Catastrophic structural failure
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Catastrophic structural failure
I was just reading the very sad thread about the accident at Coventry and it got me thinking that that isn't the first time I've read about serious accidents either happening or being narrowly averted due to some sort of failure of this type.
This concerns me...
The pilot is expected to check their a/c over before flying and that should make the spotting of a jammed control, for example, likely (along with full & free checks pre-t/o, of course), but spotting a likely folding wing is going to be more difficult (assuming there aren't visible gaps in airframe etc.).
Surely there's a reason why a/c need to be checked, serviced and overhauled as often as they do?! I think there are enough things to think about in flying - worrying over a wing dropping off all the time could just be enough to take the fun out of this!
Who is responsible for the structural safety of an a/c at the end of the day - an engineer or the pilot in command? And if the latter (pilot is ALWAYS responsible for safety of any passengers, right?), then how can we be certain of structural integrity if the a/c is not owned by us but by a club or group, for example?
And am I being over-reactive about this or is it a more widespread concern?
I hasten to add this is not intended to be or to provoke an 'engineer-bashing' thread
Hersh
This concerns me...
The pilot is expected to check their a/c over before flying and that should make the spotting of a jammed control, for example, likely (along with full & free checks pre-t/o, of course), but spotting a likely folding wing is going to be more difficult (assuming there aren't visible gaps in airframe etc.).
Surely there's a reason why a/c need to be checked, serviced and overhauled as often as they do?! I think there are enough things to think about in flying - worrying over a wing dropping off all the time could just be enough to take the fun out of this!
Who is responsible for the structural safety of an a/c at the end of the day - an engineer or the pilot in command? And if the latter (pilot is ALWAYS responsible for safety of any passengers, right?), then how can we be certain of structural integrity if the a/c is not owned by us but by a club or group, for example?
And am I being over-reactive about this or is it a more widespread concern?
I hasten to add this is not intended to be or to provoke an 'engineer-bashing' thread
Hersh
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You HAVE to trust the last engineer who looked at it. The usual pre-flight checks will only pick up obvious things, or obvious cases of malicious damage.
Most engineers are very good. On any airfield, the "monkeys" (if any) will be well known so if you are in charge of maintaining a plane, ask around first.
With club planes flown by many others, perhaps you have the extra assurance that if it is dodgy, somebody else is likely to get killed first!
Having said this, structural failures / control problems are extremely rare. If they weren't then I would never fly because something like that is a virtually certain death.
Most engineers are very good. On any airfield, the "monkeys" (if any) will be well known so if you are in charge of maintaining a plane, ask around first.
With club planes flown by many others, perhaps you have the extra assurance that if it is dodgy, somebody else is likely to get killed first!
Having said this, structural failures / control problems are extremely rare. If they weren't then I would never fly because something like that is a virtually certain death.
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Statutory Instrument 2000 No. 1562
The Air Navigation Order 2000
Pre-flight action by commander of aircraft
43 The commander of an aircraft registered in the United Kingdom shall reasonably satisfy himself before the aircraft takes off:
....
(c) that the aircraft is in every way fit for the intended flight, and that where a certificate of maintenance review is required by article 10(1) of this Order to be in force, it is in force and will not cease to be in force during the intended flight;
Note the use of the word "reasonably".
Mike
The Air Navigation Order 2000
Pre-flight action by commander of aircraft
43 The commander of an aircraft registered in the United Kingdom shall reasonably satisfy himself before the aircraft takes off:
....
(c) that the aircraft is in every way fit for the intended flight, and that where a certificate of maintenance review is required by article 10(1) of this Order to be in force, it is in force and will not cease to be in force during the intended flight;
Note the use of the word "reasonably".
Mike
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I think you just have to ask yourself 'how often does this happen?' I personally know of only one such incident, and that was casued by 2 pilots aerobatting a non-aerobatic aircraft. They paid the ultimate price.
There have been lots of incidences of structural failure after loss of control in IMC or very severe turbulence, but structural failures (this weekend's tragedy apart, where we don't yet know the cause) where the aeroplane has not exceeded its design limts are (AFAIK) just about non existant.
Anyone know of any?
SSD
There have been lots of incidences of structural failure after loss of control in IMC or very severe turbulence, but structural failures (this weekend's tragedy apart, where we don't yet know the cause) where the aeroplane has not exceeded its design limts are (AFAIK) just about non existant.
Anyone know of any?
SSD
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Yes. Failure of the main wing spar in a Robin DR400 in 1997. The weather was calm, the aircraft was flown well within its limits, and there was no evidence of previous damage. Four people died.
It was blamed on poor manufacturing quality.
It was blamed on poor manufacturing quality.
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For what it's worth, and I don't have the exact quote to hand, Pilot recently ran an article on Robins and mentioned the DR400 accident in France. IIRC, the magazine said that the assumption was that the aeroplane had been involved in an unreported incident earlier in it's life where it was overstressed or involved in a ground collision.
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The BEA (French AAIB) said it was "very unlikely" that the failure was due to any previous damage.
There was a lot of muddying of the waters after this accident. Initially the pilot was blamed for having performed aerobatics during the accident flight. This was later discounted by eye witnesses, and by the radar trace.
It would suit everyone for the explanation to be pilot error or previous damage, as the alternative is worrying. Since the accident report was published, all DR400's have had their operating category downgraded from U to N, and have to undergo an inspection of the spar.
It has to be kept in proportion, though. One failure, in many hundreds of thousands hours operation - including plenty where the aircraft must have been overloaded or overstessed.
There was a lot of muddying of the waters after this accident. Initially the pilot was blamed for having performed aerobatics during the accident flight. This was later discounted by eye witnesses, and by the radar trace.
It would suit everyone for the explanation to be pilot error or previous damage, as the alternative is worrying. Since the accident report was published, all DR400's have had their operating category downgraded from U to N, and have to undergo an inspection of the spar.
It has to be kept in proportion, though. One failure, in many hundreds of thousands hours operation - including plenty where the aircraft must have been overloaded or overstessed.
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Does anyone know what happened to the Arrow at Thruxton a couple of years ago. Didn't its wing fold in day VFR straight and level? That was scary as I was due to be checked out on that.
Also, doesn't the CAP10B have a history of wing spar failiures following particularly aggressive yet legal aeros?
Also, doesn't the CAP10B have a history of wing spar failiures following particularly aggressive yet legal aeros?
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The Cap 10B has had some spar failures, but generally caused by overstressing either on the accident flight or a previous flight.
The one I fly has a recording G meter, and club-imposed limits of +4.5 and -3g. Woe betide anyone who exceeds them! In France, parachutes are mandatory for aeros. Despite the monitoring and low G limits, I'm not sure I'd be happy to aerobat the Cap without one.
The one I fly has a recording G meter, and club-imposed limits of +4.5 and -3g. Woe betide anyone who exceeds them! In France, parachutes are mandatory for aeros. Despite the monitoring and low G limits, I'm not sure I'd be happy to aerobat the Cap without one.
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Indeed, I know a CAP10B part owner in France, who, having reached a certain age, has completely stopped flying his CAP due to the aggressive flying by his co-owners. I used to go up with them and one guy, an ex Jaguar pilot used to load on 5 or 6g very sharply, at low level, thus rendering our parchutes virtually useless should the wing have folded. I remember one time spinning quite low, the engine quit (when we took off the low fuel lights were on), so he dived vertically at 180kts (near Vne?) pumping the throttle and the prop just turned enought to restart. Then he pulled out over the field very low and very very fast. I have to admit it was fun at the time, but I wouldn't do it again although that has more to do with the aircraft than the pilot, who happened to be exceptionally skilled. We once did 8 landings 0.3 by doing light bulb shaped 180 turn backs at about 80 ft at each end of the runway (nill wind of course).
Good old remote French airfield, no authorities, no rules, no radio and virtually no witnessess!
Sorry babbling on like that...!
Good old remote French airfield, no authorities, no rules, no radio and virtually no witnessess!
Sorry babbling on like that...!
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Aerobatic Flyer,
Our Aeroclub has a DR400-140B and Ive seen the Notice from the DGAC regarding the accident etc, but it isnt much of a report on the accident itself, just mentions it as the reason for the need to get the spar checked and refrain from certain manouvers etc...and of course the guys at the club have about ten different versions of the events cause.... muddying waters...
Do you happen to know if the Accident report is available online anywhere – preferably in english as though my french has improved no end since being here it isnt perfect by anyones standards!!
Regards, SD..
Our Aeroclub has a DR400-140B and Ive seen the Notice from the DGAC regarding the accident etc, but it isnt much of a report on the accident itself, just mentions it as the reason for the need to get the spar checked and refrain from certain manouvers etc...and of course the guys at the club have about ten different versions of the events cause.... muddying waters...
Do you happen to know if the Accident report is available online anywhere – preferably in english as though my french has improved no end since being here it isnt perfect by anyones standards!!
Regards, SD..
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skydriller
The accident report is available on-line in French here.
I don't know if there is an english translation, so... here's my translation of a few bits:
Hypotheses
Overstressing....... "this hypothesis is improbable".
Failure due to previous damage...... "not very probable".
A slight precision here... the overstressing hypothesis is "improbable", while the failure due to previous damage is "très peu probable" in the original French. That's not as strong as "improbable". A good lawyer could be gainfully employed arguing about it. In fact, many probably are....
The hypothesis that failure followed a progressive weakening of the main wing spar is the most probable.
Cause of the accident
The accident was caused by the failure in flight of the right wing.
The gluing and assembly defects found are the determining cause of this failure, through weakening and accelerated ageing of the structures concerned, which lowered their resistance to authorised load factors.
The DR400 is the mainstay of French flying club fleets. A lot of influential people argued against any blame being approtioned to the aircraft, and the arguments are not over yet. But, as I said, it has to be kept in proportion. I still fly DR400's quite happily, and would always choose one in preference to a PA28 - despite the latter's stronger wings!
The accident report is available on-line in French here.
I don't know if there is an english translation, so... here's my translation of a few bits:
Hypotheses
Overstressing....... "this hypothesis is improbable".
Failure due to previous damage...... "not very probable".
A slight precision here... the overstressing hypothesis is "improbable", while the failure due to previous damage is "très peu probable" in the original French. That's not as strong as "improbable". A good lawyer could be gainfully employed arguing about it. In fact, many probably are....
The hypothesis that failure followed a progressive weakening of the main wing spar is the most probable.
Cause of the accident
The accident was caused by the failure in flight of the right wing.
The gluing and assembly defects found are the determining cause of this failure, through weakening and accelerated ageing of the structures concerned, which lowered their resistance to authorised load factors.
The DR400 is the mainstay of French flying club fleets. A lot of influential people argued against any blame being approtioned to the aircraft, and the arguments are not over yet. But, as I said, it has to be kept in proportion. I still fly DR400's quite happily, and would always choose one in preference to a PA28 - despite the latter's stronger wings!
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There was an accident many years back (Robin I think) where the pilot had hit a haystack on landing. Everything looked fine but the spar had been fractured and it failed structurally on the next flight.
Probably in the old AAIB bulletins somewhere.
In fact ... here it is .....
G-DELS accident report
Probably in the old AAIB bulletins somewhere.
In fact ... here it is .....
G-DELS accident report
Last edited by PPRuNe Radar; 3rd Jun 2003 at 05:25.
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Plug for Cirrus Design
This sort of failure mode, either catastrophic physical collapse
or loss of key control surfaces does happen and is a significant
contributor to fatal accidents in light aircraft.
I fly a Cirrus which incorporates a BRS whole-body parachute
system which gives the pilot an extra option for survival in
what would otherwise be fatal incidents...
These are now becoming available for retrofitting to most
light-single GA aircraft...check them out!
-- Andrew
or loss of key control surfaces does happen and is a significant
contributor to fatal accidents in light aircraft.
I fly a Cirrus which incorporates a BRS whole-body parachute
system which gives the pilot an extra option for survival in
what would otherwise be fatal incidents...
These are now becoming available for retrofitting to most
light-single GA aircraft...check them out!
-- Andrew
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I think there are many light aircraft pilots who would be happy to have a ballistic parachute fitted to their aircraft. I would, at least it gives you an option if the wings do fall off.
You wouldn't dream of crossing the channel on a ferry with no lifeboats....
Cheers
EA
You wouldn't dream of crossing the channel on a ferry with no lifeboats....
Cheers
EA
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Looks like I'll be avoiding the DR400, then!
If nothing else, this kind of thing goes to show how much more important it is to speak up as a group or club flyer if you think you've had a heavy landing/minor taxiing collision than to try and avoid the embarrasment.
If nothing else, this kind of thing goes to show how much more important it is to speak up as a group or club flyer if you think you've had a heavy landing/minor taxiing collision than to try and avoid the embarrasment.
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Aerobatic Flyer,
Thanks for that, much appreciated.
Hersham boy,
All I can say is, if you get the chance to fly in a Robin, grab it! Your view of the DR400 would definitely change if you have flown one. In comparison to a PA28 or Cessna, well, there is no comparison as the robin is IM Humble opinion much more fun & enjoyable to fly. I learnt to fly in C152s & PA28s in the UK and switched to Robins (unavoidable!) when I came to France.
Regards, SD..
Thanks for that, much appreciated.
Hersham boy,
All I can say is, if you get the chance to fly in a Robin, grab it! Your view of the DR400 would definitely change if you have flown one. In comparison to a PA28 or Cessna, well, there is no comparison as the robin is IM Humble opinion much more fun & enjoyable to fly. I learnt to fly in C152s & PA28s in the UK and switched to Robins (unavoidable!) when I came to France.
Regards, SD..
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On a similar vein, does anyone know of any cases of structural failure of a Tipsy Nipper? I regularly aerobat one, sticking to within its limits (+4g on a permit/No inverted system therefore no negative). I gather the wing is immensely strong.
I have read the 'Tipsy Nipper Story' book and it mentions quite a few fatals, but I believe all due either to mishandling/bad luck after engine failure or low-level aeros. I can't find any mention of structural failure.
Any more info would be appreciated.
CRX
I have read the 'Tipsy Nipper Story' book and it mentions quite a few fatals, but I believe all due either to mishandling/bad luck after engine failure or low-level aeros. I can't find any mention of structural failure.
Any more info would be appreciated.
CRX
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DR400
THe DR400 is a fabulous aircraft with over 10 million flying hours to its credit.
There s great controversy surrounding the in-flight break up in France.
According to Guy Pellisier of Robin - lovely bloke - whilst they did find evidence of inadequate adhesive contact area in the examination of the wreckage, the structure was still deemd to exceed its design parameters.
It is a difficult inspection that requires an opening cut into the box spar, ironically risking weakening the structure a lot more than any insufficent adhesion that they have found thus far.
They have found more aircraft - either side of the accident machine - that were bonded less than adequately by modern methods/ increased inspections etc.
However, still none have been found that fail to meet the design parameters.
This is an unfortunate incident that has dealt Robin (Apex) a real blow - some say unfairly.
I dont speak for Robin, I may have got the story wrong. However, My DR400 Regent - a Jan 01 model (fully featured in Todays Pilot July 01) - continues to give me and my passengers enormous pleasure.
If you want a pleasant surprise - step out of your spammer and give one a go.
Check out the numbers too - huge range, impressive speed (on fixed gear/ prop), great lifting capabilities and all out of a farm strip if necessary.
If you are in the Midlands, or want to travel, are genuinely in the market for a brand new plane and want to talk to a totally satisfied customer as opposed to a salesman - I'll take you for a ride.
All the best
HP
There s great controversy surrounding the in-flight break up in France.
According to Guy Pellisier of Robin - lovely bloke - whilst they did find evidence of inadequate adhesive contact area in the examination of the wreckage, the structure was still deemd to exceed its design parameters.
It is a difficult inspection that requires an opening cut into the box spar, ironically risking weakening the structure a lot more than any insufficent adhesion that they have found thus far.
They have found more aircraft - either side of the accident machine - that were bonded less than adequately by modern methods/ increased inspections etc.
However, still none have been found that fail to meet the design parameters.
This is an unfortunate incident that has dealt Robin (Apex) a real blow - some say unfairly.
I dont speak for Robin, I may have got the story wrong. However, My DR400 Regent - a Jan 01 model (fully featured in Todays Pilot July 01) - continues to give me and my passengers enormous pleasure.
If you want a pleasant surprise - step out of your spammer and give one a go.
Check out the numbers too - huge range, impressive speed (on fixed gear/ prop), great lifting capabilities and all out of a farm strip if necessary.
If you are in the Midlands, or want to travel, are genuinely in the market for a brand new plane and want to talk to a totally satisfied customer as opposed to a salesman - I'll take you for a ride.
All the best
HP
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If you want a pleasant surprise - step out of your spammer and give one a go.
It's not all that good on short strips, though. Perhaps with a different prop it would be better, but initial acceleration and climb is a bit slow.