Getting the shaft.

[Lu Zuckerman]

This is a problem for the engineering types out there:

On the EH-101 many accessories are driven off of a separate gearbox that is mounted in front of the main transmission. This gearbox is driven by two redundant drive shafts that are of thin wall construction. During normal operation there is minimal torsional stress on the drive shafts. Here is the problem. The rotor brake is also mounted on this gearbox as opposed to being mounted on the main transmission. During the preparation of the FMEAs it was determined that there was a possibility of the rotorbrake dragging to the point of generating sufficient heat to start a fire. It was also determined that the rotor brake could come on hard with a solid lock-up of the disc. Both of these comments in the FMEAs were purged as the management of the R&M group arbitrarily determined that there would be no catastrophic failures on the EH-101. Well it is obvious that he was wrong as at least two EH-101s have crashed due to fire in the area of the rotorbrake and the possibility of a hard lock-up is waiting in the wings. I had indicated in the FMEA that if the rotorbrake had a hard lock-up the kinetic energy of the spinning rotor which was still being driven by two (or three) engines would build up sufficient torsional stresses as to twist the shafts to the point of separation. Thus, causing loss of a hydraulic system and some electrical generation capability, which would jeopardize the reliability, and safety of the helicopter. I was told that the shafts would not fail due to the gear reduction of the main transmission. If one end of the system is stopped and the other end of the system is still rotating at speed the only thing between the main transmission and the rotorbrake were the two thin wall shafts. What do you think? Will the shafts fail or will they not fail.

[heedm]

Lu, it's impossible to answer your question authoritatively based on what you've presented. It is possible that a brake at one end of a shaft that is driven or has rotational kinetic energy from the other end could cause the shaft to fail, but that is only one possibility.

To simplify a complex matter, for anything to break, the brake must be able to exert a torque that is greater than the weakest link. For your proposition to be valid, the brake must be strong enough, the energy must be high enough, and the shafts must be the weakest link in the chain.

From what I understand, the rotor brake of the EH101 has been changed during development. Is your information current?

[Hookherder]

Lu,

That design concept strikes a distressingly similar comparison to the CH-47 accessory gearbox and quill shaft setup of the earlier models. Are we reinventing the wheel as we go?

Quill shaft failures were not to be considered if you wished to fly Chinooks without developing a drinking habit.

Failure of the only drive to the accessory gearbox could lead to an interestign situation....no flight control hydraulics, utility system hydraulics, and a loss of electrical power beyond what the battery would produce.

That would have made for an interesting APU start procedure in cloud at night.

[Lu Zuckerman]

To: heedm and Hookherder

It was my contention that the drive shafts were the weakest link and would fail if enough torsion were applied. During shut down the rotorbrake could bring the rotor to a stop in just a few seconds with significant heat build up and rejection but in this case the kinetic energy was decreasing at a constant rate so that any torsion applied to the shafts would also be constantly decreasing. However in the condition I described there would be two or three T-700 engines or the RR replacement engines driving the rotor and the accessory gearbox and there would be an even greater heat build up and more heat to be rejected causing the brake to clamp even harder. I believe there is a pressure release system that would allow the expanding fluid to vent but I believe by that time the shafts would have failed or possibly there would also be a fire.

Regarding the CH-47 quill shaft failure the EH-101 has redundant shafts to cater for a failure of one shaft. Regarding the change to the rotorbrake I believe that was a change in the electrical circuitry and not the relocation of the brake to the transmission. I must also state that my statements above were based on knowledge obtained in or around 1987 when the system was being designed and therefore my question relates to my findings in the FMEA.

[ 14 February 2002: Message edited by: Lu Zuckerman ]</p>

[Weight and Balance]

Lu said:

"It was my contention that the drive shafts were the weakest link and would fail if enough torsion were applied."

Absolutely right. Twist anything hard enough and it will break. (Fudd's axiom, 43rd variation).

Heedm said:

"It is possible that a brake at one end of a shaft that is driven or has rotational kinetic energy from the other end could cause the shaft to fail, but that is only one possibility."

Absolutely right. This is a dynamic situation with several possible outcomes. If I was asked to properly investigate the possibilities, I would need to know:

- what is the deceleration rate of the rotating assembly after the assumed brake failure mode?. .- what inertia is in the rotating mass, including the inertia of the driven accessories(and possible "psuedo-inertia" due to EMF and hydraulic goings-on as the accesories are slowed down)?. .- what are the torsional stiffnesses of all the rotating components involved?

Then it would be simple to predict a time history of omega-dot and omega-double dot and thus torsional loads on the shafts in question, and see if Fudd applies in this case. Well, simple, way back when I had just got out of school and still knew all that stuff.

Lu said:. ."the EH-101 has redundant shafts to cater for a failure of one shaft."

I'll assume that the dual shaft resulted from an FMEA that predicted a single shaft failure due to problems within that one shaft: manufacturing defect, maintenance error, etc. If I understand the connectivity here, the inertia effect of a brake failure could effect both shafts at the same time, and some other mitigation would be required to drive down the RPN (or whatever it's called these days) of this failure to an acceptable level.

Any disgruntled ex-Westlanders out there care to share the details of the FMEA with us? We promise not to tell anybody where the info came from.

[ 15 February 2002: Message edited by: Weight and Balance ]</p>

[Lu Zuckerman]

To: Weight and Balance

The FMEA was written against the design that had already been cast in concrete and not the system being designed because of a failure predicted in the FMEA.

Regarding Westland having any knowledge of this specific FMEA I would doubt seriously if they had a clue about this FMEA or for that matter any FMEAs that were written by Agusta. The FMEAs written by both Agusta and Westland were supposed to interface with each other with this being done using some type of a computer conversion program. Agusta and Westland used different computer systems that could not talk to each other and consequently Westland and Agusta had no knowledge of the FMEAs being written by the other company. At some point paper copies may have been transferred from one firm to another but to my knowledge, the conversion program that allowed the computers to talk to each other was never developed. Another point that must be understood is that the two companies each had specific design responsibilities and FMEAs represented the elements that were being designed by each company. The manager of the Agusta R&M department in a pique of anger decided to remove all of the catastrophic failures from the FMEAs and I can only assume that Westland did not follow suit. The failures that caused the crashes of the EH-101 were originally predicted in the original FMEAs but they were removed as indicated above.

[ 15 February 2002: Message edited by: Lu Zuckerman ]</p>

[rigid_rotor]

If you knew the latest rotor brake design on the EH101 and knew why the last crash occured you would not have started this thread unless you just wanted to stir things up that were inconsequential.

Apply torsion to a shaft and it will break (eventually).

Wait long enough and zuckerman will bleat on about FMEA conducted before colour TV was available.

Get up to date please before making statements about a current ac that you were involved in long ago.

I guess in your reply you will go about how long you worked on the 101 blah blah blah. Name a few names blah blah. But its ALL out of date with regard 101.

You have a lot to add to the forum about your current work but please stay up to date or back off.

[helmet fire]

Lu:

You said: &gt;&gt;The manager of the Agusta R&M department in a pique of anger decided to remove all of the catastrophic failures from the FMEAs and I can only assume that Westland did not follow suit. The failures that caused the crashes of the EH-101 were originally predicted in the original FMEAs but they were removed as indicated above.&lt;&lt;

. .From what I gather you appear to be saying that the crashes of the EH-101 were predicted, but that an Augusta manager removed the predictions purely out of anger, and failed to tell Westland. Lu, you sure do have the biggest balls. What a call. You were not even alledging it, you were stating it!

From your previous posts you have claimed that you have often been engaged as an expert witness, so why didn't the families of those who lost their lives in the crashes pay your exhorbitant fee to tell this story? Don't you have a moral obligation to contact them and tell them that you know about the crash causes?

I imagine that you may yet have to be an expert witness in this case - in your own defence against the litigation that should follow your incredible claims. <img src="eek.gif" border="0">

As for the actual theory of shaft breakage, etc, it was well answered above by Weight & Balance, but being a reliability engineer, you already knew that answer, for it is your bread and butter, n'est pas?

By the way, did you ever ring the US Army (being a patriotic American) and warn them of their lack of night time stealth whilst flying helicopters at night in rarified desert air?

These huge calls you make are my reason for reading Pprune. Keep em comming!!

:)

Edited to ammend the name of W & B

[ 15 February 2002: Message edited by: helmet fire ]</p>

[Lu Zuckerman]

To: Helmet Fire

I quote “From what I gather you appear to be saying that the crashes of the EH-101 were predicted, but that an Augusta manager removed the predictions purely out of anger, and failed to tell Westland. Lu, you sure do have the biggest balls. What a call. You were not even alleging it, you were stating it”.

I was supervising the preparation of the FMEAs on the EH-101 using a computerized reporting form which I developed for the A-129 Mangusta. While I was doing that, Westland was developing a similar computerized format. The problem was that the two companies were using computers that could not interface with each other because of programming and server differences. It was the intention of Agusta and Westland to develop a program that would allow this interface to take place. I do not think this program was ever developed so both companies were blind to what the other was doing.

I attended a meeting at EHI headquarters in London to discuss this program along with manpower allocations and work sharing. Agusta had five R&M engineers only two of who spoke English and none had any formal training in R&M. That was the reason for my being there. Develop the program and instruct the employees how to perform the analysis as well as teaching the system to a young lady that had minimal English skills on how to enter the information into the computer.

At the meeting I found out that Westland was reducing their staff to a very low level (possibly 6-7 men). As an example the Apache program had 38+ R&M engineers on staff and Agusta had 5 men and Westland had 6-7 men and they were committing to a level of effort that would take 60-70 R&M engineers not including about 10 safety engineers. I sat there for a while and finally spoke up asking if I could say something. I got up and closed the door and started to raise my voice telling both managers that they did not have enough personnel on staff to accomplish 1/10th of the work they were both proposing. I told them that to make that kind of commitment they would jeopardize both companies in the eyes of the Royal Navy and the Italian Navy and the certification authorities. Both managers were shaken by my attack, as that is just not done in civilized Europe.

When I got back the manager told the engineers that I was supervising not to talk to me. I didn’t mind as I was making a ton of money and I had no responsibility. I just loafed around for a month and then the manager told the men to go back into the computer and remove all catastrophic failures from the FMEAs. It appeared that I had attacked his MACHISMO and this was his revenge because I was very adamant that catastrophic failures be included in order to drive the design.

Since Westland and Agusta computers could not talk to each other Westland was unaware of what had transpired at Agusta.

I wish I had bigger balls (as well as the attached equipment) but that is another story. I may come off in these threads as an idiot (according to Nick Lappos) but when I am being paid to do a job my main purpose is to protect the company that is paying my salary. I have found out through experience that some companies do not want to be saved. What they want to save is money and to that end they deliver second rate equipment. IMHO

Regarding the expert witness comment I was contacted by the Royal Navy and asked if I would participate in an investigation. I agreed but nothing came of it.

[ 16 February 2002: Message edited by: Lu Zuckerman ]</p>

[sling load]

Lu,

I this, I that, I did this, I did that, blah blah... as rigid rotor says, but as soon as something is wrong, its they did this, they did that, machines designed by humans are never perfect, only you are Lu.

[Lu Zuckerman]

To: sling load

Would you rather my comments be made in the third person? How else could Mr. Zuckerman respond to comments without using the personal pronoun I? His comments are in the first person because it allows him to fully describe what led up to the removal of the catastrophic failures from the FMEAs.

[helmet fire]

Lu,

Another huge call Lu. Dont wish for bigger balls than those you have already shown, you'll need a wheelbarrow! :) . .I cannot believe that you write this stuff without fear of legal retribution.

You said : &gt;&gt;none [of the engineers] had any formal training in R&M. That was the reason for my being there. Develop the program and instruct the employees how to perform the analysis...&lt;&lt;

Would you not then say that, as you were the only one formally trained on R&M, and that as you were paid to develop and teach a program whose failure may have lead to the accidents, that perhaps there is some responsibility for you? Or do you believe your "attack" (as you put it) absolves you?

Your post is an incredible story of insider knowledge that may have saved the lives of many people - if only Augusta had listened - if only you had taken the information to some one who could have acted upon it. I ask again, why dont you contact the families and offer to help? Does any one out there know how Lu can contact them?

BTW: what is R&M and FMEAs?

Edited to add FMEAs!

[ 16 February 2002: Message edited by: helmet fire ]</p>

[Lu Zuckerman]

To: helmet fire

I quote “Would you not then say that, as you were the only one formally trained on R&M, and that as you were paid to develop and teach a program whose failure may have lead to the accidents, that perhaps there is some responsibility for you? Or do you believe your "attack" (as you put it) absolves you”?

Response:

The manager of the department was well versed in R&M and I will admit from knowledge of the specs covering R&M he probably knew more than I did. He however did not have a clue as to how to implement the program.

Here is my personal philosophy regarding my effort in being a consultant in R&M. I tell my client that there are wolves, there are sheep and there are sheep dogs that protect the sheep from the wolves. I am the sheep dog and the client is the sheep. The customer and the certification authorities are the wolves as are the subcontractors for the client. In making my “attack” as you put it I was trying to impress on my client (Agusta) and Westland that they were committing to a level of effort that they were incapable of sustaining. Making promises to the customer and setting delivery dates for that level of work and not being able to meet it was a death sentence as Agusta and Westland would have to pay a significant penalty. This penalty would have negated any profit the two companies would have made on their R&M effort. In effect I was protecting them from the wolves as well as from themselves.

When I left Agusta I went to work for their hydraulic system supplier and they became the sheep and Agusta was the wolf.

Here is another fact regarding culpability in the event of a lawsuit. As an R&M engineer I could be held liable along with other members of the company including management and engineering if I knowingly covered up a design flaw that eventually led to the loss of an aircraft and its’ passengers and crew. That is why I get so vocal in making my point of view known to everybody.

Here is another point of law. The Warsaw and Montreal conventions set a limit on the amount that can be claimed in a lawsuit (Flying Layer correct me if I am wrong). However if it can be proved that the company intentionally covered up a design flaw or concealed specific information then the amount of recovery is unlimited. That is why I try to impress upon my clients what is right and what is wrong.

If some lawyer wants to pick up on that then so be it. What I say is the truth.

Oh, by the way, R&M= Reliability and Maintainability and FMEA = Failure Modes Effects Analysis or FMECA = Failure Modes Effects Criticality Analysis.

[ 16 February 2002: Message edited by: Lu Zuckerman ]</p>

[heedm]

Lu, thanks for spelling out the acronyms, I was getting a little bit too imaginative.

. .This is all coffee table rumour, but I heard that the engineers in Italy may be undergoing legal scrutiny of some sort because of past failures of the EH101. Can anyone confirm this?

[Lu Zuckerman]

To:helmet fire

Here are two examples of how much influence I had in changing the minds of Agusta engineers.

1) Several years before my arrival at Agusta they had hired LTV to set up and run the R&M department and the Product Support department during the development of the A-109. LTV had about 30 men on staff and every time they tried to implement any new ideas the Agusta personnel stood in their way. They made it so difficult for the LTV staff that they cancelled the contract and returned to the United States. When I arrived at Agusta to make my presentation relative to what I was proposing they treated me as a visiting dignitary However, shortly after my starting the job I could see that any attempt to change things or make suggestions I realized it was an attack on their collective machismo. It was not that I was treated badly as I was not but they just would not listen.

2) The last six months of my contract I was assigned to work with the director to get the Engineering department and the Product Support department managers to talk to each other. During the development of the A-109 there were three or four key people on the design team. There was a lot of bad blood between them and as the program evolved and they entered into the A-101 program the animosity got worse. Flash forward 10-12 years there had been at least two turnovers of management in engineering and three in the product support and even though the new department heads had minimal involvement with the A-109 design and the A-101 the bad blood still existed. I acted as an ombudsman trying to get them together as full cooperation was required on the EH-101 and A-129 programs. When I left at the completion of my contract they were still not talking to each other.

[CyclicRick]

If it's any consolation to Lu, a friend of mine flys a 109E. According to him the bloody thing is a liability it spends 85% of it's time with a specially flown in Italian mechanic somewhere inside it trying to bluff his way out of "known" technical problems which suddenly occur. Beautiful when it flys, if it flys.