EH101 crash
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The EH101 was not designed to lift off after a water landing be it from a ditching or a purposeful landing on the water. Once down it stays down. In addition the twin engine capability of this 3 engined hippo is non existent!
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TC
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TC
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To: Thomas Coupling
During the design stage it was considered that the helicopter at some time would intentionally land on the water and take off again. That is why I made the request for the valves in the vent system. By your argument it would be strange that a helicopter capable of flight be allowed to remain on the water if it were ditched for a condition that was repairable while on the water or if the pilots put it on the water to effect a rescue or some other reason.
Under the scenario you stated how do they get the helicopter back to base.
Regarding two engine operation, The Italian Navy like the Royal Navy did not want the helicopter and to top that, they saw no reason to have a third engine.
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The Cat
[This message has been edited by Lu Zuckerman (edited 20 November 2000).]
[This message has been edited by Lu Zuckerman (edited 20 November 2000).]
[This message has been edited by Lu Zuckerman (edited 20 November 2000).]
During the design stage it was considered that the helicopter at some time would intentionally land on the water and take off again. That is why I made the request for the valves in the vent system. By your argument it would be strange that a helicopter capable of flight be allowed to remain on the water if it were ditched for a condition that was repairable while on the water or if the pilots put it on the water to effect a rescue or some other reason.
Under the scenario you stated how do they get the helicopter back to base.
Regarding two engine operation, The Italian Navy like the Royal Navy did not want the helicopter and to top that, they saw no reason to have a third engine.
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The Cat
[This message has been edited by Lu Zuckerman (edited 20 November 2000).]
[This message has been edited by Lu Zuckerman (edited 20 November 2000).]
[This message has been edited by Lu Zuckerman (edited 20 November 2000).]
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I posted this on several other threads:
posted 25 November 2000 13:07
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During the design of the EH-101 I brought a potential problem to the attention of the design engineers for the rotorhead and the flight control systems.
The rotor head on the EH-101 uses elastomeric bearings that allow pitch, flap and lead/lag. In the design stage it was not decided which way the bearings were to be installed. The original concept was to install the bearings so that they operated in flight in and about the neutral position which would minimize the stresses in the bearing. The other concept was to install the bearings in the relaxed state while in low pitch thus increasing the stresses when the bearings were in high pitch while in flight. At the time of my involvement they were going with the former as opposed to the latter.
In this situation when the rotor was stopped
and folded along with the tail pylon being folded the hydraulics were still on. With the hydraulics off, the residual torsion in the elastomeric bearings would tend to relax and try to return to the neutral position.
However, with the tail folded these forces would be locked in the system which would place the entire flight control system under a compressive or tensile load ( I can't remember which).
In either case, if the system had to be maintained, requiring a disconnect of the system a control rod could injure the tech and cause a lot of damage to his/her hands and/or face.
I left the program before a final decision had been made. In any case, watch out.
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The Cat
posted 25 November 2000 13:07
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During the design of the EH-101 I brought a potential problem to the attention of the design engineers for the rotorhead and the flight control systems.
The rotor head on the EH-101 uses elastomeric bearings that allow pitch, flap and lead/lag. In the design stage it was not decided which way the bearings were to be installed. The original concept was to install the bearings so that they operated in flight in and about the neutral position which would minimize the stresses in the bearing. The other concept was to install the bearings in the relaxed state while in low pitch thus increasing the stresses when the bearings were in high pitch while in flight. At the time of my involvement they were going with the former as opposed to the latter.
In this situation when the rotor was stopped
and folded along with the tail pylon being folded the hydraulics were still on. With the hydraulics off, the residual torsion in the elastomeric bearings would tend to relax and try to return to the neutral position.
However, with the tail folded these forces would be locked in the system which would place the entire flight control system under a compressive or tensile load ( I can't remember which).
In either case, if the system had to be maintained, requiring a disconnect of the system a control rod could injure the tech and cause a lot of damage to his/her hands and/or face.
I left the program before a final decision had been made. In any case, watch out.
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The Cat
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Lu: thanks for your CV...very impressive indeed keep up with the inputs. It would be nice though to hear some good news about some helo design out there!! There must be a success story somewhere!!
My comments regarding the water-borne capabilities of the EH 101 are based on briefings by a MOD company who are now in partnership with an overseas company based in a country famous for its pizzas!!
They declared that the aircraft did not have the lift capability of launching from the sea in anything other than sea state 1 with all systems operating. From experience the S61 I flew onto lakes, 5 times a day many years ago was taped up and assessed watertight even then, it leaked about a half ton of water every minute it remained on the water!! This was when the surface was ripple free!!
The chances of a non existant sea state in any of the envisaged operating areas of the 101, together with the fact that the a/c did not have a 'boat hull' and in addition the possibility of it being there because a system had failed gave rise to their statement that this a/c was not intended to fly away from a sea landing.
Add to that the teaching that a helo should not be flown off the water after a 'surprise' landing due to the inability to confirm the integrity of the tail rotor and sea water ingress to its electrics...reinforced this opinion.
Your other point regarding ..."how is the a/c recovered..."
The same way we always recovered them:
lifting gear onto a support vessel's deck, or towing ashore (if nearby)but this invariably led to the loss of the craft due to swamping!! Good to watch though!!
Take care..
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TC
My comments regarding the water-borne capabilities of the EH 101 are based on briefings by a MOD company who are now in partnership with an overseas company based in a country famous for its pizzas!!
They declared that the aircraft did not have the lift capability of launching from the sea in anything other than sea state 1 with all systems operating. From experience the S61 I flew onto lakes, 5 times a day many years ago was taped up and assessed watertight even then, it leaked about a half ton of water every minute it remained on the water!! This was when the surface was ripple free!!
The chances of a non existant sea state in any of the envisaged operating areas of the 101, together with the fact that the a/c did not have a 'boat hull' and in addition the possibility of it being there because a system had failed gave rise to their statement that this a/c was not intended to fly away from a sea landing.
Add to that the teaching that a helo should not be flown off the water after a 'surprise' landing due to the inability to confirm the integrity of the tail rotor and sea water ingress to its electrics...reinforced this opinion.
Your other point regarding ..."how is the a/c recovered..."
The same way we always recovered them:
lifting gear onto a support vessel's deck, or towing ashore (if nearby)but this invariably led to the loss of the craft due to swamping!! Good to watch though!!
Take care..
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TC
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T-C (et al):
Don't you see this as an example of the K.I.S.S. arguement. - Simplification of systems. Less is more. Too many chefs (engines) spoils the broth. One reliable engine is better than two unreliable etc
(BTW the military capability of 225! R44's has got to be superior to 1 EH101, and you can keep 225 R44 flying with 12 ground people! Ok so for the military lets build in some redundancy and call it 100 people! how many ground people to maintain 1 EH101?)
Don't you see this as an example of the K.I.S.S. arguement. - Simplification of systems. Less is more. Too many chefs (engines) spoils the broth. One reliable engine is better than two unreliable etc
(BTW the military capability of 225! R44's has got to be superior to 1 EH101, and you can keep 225 R44 flying with 12 ground people! Ok so for the military lets build in some redundancy and call it 100 people! how many ground people to maintain 1 EH101?)
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The thread on the miltary board relates to the loss of the first Italian prototype that suffered a fatal accident after a rotor brake fire caused the primary flight controls to fail ( some talk of composite control rods ).
The story is that the rerofit to prevent recurrance of this was incorrectly installed on the latest accident aircraft and was found defective on others of the fleet. I think a lot of Canadian Miltary pilots might be thanking Chretien for his prevarication now. The Canadian miltary would have been "proving" their first aircraft by now if it had not been for the liberals delay of the program.
The story is that the rerofit to prevent recurrance of this was incorrectly installed on the latest accident aircraft and was found defective on others of the fleet. I think a lot of Canadian Miltary pilots might be thanking Chretien for his prevarication now. The Canadian miltary would have been "proving" their first aircraft by now if it had not been for the liberals delay of the program.
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101 robbies for 1 Merlin , interesting concept . Only problem ( opportunity) is finding 101 pilots. ( but as this is the pilots network i guess that is a benefit).
I think the r22 might be a bit shy on range and the autohover and load carrying ability may be a problem. What we need is a side by side comparison . I have now doubt that 101 robbies would be cheaper than one Merlin even if you chucked them out when they reach TBO.
I think the r22 might be a bit shy on range and the autohover and load carrying ability may be a problem. What we need is a side by side comparison . I have now doubt that 101 robbies would be cheaper than one Merlin even if you chucked them out when they reach TBO.
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So here we go then, another piece of kit for the Forces that now they decide that don't want........! Take the lid off boys and look in side, you might just learn a thing or two about the future of helicopters.
Being very close to the operational side of this aircraft I believe the only area for concern is the prime contractor Lockheed. They are a complete bunch of idiots and could organise a helicopter program if their professional lives depended on it!!
We have told industry many times about the problems with the Merlin and assumed that the prime contractor would do something about but we were wrong. Talking to contacts in EHI it appears that the information flowed back to the experts at Westlands is highly censored and all the major problems are being stored up until the MoD give LMA some more money to fix them!!!
Why don't LMA walk away from the contract and let us deal with Westland direct? Since the crash Westlands have bent over backwards to help with the investigation, LMA have been no where to be seen, thanks chaps you take all the money and let Westlands take all the crap!!
On the subject of engines, more the better I say!!
Being very close to the operational side of this aircraft I believe the only area for concern is the prime contractor Lockheed. They are a complete bunch of idiots and could organise a helicopter program if their professional lives depended on it!!
We have told industry many times about the problems with the Merlin and assumed that the prime contractor would do something about but we were wrong. Talking to contacts in EHI it appears that the information flowed back to the experts at Westlands is highly censored and all the major problems are being stored up until the MoD give LMA some more money to fix them!!!
Why don't LMA walk away from the contract and let us deal with Westland direct? Since the crash Westlands have bent over backwards to help with the investigation, LMA have been no where to be seen, thanks chaps you take all the money and let Westlands take all the crap!!
On the subject of engines, more the better I say!!
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If I am correct Lockheed Martin was awarded the contract to design and integrate the electronics suite for the Merlin. IBM had a similar contract with Sikorsky but neither company had anything to do with the design of the helicopters. They are the program managers but should not have much say so relative to airframe problems. But then, I started this post by saying if I am correct.
As far as getting a lot of crap, Westland by virtue of the consortium contract with Agusta was responsible for the Merlin and Agusta was responsible for the Italian Navy version as well as any civilian derivitives But the crap should be shared, as Agusta, designed the system.
As I stated in several posts above the rotorbrake failure among many others was predicted to happen but all references to catastrophic failures were removed from the FMEAs.
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The Cat
[This message has been edited by Lu Zuckerman (edited 29 November 2000).]
As far as getting a lot of crap, Westland by virtue of the consortium contract with Agusta was responsible for the Merlin and Agusta was responsible for the Italian Navy version as well as any civilian derivitives But the crap should be shared, as Agusta, designed the system.
As I stated in several posts above the rotorbrake failure among many others was predicted to happen but all references to catastrophic failures were removed from the FMEAs.
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The Cat
[This message has been edited by Lu Zuckerman (edited 29 November 2000).]
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Lu, I believe that you are correct but one rumour that I have heard is that the crash was cause by some incompatible software being fitted to the aircraft becuase LMA hadn't paid for the up to date kit. Is this not a programme management issue?
What parts of the electronics suite or system did LMA design? Was it the Flight Management System?
What parts of the electronics suite or system did LMA design? Was it the Flight Management System?
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To: Chin Chin
When I worked on the program Lockheed had not merged with Martin and not being directly connected with the electronics system or, supporting software I can't say.
Regarding my comment above I would now say that Lockheed Martin is responsible for the problem assuming what you indicated is proved to be correct.
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The Cat
When I worked on the program Lockheed had not merged with Martin and not being directly connected with the electronics system or, supporting software I can't say.
Regarding my comment above I would now say that Lockheed Martin is responsible for the problem assuming what you indicated is proved to be correct.
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The Cat
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To: Chin Chin
As a consultant, I supervised the preparation of the FMEAs. My main function in preparing the FMEAs was on the dynamic system and the power train. However I did not work on the front gear box.
The individual that worked on the front gear box identified several potential problems relating to circuitry defects and internal leakage both of which would cause the application of the rotor brake in flight. Jacking that failure up a notch or two it was apparent that they were catastrophic failures. In my investigation of the potential problems I determined that it was possible for the brake to come on hard and as a result the two thin walled drive shafts would be severely damaged enough to separate losing all of the services on the front gear box as well as causing a significant overheat condition. Those catastrophic failures among all of the others were eliminated from the FMEAs on the whim of the department manager.
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The Cat
As a consultant, I supervised the preparation of the FMEAs. My main function in preparing the FMEAs was on the dynamic system and the power train. However I did not work on the front gear box.
The individual that worked on the front gear box identified several potential problems relating to circuitry defects and internal leakage both of which would cause the application of the rotor brake in flight. Jacking that failure up a notch or two it was apparent that they were catastrophic failures. In my investigation of the potential problems I determined that it was possible for the brake to come on hard and as a result the two thin walled drive shafts would be severely damaged enough to separate losing all of the services on the front gear box as well as causing a significant overheat condition. Those catastrophic failures among all of the others were eliminated from the FMEAs on the whim of the department manager.
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The Cat