Citation Biggin Crash any news on why yet ?
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But despite its careful, thorough work, the AAIB still doesn't know why things happened like they did. They only know what happened, not why. There were no recorders of any kind on board.
The Board's call for CVR/FDR might get heard this time.
Good summary here: Mystery Citation crash revives calls for recorders on business jets
The Board's call for CVR/FDR might get heard this time.
Good summary here: Mystery Citation crash revives calls for recorders on business jets
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To me, it reads like they interpreted the noise/vibration from the aircon system as an engine failure, shut down the suspect engine, but due to the damaged throttle assembly shut down both engines, and did not have enough time to restart either of them.
Or, they interpreted the noise/vibration from the aircon system as an engine failure, shut down one engine (not knowing which one it was that "was" making the noise), then (when the problem did not go away) they shut down the second one but before the first one restarted (which would seem a bizzare error) and the damaged throttle assembly is a redherring. And did not have enough time to restart either of them.
Does that make sense to CJ pilots here?
If both engines were OK after all, they could have just ignored the racket and landed back. Were they getting odd engine instrument indications?
Or, they interpreted the noise/vibration from the aircon system as an engine failure, shut down one engine (not knowing which one it was that "was" making the noise), then (when the problem did not go away) they shut down the second one but before the first one restarted (which would seem a bizzare error) and the damaged throttle assembly is a redherring. And did not have enough time to restart either of them.
Does that make sense to CJ pilots here?
If both engines were OK after all, they could have just ignored the racket and landed back. Were they getting odd engine instrument indications?
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Hi!
I'm on standby today and had time to read the whole report, and yes it does. What I don't like in the report is the "engine restart drills" they talk about. If by "drills" they mean items to be performed from memory, then they are wrong: There are no memory items in the Citation checklist for engine restarts (unless the 500 is totally different from the 550 and 560 that I fly, but it's the same type rating, so I can't imagine). You are supposed to work through the checklist.
The same with engine shutdown due to vibration. No memory items / "drills". Follow the checklist. In case of engine fire there are memory items, but you aren't supposed to shut the engine down right away. You go to idle first and see what happens (could be the wrong engine or a bleed air leak). Very strange that they shut them down so quickly (at least the one with the working shutoff lever). In the report it says that no checklists were found in the wreckage. So they either did everything from memory (maybe confusing things with aircraft types they were more familiar with since the pilot in the left hand seat had only recently converted to the type?) or that the checklists burnt up.
Regards, Max
Does that make sense to CJ pilots here?
The same with engine shutdown due to vibration. No memory items / "drills". Follow the checklist. In case of engine fire there are memory items, but you aren't supposed to shut the engine down right away. You go to idle first and see what happens (could be the wrong engine or a bleed air leak). Very strange that they shut them down so quickly (at least the one with the working shutoff lever). In the report it says that no checklists were found in the wreckage. So they either did everything from memory (maybe confusing things with aircraft types they were more familiar with since the pilot in the left hand seat had only recently converted to the type?) or that the checklists burnt up.
Regards, Max
True, the single engine restart checklist has no memory items for the 500, 550 or 560, but the two engine restart checklist does, and it's the same in all three cases:
Emergency restart - two engines:
(starred items are memory items)
*1 - IGNITION - Both ON
*2 - BOOST PUMPS - Both ON
*3 - THROTTLES - Idle
*4 - If alt. allows: AIRSPEED - increase to 200 KIAS
5 - FIREWALL SHUTOFF - check OPEN
6 - ANTI-ICE SWITCHES - all OFF
7 - If no start in 10 secs, either START BUTTON - press momentarily.
(I've left out the notes associated with the cx)
The Bravo cx is slightly different, in that only the first three items are memory items.
Emergency restart - two engines:
(starred items are memory items)
*1 - IGNITION - Both ON
*2 - BOOST PUMPS - Both ON
*3 - THROTTLES - Idle
*4 - If alt. allows: AIRSPEED - increase to 200 KIAS
5 - FIREWALL SHUTOFF - check OPEN
6 - ANTI-ICE SWITCHES - all OFF
7 - If no start in 10 secs, either START BUTTON - press momentarily.
(I've left out the notes associated with the cx)
The Bravo cx is slightly different, in that only the first three items are memory items.
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Severe engine 'vibration' with associated problems identifying which one.
Does this not remind one of Kegworth to some extent?
The various thrust settings referred to in the report suggest to me that different power settings were being tried before a shutdown. Is that how others read it?
Sir George Cayley.
Does this not remind one of Kegworth to some extent?
The various thrust settings referred to in the report suggest to me that different power settings were being tried before a shutdown. Is that how others read it?
Sir George Cayley.
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The ACM seems to have been the source of the vibration. Either engine would effect the bleed air being processed. If the fuel cut off could have been inadvertently selected on one engine, coupled with a change in the vibration, flying very low level, vibration still exists, wrong engine? Restart? The whole scenario is very alarming, even when sitting in front of the TV at home let alone being in that situation. I am sure they done all they could as competant pilots, they were trying to return to land. There is no evidence that the engines would not have got them there, unfortunately they did not have the information available to us now, a couple of years after the fact. Also, I don't care about the circumstances of the flight, not my business, and I do not think it has any direct bearing on the cause. Just sad to say bye to more good people.
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As I understand the report, the pilot got into a state of having both engines shut down due to a faulty thrust control (broken rivet).
The report highlights a relight procedure problem which can catch the unwary, it is only possible to relight one engine at a time and if the first relight has not fully completed any attempt to start relighting the second will cause BOTH to abort.
This seems rather
daft to me, surely it would be more sensible to simply inhibit or delay the second relight until the first has completed ?.
The report highlights a relight procedure problem which can catch the unwary, it is only possible to relight one engine at a time and if the first relight has not fully completed any attempt to start relighting the second will cause BOTH to abort.
This seems rather
daft to me, surely it would be more sensible to simply inhibit or delay the second relight until the first has completed ?.
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AAIB findings
Both pilots were qualified and licensed to operate the aircraft. By having a mentor pilot on-board the PIC showed himself to be safety aware. The report sees no need to mention the legalities of the operation of the flight which means that these factors had no relevance to the accident. By making safety rec 2010-15 it seems that the AAIB believe the aircraft manufacturer should do more to make pilots aware of the possibility of aborting engine restarts unintentionally.
As with all air accidents, this report shows that it is a sequence of unforeseen events that caused the loss. Had these events occurred uniquely or in isolation they would not have caused the aircraft to crash. Some may say that it was bad luck.
As with all air accidents, this report shows that it is a sequence of unforeseen events that caused the loss. Had these events occurred uniquely or in isolation they would not have caused the aircraft to crash. Some may say that it was bad luck.
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Hello!
That broken rivet only explains why the left hand engine might have been accidentally shut down, because it allowed the throttle lever to be moved past idle into cutoff. The right hand throttle lever did not show this fault, so shutdown of this engine must have been deliberate.
I don't think it's daft as the same logic applies to other systems of the Citation as well, e.g. the fire extinguishers: That engine whose fire button is pressed _last_ will get the extinguishers. This is rehearsed numerous times during simulator courses in connection with aircraft evacuation with (suspected) engine fire.
And the same applies to the starters: Since the battery is not strong enough to operate both starters in parallel, the starter that was selected _last_ gets the current. This is taught in the initial type rating course.
Not their day. Whatever. But then we can save our money for future accident investigations, because some degree of bad luck (but there is no such thing as "luck" in the universe) is always involved in accidents. In a world filled with good luck alone, there would be no accidents, because however stupidly one behaves, the good luck will always save the day.
I think the report's conclusion is very valid, that all turbine powered aircraft (btw. why not _all_ aircraft, regardless of their means of propulsion?) should be equipped with data and voice recorders. Gadgets like the iPod show, that solid state recording devices can be mass-produced at very low prices, adding only a small amount to the cost of flying. Some intercoms already come with "clearance recorders" bulit into them. All that is needed is an increase of memory size for a two-figure amount in Dollars/Pounds/Euros.
In this case, the cause of the accident is not the unsuccessful restart of the engines, but the previous act of shutting them down. And only a voice recorder could tell us, why the crew decided to do that when they were already positioned on (right) downwind, flying slowly at very low level in good weather for a visual landing.
Happy landings,
max
As I understand the report, the pilot got into a state of having both engines shut down due to a faulty thrust control (broken rivet).
The report highlights a relight procedure problem which can catch the unwary, it is only possible to relight one engine at a time and if the first relight has not fully completed any attempt to start relighting the second will cause BOTH to abort.
This seems rather
daft to me, surely it would be more sensible to simply inhibit or delay the second relight until the first has completed ?.
This seems rather
daft to me, surely it would be more sensible to simply inhibit or delay the second relight until the first has completed ?.
And the same applies to the starters: Since the battery is not strong enough to operate both starters in parallel, the starter that was selected _last_ gets the current. This is taught in the initial type rating course.
Some may say that it was bad luck.
I think the report's conclusion is very valid, that all turbine powered aircraft (btw. why not _all_ aircraft, regardless of their means of propulsion?) should be equipped with data and voice recorders. Gadgets like the iPod show, that solid state recording devices can be mass-produced at very low prices, adding only a small amount to the cost of flying. Some intercoms already come with "clearance recorders" bulit into them. All that is needed is an increase of memory size for a two-figure amount in Dollars/Pounds/Euros.
In this case, the cause of the accident is not the unsuccessful restart of the engines, but the previous act of shutting them down. And only a voice recorder could tell us, why the crew decided to do that when they were already positioned on (right) downwind, flying slowly at very low level in good weather for a visual landing.
Happy landings,
max
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Possible scenario
The shut-down of both engines was obviously inadvertent. The PIC hears the vibrations and considers engine malfunction as the cause. Given his seating position it would be natural to try the left engine first. Retarding left engine first doesn't rectify the problem. Unknown to him he has cut-off fuel supply to left engine because missing rivet head doesn't stop the throttle lever at the idle stop. He reapplies full left hand power and retards right engine.Due to no bleed air entering the ACM vibration stops. Believing he has rectified the problem he cuts fuel to right hand engine. Now he discovers he has two inoperative engines. In the limited time available he has to decide which one to restart. High workload in the cockpit. Within the time available he has one chance to relight the correct engine and climb away from 150ft. On his own that would have been a true feat of airmanship, all decisions made in an instant.
Now add two crew. Does PIC delegate engine restart procedure to PM or does PM as the more experienced pilot take control? Did PM offer to retard right hand engine before PIC could tell him that he inadvertently closed down the left hand engine?
AAIB do not speculate on the two crew issue so we have to assume they give it no relevance.
In all honesty who could predict that a faulty bearing in an ACM could lead to two engines being shut down, one inadvertently, whilst flying at 1,000ft agl?
Bad luck does some times play a part in accidents. The correct response to this bad luck is to try and eliminate as much of it as possible for future flights which the AAIB report attempts to do with its safety recs.
Now add two crew. Does PIC delegate engine restart procedure to PM or does PM as the more experienced pilot take control? Did PM offer to retard right hand engine before PIC could tell him that he inadvertently closed down the left hand engine?
AAIB do not speculate on the two crew issue so we have to assume they give it no relevance.
In all honesty who could predict that a faulty bearing in an ACM could lead to two engines being shut down, one inadvertently, whilst flying at 1,000ft agl?
Bad luck does some times play a part in accidents. The correct response to this bad luck is to try and eliminate as much of it as possible for future flights which the AAIB report attempts to do with its safety recs.
In this case, the cause of the accident is not the unsuccessful restart of the engines, but the previous act of shutting them down. And only a voice recorder could tell us, why the crew decided to do that when they were already positioned on (right) downwind, flying slowly at very low level in good weather for a visual landing.
asdf1234:
Your possible scenario does make sense of the facts.
I noticed in reading the section on the pilots' experience that the co-pilot had no multi-crew training or experience, and was flying in a "mentor" role. He would also have little or no experience flying from the RHS in any aircraft, let alone the C500. I wonder whether this may also have contributed?
The "mentor" pilot might have felt an obligation to take over PF duties as the situation deteriorated. He might have then unexpectedly discovered that he couldn't reach the igniters, boost pumps starter buttons without unbuckling his seat belt, so would then have had to revert to relying on LHS to carry out those functions. I can imagine that crew co-operation could degenerate very quickly.
The AAIB did not discuss the lack of multi-crew experience of the mentor, but then I suppose this would have been out of their remit, given that the LHS pilot was licenced to operate the aircraft single-pilot.
FWIW, if flying in RHS as mentor pilot on light single-pilot jets, I think the emergency briefing needs to be carefully thought through. The simplistic PF/PNF division of responsibilities is not necessarily the best procedure if the PF is in the LHS but not very experienced on the aircraft.
Your possible scenario does make sense of the facts.
I noticed in reading the section on the pilots' experience that the co-pilot had no multi-crew training or experience, and was flying in a "mentor" role. He would also have little or no experience flying from the RHS in any aircraft, let alone the C500. I wonder whether this may also have contributed?
The "mentor" pilot might have felt an obligation to take over PF duties as the situation deteriorated. He might have then unexpectedly discovered that he couldn't reach the igniters, boost pumps starter buttons without unbuckling his seat belt, so would then have had to revert to relying on LHS to carry out those functions. I can imagine that crew co-operation could degenerate very quickly.
The AAIB did not discuss the lack of multi-crew experience of the mentor, but then I suppose this would have been out of their remit, given that the LHS pilot was licenced to operate the aircraft single-pilot.
FWIW, if flying in RHS as mentor pilot on light single-pilot jets, I think the emergency briefing needs to be carefully thought through. The simplistic PF/PNF division of responsibilities is not necessarily the best procedure if the PF is in the LHS but not very experienced on the aircraft.
Last edited by Trim Stab; 23rd May 2010 at 12:50.
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AAIB do not speculate on the two crew issue so we have to assume they give it no relevance.
In all honesty who could predict that a faulty bearing in an ACM could lead to two engines being shut down...
Like "Pilot A", I have flown piston twins for a long time before moving to the Citation (he had flown the Pa31 in the five or so years before getting type-rated on the Citation). With a piston twin, flying low and slow as they did, your only chance to get out of trouble is to shut down / feathering the malfunctioning engine as quickly as possible. Especially with some Pipers where a locking pin prevents the propeller from feathering once the RPM has dropped below a certain figure. Maybe this explains the haste with which the engine(s) was/were shut down? Without a voice recording, we will never know.
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Farnborough Air Crash (March 2008) report
Spent some time last week reading the linked pdf of the AAIB report
BBC News - Missing rivet head 'caused Farnborough jet crash'
I struggle to understand what happened - looks like there was an associated vibration that caused the pilots to shut down one engine, then the second engine was accidentally shut down possibly because of a missing rivet head, when they only intended to reduce its speed.
Would a pilot really shut down an engine totally because of suspected vibration without being 100% sure? Sounds sadly like a repeat of the BMI crash on the A1 from the ? 1980's ?
BBC News - Missing rivet head 'caused Farnborough jet crash'
I struggle to understand what happened - looks like there was an associated vibration that caused the pilots to shut down one engine, then the second engine was accidentally shut down possibly because of a missing rivet head, when they only intended to reduce its speed.
Would a pilot really shut down an engine totally because of suspected vibration without being 100% sure? Sounds sadly like a repeat of the BMI crash on the A1 from the ? 1980's ?
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Would/should you really shut down one engine not having 100% established the cause of vibration when you had only just got airborne and were so close to landing? Looks like shades of the BMI crash on the A1 all over again to me.... close down a good engine then something untoward shuts down the other one.
I also read the pdf of the AAIB Report in full on Friday-Saturday and the crash seems a total mystery to me. Did the ACM bearings really give up after just a minute or two into this flight, with no previous anomalies in the previous flight? Was one engine shut down totally within a few seconds of the vibrations being noticed? Worrying stuff, to me
I also read the pdf of the AAIB Report in full on Friday-Saturday and the crash seems a total mystery to me. Did the ACM bearings really give up after just a minute or two into this flight, with no previous anomalies in the previous flight? Was one engine shut down totally within a few seconds of the vibrations being noticed? Worrying stuff, to me
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Hamish.
I think you are right about there being shades of Kegworth, but there are many significant differences.
The report has to use a lot of circumstantial evidence but it seems to suggest that a bearing failure on the (ACM) Air Cycle Machine caused significant vibration. The engine displays do not have VIB gauges, so trying to figure out the problem was always going to be difficult.
The ACM speed has a direct link to the engine thrust, so when a thrust lever was retarded, it probably led to a decrease in vibration. Confirmation bias possibly and R engine shutdown.
As the thrust on the L engine was reduced to enter the circuit, the fuel cutoff lever may have moved into the "cutoff" position due to the missing / failed rivet that allowed the lever to travel thought the cutoff gate unimpeded.
Double engine failure. Emergency checklist for double engine failure could have been clearer as attempts to start the 2nd engine too soon after a start attempt on the 1st results in the starters disengaging on both engines. If sufficiently accelerated the 1st engine may start (but at a slower rate) and the 2nd engine will have to be attempted again. It is suggested that a start could take 85sec to achieve a start to a point where full power would be available.
These guys seemed to have got the engines started, but the thrust available was not sufficient to power them out of the very low altitude they found themselves at (approx 100' below airfield level)
The report seem to emphasise the importance of flying at the best lift/drag speed to achieve the optimal time and distance available for dealing with the problem.
All in all these guys found themselves in a difficult position which then got worse & worse. I agree that shutting down an engine when not 100% certain is very questionable; but the report could only guess at what symptoms they were presented with that led them to that decision.
T'Bug
I think you are right about there being shades of Kegworth, but there are many significant differences.
The report has to use a lot of circumstantial evidence but it seems to suggest that a bearing failure on the (ACM) Air Cycle Machine caused significant vibration. The engine displays do not have VIB gauges, so trying to figure out the problem was always going to be difficult.
The ACM speed has a direct link to the engine thrust, so when a thrust lever was retarded, it probably led to a decrease in vibration. Confirmation bias possibly and R engine shutdown.
As the thrust on the L engine was reduced to enter the circuit, the fuel cutoff lever may have moved into the "cutoff" position due to the missing / failed rivet that allowed the lever to travel thought the cutoff gate unimpeded.
Double engine failure. Emergency checklist for double engine failure could have been clearer as attempts to start the 2nd engine too soon after a start attempt on the 1st results in the starters disengaging on both engines. If sufficiently accelerated the 1st engine may start (but at a slower rate) and the 2nd engine will have to be attempted again. It is suggested that a start could take 85sec to achieve a start to a point where full power would be available.
These guys seemed to have got the engines started, but the thrust available was not sufficient to power them out of the very low altitude they found themselves at (approx 100' below airfield level)
The report seem to emphasise the importance of flying at the best lift/drag speed to achieve the optimal time and distance available for dealing with the problem.
All in all these guys found themselves in a difficult position which then got worse & worse. I agree that shutting down an engine when not 100% certain is very questionable; but the report could only guess at what symptoms they were presented with that led them to that decision.
T'Bug
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What is the procedure in a twin jet, if an engine problem is suspected?
In a single engine aircraft, you obviously continue flying under power, to the nearest plausible landing point, regardless of what the engine is doing (short of an engine fire, perhaps).
But in a twin, should one always attempt to idle / shut down one engine (one at a time, obviously) to see if a problem goes away?
I suppose, knowing nothing about these light jets, that the drawback of doing nothing (and treating it like the SE case, and returning to the airport under power) is that if an engine does have a real fault and disintegrates in an uncontained manner and shreds the control cables, you lose the tail control surfaces which is obviously very bad news, or maybe it could damage/ignite fuel lines. Otherwise, why would anybody want to shut down an engine at all?
I also do not understand the comments about the LHS being licensed to fly the aircraft alone. Judging from the passengers, this was "obviously" a charter flight, and all charters need 2 pilots for a jet. Was it not a charter flight, or is there some other factor there? What if the passengers did not pay for the flight but were carried for free?
In a single engine aircraft, you obviously continue flying under power, to the nearest plausible landing point, regardless of what the engine is doing (short of an engine fire, perhaps).
But in a twin, should one always attempt to idle / shut down one engine (one at a time, obviously) to see if a problem goes away?
I suppose, knowing nothing about these light jets, that the drawback of doing nothing (and treating it like the SE case, and returning to the airport under power) is that if an engine does have a real fault and disintegrates in an uncontained manner and shreds the control cables, you lose the tail control surfaces which is obviously very bad news, or maybe it could damage/ignite fuel lines. Otherwise, why would anybody want to shut down an engine at all?
I also do not understand the comments about the LHS being licensed to fly the aircraft alone. Judging from the passengers, this was "obviously" a charter flight, and all charters need 2 pilots for a jet. Was it not a charter flight, or is there some other factor there? What if the passengers did not pay for the flight but were carried for free?
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For jets shut down is the only option, sometimes if the jet just flames out with no associated 'bangs' or vibrations etc, then maybe go for a restart.
Not sure what to say about pistons, I had a partial failure with some vibration once but elected not to shut down and use what power it was giving to RTB asap, turned out to be a bent push rod/stuck valve ( in retrospect I would have shut down, I spent all that time doing that exercise on test and then come the day I didn't do as my training dictated.
Not sure what to say about pistons, I had a partial failure with some vibration once but elected not to shut down and use what power it was giving to RTB asap, turned out to be a bent push rod/stuck valve ( in retrospect I would have shut down, I spent all that time doing that exercise on test and then come the day I didn't do as my training dictated.