Tiger down off Straddie
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"Faaaaaarrk!", said the crows, as Graham Kennedy was known to say .. HTH would you pick up minute fractures in the threaded section of tie rods - apart from magnafluxing?? 
Sounds like there's a possibility someone might have specified an incorrect steel specification for the replacement tie rods?
The only way threaded sections fracture in this manner, is if;
1. The steel used does not have adequate tensile strength ..
2. The steel used is too brittle and does not have adequate elongation abilities under load stress ..
3. The steel used is affected too readily by minute amounts of corrosive attack, thus creating a reduction in cross-section thickness (and surprisingly to many, high tensile steels corrode much more readily than low-grade steels).
H37869A - Fuselage Joint "H" Tie Rod
There's also a major difference between hot-rolled threads and threads cut on a lathe. Hot-rolled threads are inherently stronger, because the grain in the steel follows the thread form - whereas a lathe cuts the grain, and thereby weakens the grain structure.
Sounds like there's a possibility someone might have specified an incorrect steel specification for the replacement tie rods?
The only way threaded sections fracture in this manner, is if;
1. The steel used does not have adequate tensile strength ..
2. The steel used is too brittle and does not have adequate elongation abilities under load stress ..
3. The steel used is affected too readily by minute amounts of corrosive attack, thus creating a reduction in cross-section thickness (and surprisingly to many, high tensile steels corrode much more readily than low-grade steels).
H37869A - Fuselage Joint "H" Tie Rod
There's also a major difference between hot-rolled threads and threads cut on a lathe. Hot-rolled threads are inherently stronger, because the grain in the steel follows the thread form - whereas a lathe cuts the grain, and thereby weakens the grain structure.
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Sounds like there's a possibility someone might have specified an incorrect steel specification for the replacement tie rods?
The only way threaded sections fracture in this manner, is if;
1. The steel used does not have adequate tensile strength ..
2. The steel used is too brittle and does not have adequate elongation abilities under load stress ..
3. The steel used is affected too readily by minute amounts of corrosive attack, thus creating a reduction in cross-section thickness (and surprisingly to many, high tensile steels corrode much more readily than low-grade steels).
H37869A - Fuselage Joint "H" Tie Rod
There's also a major difference between hot-rolled threads and threads cut on a lathe. Hot-rolled threads are inherently stronger, because the grain in the steel follows the thread form - whereas a lathe cuts the grain, and thereby weakens the grain structure.
The only way threaded sections fracture in this manner, is if;
1. The steel used does not have adequate tensile strength ..
2. The steel used is too brittle and does not have adequate elongation abilities under load stress ..
3. The steel used is affected too readily by minute amounts of corrosive attack, thus creating a reduction in cross-section thickness (and surprisingly to many, high tensile steels corrode much more readily than low-grade steels).
H37869A - Fuselage Joint "H" Tie Rod
There's also a major difference between hot-rolled threads and threads cut on a lathe. Hot-rolled threads are inherently stronger, because the grain in the steel follows the thread form - whereas a lathe cuts the grain, and thereby weakens the grain structure.
One Cowley built Tiger Moth did come under scrutiny in the late summer of 1941 when operating with 17 EFTS Peterborough. In the rear seat, the pupil heard a loud crack and watched bemused as the starboard lower wing detached from its root end pickup on the lower longeron. The instructor only realized his pupil had bailed out when he saw the descending parachute, at which point the aircraft broke up and he too abandoned what had become a spinning fuselage, which devoid of all wings, landed on a house in Peterborough town alongside the engine which had already buried itself in the garden.
Flying at 17 EFTS was suspended for two days while the fuselage tie rods of the entire fleet were examined in detail partly by engineers wielding magnets. There was some suspicion that during assembly or later maintenance, tie rods manufactured from Dural instead of high tensile steel had been installed or substituted and the whiff of sabotage as much as carelessness in quality control was prevalent, although the engineering staff was never advised of the outcome.
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So, a probable cause is established with OT and JS providing plausible, possible reasons. Good work, what's next? Will it now get complicated, does 'steel' and manufacturing need to be analysed, followed by a paperwork check to see if any 'suspect' parts are fitted and replaced if they are identified. Or will it involve the whole fleet in a health check?
Liked the bit in JS post where young Bloggs just bails out, bugger this for a game of soldiers says he; wonder how many beers that cost him. Good bit of kit the parachute, even if uncomfortable sit on.
Liked the bit in JS post where young Bloggs just bails out, bugger this for a game of soldiers says he; wonder how many beers that cost him. Good bit of kit the parachute, even if uncomfortable sit on.
Well, for further engineering analysis there is always John Fall's beautiful CAD model of the 'Moth.
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CASA Proposed AD
DH 82 (Tiger Moth) Series Aeroplanes
PAD/DH 82/17 - Lateral Fuselage Tie Rods - Removal and Replacement
http://www.casa.gov.au/wcmswr/_asset...h%2082-017.pdf
I can't open it. Site too busy!
Edit
URL fixed.
It applies to DH60, DH82, and DH83
DH 82 (Tiger Moth) Series Aeroplanes
PAD/DH 82/17 - Lateral Fuselage Tie Rods - Removal and Replacement
http://www.casa.gov.au/wcmswr/_asset...h%2082-017.pdf
I can't open it. Site too busy!
Edit
URL fixed.
It applies to DH60, DH82, and DH83
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Sounds fair enough to me. Really the only thing CASA could do in the circumstances.
Most of the rods in the fleet are almost at their calendar time limit anyway - although almost all would be nowhere near the hour limit.
Bit of a shame given the number of Tigers here and in NZ, that there is no approved local manufacturer for the rods and nuts on the list.
Another $120,000 lost by Aussie manufacturing (400 rods/nuts at say $300/rod) at a rough (hopeful) guess.
Most of the rods in the fleet are almost at their calendar time limit anyway - although almost all would be nowhere near the hour limit.
Bit of a shame given the number of Tigers here and in NZ, that there is no approved local manufacturer for the rods and nuts on the list.
Another $120,000 lost by Aussie manufacturing (400 rods/nuts at say $300/rod) at a rough (hopeful) guess.
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UK CAA Emergency AD
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As the UK CAA has now issued this AD, and the UK is the 'country of origin' of the tiger, does that make the CASA PAD obsolete? As in compliance with the CAA AD would now be mandatory?
ATSB Report released -
DH-82A VH-TSG, Near South Stradbroke Is, Dec 16 2013.
https://www.atsb.gov.au/publications...-2013-226.aspx
DH-82A VH-TSG, Near South Stradbroke Is, Dec 16 2013.
https://www.atsb.gov.au/publications...-2013-226.aspx
Very good ATSB report. Images of the wing breaking up in flight are pretty scary from a pilots perspective considering the terrible outcome.
Commercial aerobatic operations in an aeroplane built in 1939?
Commercial aerobatic operations in an aeroplane built in 1939?
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"Commercial aerobatic operations in an aeroplane built in 1939?"
Very relevant observation. Tiger Moth adventure flights seem to have been involved in a disproportionate number of fatal accidents in recent years.
As was mentioned above, it is unlikely they were designed to be used for commercial aerobatic operations some 75 years later.
Maybe it's time to stop using the "Limited" category as a loop hole for these types of operations and retire Tiger Moths to Private use only.
Very relevant observation. Tiger Moth adventure flights seem to have been involved in a disproportionate number of fatal accidents in recent years.
As was mentioned above, it is unlikely they were designed to be used for commercial aerobatic operations some 75 years later.
Maybe it's time to stop using the "Limited" category as a loop hole for these types of operations and retire Tiger Moths to Private use only.
Really? I can only think of two in recent years. Both from the same airfield. Tiger Moths don't need to be in the limited category to conduct commercial flights. A well maintained Tiger is as safe as most out there.
Local media covering themselves in glory - once again
. Note the headline vs the content and the ATSB report; of course Joe Public doesn't read further than the headline so the matter gets filed under pilot error in the public's minds.
No Cookies | Gold Coast Bulletin
. Note the headline vs the content and the ATSB report; of course Joe Public doesn't read further than the headline so the matter gets filed under pilot error in the public's minds.No Cookies | Gold Coast Bulletin
Well, here we go - again!
Stupid ill-informed statements made by both who made them above......
Do you both honestly think that all Tiger Moth aircraft were built in 1939 or whatever, WITHOUT some replacement of parts in the meantime..?????
As the owner and operator of a Tiger Moth aircraft 'built in 1942', I can assure you both that the ONLY part of this particular aircraft 'made in 1942' is the little brass plate saying so.......
During its 'life', ALL other components of the aircraft - like mainplanes, for example - have ALL been replaced more than a 'few' times - thanks to the Croydon Aircraft Company in NZ who manufactures excellent mainplanes to the original specifications or better.
Following this accident, I had to replace the lateral tie rods - again - they were 'done' about 18 months or so prior, as part of 'preventative' maintenance.
But they have now been 'done' again.
Due to the very nature of these and similar aircraft, I would wager 'London to a brick' that they are maintained by responsible owners to a very high standard as we acknowledge that we are only the 'custodians' of these historic aircraft, and that we will 'pass them on' when we 'pass on'.....
Back to your flight sims.....
No Cheers, Nope None at all!!
Stupid ill-informed statements made by both who made them above......
Do you both honestly think that all Tiger Moth aircraft were built in 1939 or whatever, WITHOUT some replacement of parts in the meantime..?????
As the owner and operator of a Tiger Moth aircraft 'built in 1942', I can assure you both that the ONLY part of this particular aircraft 'made in 1942' is the little brass plate saying so.......
During its 'life', ALL other components of the aircraft - like mainplanes, for example - have ALL been replaced more than a 'few' times - thanks to the Croydon Aircraft Company in NZ who manufactures excellent mainplanes to the original specifications or better.
Following this accident, I had to replace the lateral tie rods - again - they were 'done' about 18 months or so prior, as part of 'preventative' maintenance.
But they have now been 'done' again.
Due to the very nature of these and similar aircraft, I would wager 'London to a brick' that they are maintained by responsible owners to a very high standard as we acknowledge that we are only the 'custodians' of these historic aircraft, and that we will 'pass them on' when we 'pass on'.....
Back to your flight sims.....
No Cheers, Nope None at all!!
Originally Posted by Ex FSO Griffo
As the owner and operator of a Tiger Moth aircraft 'built in 1942', I can assure you both that the ONLY part of this particular aircraft 'made in 1942' is the little brass plate saying so.......
During its 'life', ALL other components of the aircraft - like mainplanes, for example - have ALL been replaced more than a 'few' times - thanks to the Croydon Aircraft Company in NZ who manufactures excellent mainplanes to the original specifications or better.
During its 'life', ALL other components of the aircraft - like mainplanes, for example - have ALL been replaced more than a 'few' times - thanks to the Croydon Aircraft Company in NZ who manufactures excellent mainplanes to the original specifications or better.
The wings fitted to the Tiger came from VH-ASB, with all but the lower left being continuously fitted from '86-2005 (no records available prior to '86), but -ASB's lower left wing - the one that ultimately failed mind you - was replaced with one of unknown origin and unknown vintage in 2001, with no record as to why. Those wings were them overhauled and fitted to -TSG in 2006, and from then on, had no mandatory inspection for over 1200 flight hours / 7 years - and this in an aircraft that is used for commercial aerobatics.....
Originally Posted by Ex FSO Griffo
Following this accident, I had to replace the lateral tie rods - again - they were 'done' about 18 months or so prior, as part of 'preventative' maintenance.
But they have now been 'done' again.
But they have now been 'done' again.
Originally Posted by Ex-FSO Griffo
Due to the very nature of these and similar aircraft, I would wager 'London to a brick' that they are maintained by responsible owners to a very high standard as we acknowledge that we are only the 'custodians' of these historic aircraft, and that we will 'pass them on' when we 'pass on'.....
Originally Posted by The ATSB
Furthermore, a review of the logbooks for VH-TSG and VH-ASB indicated that both aircraft had a history of numerous parts and components being transferred between multiple aircraft and being supplied with little or no documentation.
Thankyou for your comments Mr K,
but I did say 'responsible' owners etc etc.
And the comments made were described as being, generally against all (?) '1939' aircraft....
1. - "Commercial aerobatic operations in an aeroplane built in 1939? "
and,
2. - "Very relevant observation. Tiger Moth adventure flights seem to have been involved in a disproportionate number of fatal accidents in recent years.
As was mentioned above, it is unlikely they were designed to be used for commercial aerobatic operations some 75 years later.
Maybe it's time to stop using the "Limited" category as a loop hole for these types of operations and retire Tiger Moths to Private use only.
21st Jan 2016 16:30"
The biggest expense of owning a vintage aircraft like the Tiger Moth, is 'preventative maintenance'. There would be NO 'original' Tiger wings around these as the water based glues used in those days would have all failed by now, and the mainplanes would have been replaced.
This is only but ONE of the many items requiring attention as time goes by.
Nothing on the airframe is even close to being '75 years old'.....except ME!!
You are welcome to fly in this machine if ever you come to WA, it is excellently maintained by a well known LAME.
Cheers
but I did say 'responsible' owners etc etc.
And the comments made were described as being, generally against all (?) '1939' aircraft....
1. - "Commercial aerobatic operations in an aeroplane built in 1939? "
and,
2. - "Very relevant observation. Tiger Moth adventure flights seem to have been involved in a disproportionate number of fatal accidents in recent years.
As was mentioned above, it is unlikely they were designed to be used for commercial aerobatic operations some 75 years later.
Maybe it's time to stop using the "Limited" category as a loop hole for these types of operations and retire Tiger Moths to Private use only.
21st Jan 2016 16:30"
The biggest expense of owning a vintage aircraft like the Tiger Moth, is 'preventative maintenance'. There would be NO 'original' Tiger wings around these as the water based glues used in those days would have all failed by now, and the mainplanes would have been replaced.
This is only but ONE of the many items requiring attention as time goes by.
Nothing on the airframe is even close to being '75 years old'.....except ME!!
You are welcome to fly in this machine if ever you come to WA, it is excellently maintained by a well known LAME.
Cheers
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It's disheartening to see that a supposedly highly qualified engineer signed off on the manufacture of replacement tie rods, without going through all the engineering modifications/accident history associated with the design.
It's also disturbing to see that an authorised and reputedly competent engineering company, producing replacement aviation components, apparently took it upon themselves to replace the specified high-tensile carbon steel rod, with stainless steel rod of lower tensile strength and of variable specification, for the manufacture of the replacement tie rods.
It is even more disturbing that the threads installed on the replacement rods showed a wide variety of finish quality, with some threads appearing to be hand cut. Even some of the lathe-finished threads were of dubious finish.
In a high stress component such as the tie rods, surface finish is critical to prevent the initiation and propagation of cracking.
The fact that the tie rods in the accident aircraft were cracked through up to 60% of their thickness - and that this cracking was never found - is dreadfully disturbing, and virtually complete and utter negligence.
I can understand the engineering company suggesting a change to stainless steel because some previous tie rods produced, that had been in use, showed signs of serious corrosion.
However, to change the steel type without any reference to any aviation authority, and gaining official approval, shows a poor understanding of aviation engineering and processes - and even poorer supervision and quality control processes.
This accident shows up a pretty cavalier approach on the part of numerous personnel involved in the ownership, repair, and operating of this aircraft, towards maintenance, towards aviation replacements engineering, and towards record-keeping.
It does not reflect at all well on anyone associated with overseeing the Moth repair, the maintenance, the modifications, the quality control, and the adherence to strict and well-defined aviation principles, in a number of areas - and I personally feel the lawyers are bound to have a field day here, such are the major deficiencies discovered in the investigation.
It behoves anyone operating an aircraft well beyond its original projected lifespan, to ensure that engineering modification information and accident history is complete, up-to date, and properly recorded - and that maintenance and repair is of the highest level, to ensure any chance of disaster is reduced to the bare minimum.
To be additionally carrying out aerobatics in an aircraft well beyond any projected lifespan - and carrying members of the public as well - means that the requirements listed in the paragraph above must be above reproach.
The investigation has revealed such major shortfalls in the operation of the accident aircraft, that one could only properly describe it as a "cowboy outfit".
It's also disturbing to see that an authorised and reputedly competent engineering company, producing replacement aviation components, apparently took it upon themselves to replace the specified high-tensile carbon steel rod, with stainless steel rod of lower tensile strength and of variable specification, for the manufacture of the replacement tie rods.
It is even more disturbing that the threads installed on the replacement rods showed a wide variety of finish quality, with some threads appearing to be hand cut. Even some of the lathe-finished threads were of dubious finish.
In a high stress component such as the tie rods, surface finish is critical to prevent the initiation and propagation of cracking.
The fact that the tie rods in the accident aircraft were cracked through up to 60% of their thickness - and that this cracking was never found - is dreadfully disturbing, and virtually complete and utter negligence.
I can understand the engineering company suggesting a change to stainless steel because some previous tie rods produced, that had been in use, showed signs of serious corrosion.
However, to change the steel type without any reference to any aviation authority, and gaining official approval, shows a poor understanding of aviation engineering and processes - and even poorer supervision and quality control processes.
This accident shows up a pretty cavalier approach on the part of numerous personnel involved in the ownership, repair, and operating of this aircraft, towards maintenance, towards aviation replacements engineering, and towards record-keeping.
It does not reflect at all well on anyone associated with overseeing the Moth repair, the maintenance, the modifications, the quality control, and the adherence to strict and well-defined aviation principles, in a number of areas - and I personally feel the lawyers are bound to have a field day here, such are the major deficiencies discovered in the investigation.
It behoves anyone operating an aircraft well beyond its original projected lifespan, to ensure that engineering modification information and accident history is complete, up-to date, and properly recorded - and that maintenance and repair is of the highest level, to ensure any chance of disaster is reduced to the bare minimum.
To be additionally carrying out aerobatics in an aircraft well beyond any projected lifespan - and carrying members of the public as well - means that the requirements listed in the paragraph above must be above reproach.
The investigation has revealed such major shortfalls in the operation of the accident aircraft, that one could only properly describe it as a "cowboy outfit".