing to run a somewhat unhealthy engine. The command decision is what we are trained for, experienced in and paid to make.
A3, whilst I have no knowledge on the 73, I imagine some of the questions you pose may be difficult to answer, for example
That scenario would possibly be a "circumstance dependant" sort of thing- the guys up front surely would have considered their actions and planned accordingly.
I would hazard a guess as plan/expect single engine, and use only what is available on the other without fiddling with it too much. But as you said, one could speculate.
It is cheaper to replace an engine (which may be buggered anyway!) than the alternative which could be far worse- willingly going asymmetric when it may not have been necessary and screwing it up.
haughtney1, waren9, I like what you have posted
Yes we are trained to handle single engine flight and we may be flying aircraft with guaranteed performance, but chosing to shut down an engine that is still running and significantly increase the workload may be a risk far greater than continuing to run a somewhat unhealthy engine. The command decision is what we are trained for, experienced in and paid to make.
A3, whilst I have no knowledge on the 73, I imagine some of the questions you pose may be difficult to answer, for example
One could speculate what would happen if for some reason the aircraft was required to go-around from final approach. Would the crew apply go-around thrust to both engines and risk re-occurrence of the same problem that caused them to use the QRH in the first place? Or would they make a single engine approach with the defective engine at idle and if a go-around was needed it would be on one engine while leaving the defective engine at idle?
I would hazard a guess as plan/expect single engine, and use only what is available on the other without fiddling with it too much. But as you said, one could speculate.
It is cheaper to replace an engine (which may be buggered anyway!) than the alternative which could be far worse- willingly going asymmetric when it may not have been necessary and screwing it up.
haughtney1, waren9, I like what you have posted
than the alternative which could be far worse- willingly going asymmetric when it may not have been necessary and screwing it up.
From reading similar incident reports over the years, one is struck by the reluctance of crews to make an in-flight shut down - even though post flight investigations revealed significant damage to the engine concerned.
Grandpa Aerotart
Just suppose you are inbound to LHR in a B767 and the entirety of the UK and Western Europe is down to Cat 2 and 3 weather - it does happen - its happened to me.
A B767 on one engine is limited to Cat 1 weather - its not certified for SE autoland.
As you track past Frankfurt (Vis 150m cloud base 100' in blowing snow) one engine starts to act up - vibration indicators all over the shop, generally unstable engine parameters. You disconnect the AT and reduce the thrust lever on the suspect engine back to idle. The vibration goes away and the idle engine parameters stabilise at acceptable values.
If the Crew decide to shut the engine down - because they have done 100s of assy approaches and landing in the sim - WTF are they going to land? Well they could fly 800nm back to Romania or Turkey, where the weather was Cat 1, 2 hours ago, on one engine, and hope it keeps running over all that awful weather, and the Alps.
Or they might decide, since the vibration and engine parameters were REALLY eye catching BEFORE they reduced thrust to idle, to declare a pan and divert into FRA and AUTOLAND because they can - until they shut down that engine - which is still producing electricity and bleed air for anti icing.
Or they might decide since the exceedances were not extreme to continue on towards LHR, with that engine at reduced thrust, in the knowledge that they have a multitude of CAT 3b capable airports between them and LHR, about every 10-15 minutes in fact, where they can autoland if needed...provided they DON'T shut the engine down.
The minute you shut down an engine you MUST divert and land at 'the nearest suitable airport'. If, having reduced the engine to idle thrust, its no longer misbehaving you DON'T...you have options...you could quite legitimately fly the 1 hr or so from abeam Frankfurt, past Cologne, Brussels and 10 other suitable airports, and land at your destination, LHR, and only THEN shut down the problem engine as you taxi in.
The VERY first serious question your Fleet C&Ting management and safety department will ask you, having shut down the engine and flown 800nm to a Cat 1 weather airport in Romania - probably by phone 'cause its gonna be about a week before they see you in person - is "What were the engine instrument readings after you, VERY properly, reduced thrust to idle?"
"Ahh...well...they were all in the green"
"Ok....well we will see you when you get back"
They then spend the next x days until you turn up at BS Castle for your tea and bikkies discussing amongst themselves why you are about the biggest moron mother nature ever breathed life into...and how many 10s of 1000s of $ your lack of judgement has cost the company.
The above scenario is just one where a crew, having looked at all options, could quite legitimately decide to not shut down a misbehaving engine until after they land.
Its what airline pilots are paid to do. Take into account ALL factors...including commercial factors...before making the safest/best decision.
Maybe the crew of the 737 in the thread starter's post looked at the NAV display and saw the 'nearest suitable' airport was Tamworth and said "Fck that...its running ok now at idle thrust...we go to BNE where the ground staff are, and the engineers, food, our own beds, the whores and beer are better - so we operate it on reduced thrust until it ****s itself OR BNE IS the nearest suitable, or we land"
Flawless logic and command judgment
A B767 on one engine is limited to Cat 1 weather - its not certified for SE autoland.
As you track past Frankfurt (Vis 150m cloud base 100' in blowing snow) one engine starts to act up - vibration indicators all over the shop, generally unstable engine parameters. You disconnect the AT and reduce the thrust lever on the suspect engine back to idle. The vibration goes away and the idle engine parameters stabilise at acceptable values.
If the Crew decide to shut the engine down - because they have done 100s of assy approaches and landing in the sim - WTF are they going to land? Well they could fly 800nm back to Romania or Turkey, where the weather was Cat 1, 2 hours ago, on one engine, and hope it keeps running over all that awful weather, and the Alps.
Or they might decide, since the vibration and engine parameters were REALLY eye catching BEFORE they reduced thrust to idle, to declare a pan and divert into FRA and AUTOLAND because they can - until they shut down that engine - which is still producing electricity and bleed air for anti icing.
Or they might decide since the exceedances were not extreme to continue on towards LHR, with that engine at reduced thrust, in the knowledge that they have a multitude of CAT 3b capable airports between them and LHR, about every 10-15 minutes in fact, where they can autoland if needed...provided they DON'T shut the engine down.
The minute you shut down an engine you MUST divert and land at 'the nearest suitable airport'. If, having reduced the engine to idle thrust, its no longer misbehaving you DON'T...you have options...you could quite legitimately fly the 1 hr or so from abeam Frankfurt, past Cologne, Brussels and 10 other suitable airports, and land at your destination, LHR, and only THEN shut down the problem engine as you taxi in.
The VERY first serious question your Fleet C&Ting management and safety department will ask you, having shut down the engine and flown 800nm to a Cat 1 weather airport in Romania - probably by phone 'cause its gonna be about a week before they see you in person - is "What were the engine instrument readings after you, VERY properly, reduced thrust to idle?"
"Ahh...well...they were all in the green"
"Ok....well we will see you when you get back"
They then spend the next x days until you turn up at BS Castle for your tea and bikkies discussing amongst themselves why you are about the biggest moron mother nature ever breathed life into...and how many 10s of 1000s of $ your lack of judgement has cost the company.
The above scenario is just one where a crew, having looked at all options, could quite legitimately decide to not shut down a misbehaving engine until after they land.
Its what airline pilots are paid to do. Take into account ALL factors...including commercial factors...before making the safest/best decision.
Maybe the crew of the 737 in the thread starter's post looked at the NAV display and saw the 'nearest suitable' airport was Tamworth and said "Fck that...its running ok now at idle thrust...we go to BNE where the ground staff are, and the engineers, food, our own beds, the whores and beer are better - so we operate it on reduced thrust until it ****s itself OR BNE IS the nearest suitable, or we land"
Flawless logic and command judgment
Last edited by Chimbu chuckles; 20th Jul 2011 at 17:27.
Grandpa Aerotart
F25 or F30...both permitted. Would depend on weight.
Given that it WAS permitted to do a one eng inop autoland IF the engine failed AFTER APP mode engaged AND F25 or F30 selected do you really think it would be an issue to do a F30 autoland with one at flight idle and the other operating normally?
Given that it WAS permitted to do a one eng inop autoland IF the engine failed AFTER APP mode engaged AND F25 or F30 selected do you really think it would be an issue to do a F30 autoland with one at flight idle and the other operating normally?
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Centaurus, whilst I see your point quite clearly, mistakes still can happen. The original post highlighted something similar- the shut-down of the wrong engine in the 737 to East Midlands; afterall the crew there probably would have done, to adjust your quote, "well over one hundred engine shutdown drills in the simulator".