Flight Dynamics: The Swashplate and Phase-angle
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Frank Robinson,
Sort out the rotor head and blades of your helicopters as you must have made a pile of dosh, enough to put right the Achilles Heel of your popular helicopter.
Almost if not all accidents with your helicoptres are due in one way or the other with the awful rotor head and blades where pilot error was not the cause.
You have the means of rectifying and making good. So why do you continue to accept all the hassel of +bad publicity.
Does Frank read this thread? Does anyone know?
Sort out the rotor head and blades of your helicopters as you must have made a pile of dosh, enough to put right the Achilles Heel of your popular helicopter.
Almost if not all accidents with your helicoptres are due in one way or the other with the awful rotor head and blades where pilot error was not the cause.
You have the means of rectifying and making good. So why do you continue to accept all the hassel of +bad publicity.
Does Frank read this thread? Does anyone know?
Senis Semper Fidelis
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HT,
I like many others have tried to read up on as many PPL(H) accidents as possible, for no other reason as to be able to glean from those reports anything that may help me be a better pilot as far as I can in the private flying world.
But when you ready of the many R22 accidents it seems there is a mantra of comments from Robinson's that always it seems 99% of the time the Pilot is fingered for the accident and this is nearly always backed up by the Robinsin Company, thats fine because the FAA and the CAA here in the UK are seen to be impartial when collating information on any incident, but when the Robbie guys get involved the Pilot is "numero uno",... BUT this cannot always be so.
With the scant information that we are starting to see regarding the blades and the heads especially with these cracks, I feel that some body like the FAA or the CAA should really now do their job and really go in hard to find out why we are seeing this many Rotor problems, that will KILL pilots if left unchecked.
Or will it be left alone,
Peter R-B
I like many others have tried to read up on as many PPL(H) accidents as possible, for no other reason as to be able to glean from those reports anything that may help me be a better pilot as far as I can in the private flying world.
But when you ready of the many R22 accidents it seems there is a mantra of comments from Robinson's that always it seems 99% of the time the Pilot is fingered for the accident and this is nearly always backed up by the Robinsin Company, thats fine because the FAA and the CAA here in the UK are seen to be impartial when collating information on any incident, but when the Robbie guys get involved the Pilot is "numero uno",... BUT this cannot always be so.
With the scant information that we are starting to see regarding the blades and the heads especially with these cracks, I feel that some body like the FAA or the CAA should really now do their job and really go in hard to find out why we are seeing this many Rotor problems, that will KILL pilots if left unchecked.
Or will it be left alone,
Peter R-B
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Does Frank read this thread? Does anyone know?
PW
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Finger pointing is the name of the game.
To: Vfrpilotpb
In April of 1996 I sent an unsolicited report to the NTSB dealing with the R-22 Rotorhead and the rigging procedures which if followed by the mechanic could lead to problems. About a month later Mr. Ron Price contacted me. He was the principal investigator on the loss of control accidents that were discussed in detail in the NTSB report on loss of control. Mr. Price told me that the NTSB strongly recommended to the FAA that the R-22 certification be rescinded. The FAA would not do so and in turn contracted with Georgia Tech to determine the reasons for so many accidents. The investigation was cut short and Robinson added to section 4 of the POH the reasons for the accidents and how to avoid them. This material was never officially entered into the POH and signed off by the FAA so it really had no strength in forcing the operators to comply.
Mr. Price stated to this writer that the next time the R-22 had a loss of control accident he personally would shove it down the throats of the FAA and force them to ground the R-22. Since that time the R-22 has experienced about seven loss of control accidents one of which occurred in the UK and another in Ireland. And all were pilot error.
With the scant information that we are starting to see regarding the blades and the heads especially with these cracks, I feel that some body like the FAA or the CAA should really now do their job and really go in hard to find out why we are seeing this many Rotor problems, that will KILL pilots if left unchecked
Mr. Price stated to this writer that the next time the R-22 had a loss of control accident he personally would shove it down the throats of the FAA and force them to ground the R-22. Since that time the R-22 has experienced about seven loss of control accidents one of which occurred in the UK and another in Ireland. And all were pilot error.
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So what you really saying
Lu
Are you really saying the "death Egg" should not be in service.
Correct me if i am wrong ?
MD
Are you really saying the "death Egg" should not be in service.
Correct me if i am wrong ?
MD
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History and lessons learned.
To: MD900 Explorer
When I first joined PPRuNe in September of 2000 my very first post had to do with the certification of the R-22 and by definition the R-44. My reason for joining PPRuNe was that I had raised the same question on Just Helicopters and I was booed and jeered off of that forum mainly from Robbie lovers and partly by the jerks that frequent that forum. To my surprise I got the same response from members of this forum. Many helicopter pilots and those in training have a vested interest in the Robinson helicopters and refuse to admit that there might be a problem.
The question I posed about the ability of the Robinson design to achieve certification if it were proposed to the FAA as a new design. The question stems from the fact that there are several non-compliances with the requirements of AC-27-1 dated 8-29-85 and CFR 14 Part 27 (Airworthiness Standards: Normal Category Rotorcraft Revised 1-1-94.
Add to this, the FAA has stated that flying out of trim and sideslipping would result in possible mast bumping and rotor incursion due to the flapping extremes on the rotor system when exposed to these maneuvers. To gain certification a helicopter must be flown in a 90-degree sideslip at .68 VNE both left and right and, it must be flown 10-degrees out of trim at the same speed yet the FAA has placed a “restriction” on these maneuvers. If Frank Robinson presented his helicopter to the FAA for certification and he told them of the non-compliance’s with the regs. And that his helicopter could not be sideslipped or flown out of trim they would refuse certification (IMHO)
Add the rigging procedures, which are totally different from any other helicopter. The procedures place the mechanic in a bad position in trying to rectify the written procedures with what he knows to be correct.
I would strongly suggest that those members of this forum that fly Robinson products read the rigging procedures and if they don’t understand them ask a mechanic to explain what they mean and the discrepancies in the procedures.
When I first joined PPRuNe in September of 2000 my very first post had to do with the certification of the R-22 and by definition the R-44. My reason for joining PPRuNe was that I had raised the same question on Just Helicopters and I was booed and jeered off of that forum mainly from Robbie lovers and partly by the jerks that frequent that forum. To my surprise I got the same response from members of this forum. Many helicopter pilots and those in training have a vested interest in the Robinson helicopters and refuse to admit that there might be a problem.
The question I posed about the ability of the Robinson design to achieve certification if it were proposed to the FAA as a new design. The question stems from the fact that there are several non-compliances with the requirements of AC-27-1 dated 8-29-85 and CFR 14 Part 27 (Airworthiness Standards: Normal Category Rotorcraft Revised 1-1-94.
Add to this, the FAA has stated that flying out of trim and sideslipping would result in possible mast bumping and rotor incursion due to the flapping extremes on the rotor system when exposed to these maneuvers. To gain certification a helicopter must be flown in a 90-degree sideslip at .68 VNE both left and right and, it must be flown 10-degrees out of trim at the same speed yet the FAA has placed a “restriction” on these maneuvers. If Frank Robinson presented his helicopter to the FAA for certification and he told them of the non-compliance’s with the regs. And that his helicopter could not be sideslipped or flown out of trim they would refuse certification (IMHO)
Add the rigging procedures, which are totally different from any other helicopter. The procedures place the mechanic in a bad position in trying to rectify the written procedures with what he knows to be correct.
I would strongly suggest that those members of this forum that fly Robinson products read the rigging procedures and if they don’t understand them ask a mechanic to explain what they mean and the discrepancies in the procedures.
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Lu,
I don't know where you get your sideslip certification 'facts" from but you are way off base.
No helicopter I know of except Comanche is capable of what you think every helicopter must do ("To gain certification a helicopter must be flown in a 90-degree sideslip at .68 VNE both left and right and, it must be flown 10-degrees out of trim at the same speed yet the FAA has placed a “restriction” on these maneuvers.")
Also, the idea of "grandfathering" is not a new one to ppruners, please don't single out the Robbie as the lone participant.
Regarding sideslip sensitivity, the entire semi-rigid rotor fleet, including all Hueys is susceptable to the excessive flapping/mast bumping problem that you describe.
Regarding rigging, you are a broken record, and you are so far off base on the delta three rigging procedures it isn't worth wasting electrons posting a rebuttal. The Comanche rigging had VARIABLE swashplate tilt phase angle (gamma) as a function of SPEED, Lu. That is how little you know about helicopter aerodynamics. If you stuck to what you know, your contributions would be so very strong. However, when you yet again climb on your soapbox, it is almost embarassing.
The problem with that Robbie that was the subject of this thread until you hijacked it - the trailing edge crack - is possibly due to the excessive stiffness in the rotor head as described in the initial reports. This stress rise might be a strong contributor to blade forces and thus a stressor that can help cause a crack. The semi-useless speculation cannot help the stuation, especially when it goes so very far afield. The quality of the investigations in Britain is very high, let's see what the facts are, shall we?
I don't know where you get your sideslip certification 'facts" from but you are way off base.
No helicopter I know of except Comanche is capable of what you think every helicopter must do ("To gain certification a helicopter must be flown in a 90-degree sideslip at .68 VNE both left and right and, it must be flown 10-degrees out of trim at the same speed yet the FAA has placed a “restriction” on these maneuvers.")
Also, the idea of "grandfathering" is not a new one to ppruners, please don't single out the Robbie as the lone participant.
Regarding sideslip sensitivity, the entire semi-rigid rotor fleet, including all Hueys is susceptable to the excessive flapping/mast bumping problem that you describe.
Regarding rigging, you are a broken record, and you are so far off base on the delta three rigging procedures it isn't worth wasting electrons posting a rebuttal. The Comanche rigging had VARIABLE swashplate tilt phase angle (gamma) as a function of SPEED, Lu. That is how little you know about helicopter aerodynamics. If you stuck to what you know, your contributions would be so very strong. However, when you yet again climb on your soapbox, it is almost embarassing.
The problem with that Robbie that was the subject of this thread until you hijacked it - the trailing edge crack - is possibly due to the excessive stiffness in the rotor head as described in the initial reports. This stress rise might be a strong contributor to blade forces and thus a stressor that can help cause a crack. The semi-useless speculation cannot help the stuation, especially when it goes so very far afield. The quality of the investigations in Britain is very high, let's see what the facts are, shall we?
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Hi
Out of the struggle between a machine customers desire and a machine engineers dont like..
I am interested in having a real feedback about the R22 blade design and possible problems.
I am not eng so, excuse my little ignorance, but, roughly, i would try some remarks, to rise come counter arguments from real teatched people here :
i find this blade dangerously designed..
the blade grip is made of metal while the rest is composites, maybe i am wrong but isnt there a real stress riser and a break in finite element ?
Why wasnt this blade full composites with a metal struts inside linked to a all-metal blade grip?
I see there is a brutal section change in the blade grip, typical stresse riser, why not a thicker blade root for progressive bending and effort spreading ?
About the blade pockets craks : is it delamination ?
And a basical question, what are these problems due to ?
a quick design-for-market process ? a lack of innovation or an exess of it ?
Thank you for every valuable reply.
Victor
Out of the struggle between a machine customers desire and a machine engineers dont like..
I am interested in having a real feedback about the R22 blade design and possible problems.
I am not eng so, excuse my little ignorance, but, roughly, i would try some remarks, to rise come counter arguments from real teatched people here :
i find this blade dangerously designed..
the blade grip is made of metal while the rest is composites, maybe i am wrong but isnt there a real stress riser and a break in finite element ?
Why wasnt this blade full composites with a metal struts inside linked to a all-metal blade grip?
I see there is a brutal section change in the blade grip, typical stresse riser, why not a thicker blade root for progressive bending and effort spreading ?
About the blade pockets craks : is it delamination ?
And a basical question, what are these problems due to ?
a quick design-for-market process ? a lack of innovation or an exess of it ?
Thank you for every valuable reply.
Victor
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Once again into the breech.
To: NickLappos and anyone else that will listen.
Regarding what a helicopter must demonstrate I provide the following.
AC-27-1 paragraph 27.177.b.2 recognizes that some helicopters experience excessive flapping of the main and tail rotors when the helicopter is in a sideslip. To establish this side slip/flapping limits the respective rotors should be instrumented. CFR-14-27.177 requires testing of the controllability at side slip (out of trim) of plus 10-degrees, left and right (at 0.6 VNE) and CFR-14-27.351 requires full deflection of the tail rotor pedals while airborne from 0 to 0.6 VNE to attain a ninety degree side slip (left and right).
I goofed by saying 0.68 VNE
Let's assume that Robinson demonstrated these requirements and the FAA approved the demonstration. When the Robinson R-22 started falling out of the sky minus their rotor the NTSB became involved and recommended the de-certification of the helicopter. The FAA refused for whatever reason. I personally believe that they had to save face for granting the certification.
The FAA contracted with Georgia Tech the same school that NickLappos attended requesting that they determined what was the root cause of these accidents. They determined that when the helicopter was flown out of trim or placed in a sideslip there was a resultant high degree of flapping of the main rotor resulting in mast bumping and/or rotor incursion. As a result the FAA issued a priority letter to Robinson outlining the causes of the accidents and several procedures that had to be eliminated to prevent the mast bumping and rotor incursions. Two of the maneuvers to be avoided were side slipping and flying out of trim. These were the same maneuvers that had to be demonstrated for certification. From this I drew the conclusion that if the R-22 were presented at this time for certification with these same restrictions the FAA would not grant certification. Maybe I’m wrong but that is my opinion. You are entitled to yours.
Regarding my addressing the rigging procedures it had absolutely nothing to do with an 18-degree offset or anything related to it. The rigging procedures are wrong and are totally different from any other helicopter. Before accusing me of being wrong I suggest you familiarize yourself with the rigging procedures.
Another point to consider relative to the blade cracks when the blades flap about the cone hinge they will lead and lag. Since there is no vertical hinge the lead lag loads will be reacted by the cone hinge. These loads must pass through the blades so the blades are subjected to inplane bending at a very high frequency resulting in fatigue (IMHO).
Still another point to consider that the R-22 unlike other helicopters,which are certified by the helicopter certification branch in Texas was in fact certified by The Los Angeles Aircraft Certification Office of the Transport Airplane Directorate. Is there a possibility that this office had no knowledge base relative to helicopters and did not fully understand the certification requirements? Just a thought.
I did not hijack the thread. I responded to what VFRpilotpb had stated and it went from there.
Regarding what a helicopter must demonstrate I provide the following.
AC-27-1 paragraph 27.177.b.2 recognizes that some helicopters experience excessive flapping of the main and tail rotors when the helicopter is in a sideslip. To establish this side slip/flapping limits the respective rotors should be instrumented. CFR-14-27.177 requires testing of the controllability at side slip (out of trim) of plus 10-degrees, left and right (at 0.6 VNE) and CFR-14-27.351 requires full deflection of the tail rotor pedals while airborne from 0 to 0.6 VNE to attain a ninety degree side slip (left and right).
I goofed by saying 0.68 VNE
Let's assume that Robinson demonstrated these requirements and the FAA approved the demonstration. When the Robinson R-22 started falling out of the sky minus their rotor the NTSB became involved and recommended the de-certification of the helicopter. The FAA refused for whatever reason. I personally believe that they had to save face for granting the certification.
The FAA contracted with Georgia Tech the same school that NickLappos attended requesting that they determined what was the root cause of these accidents. They determined that when the helicopter was flown out of trim or placed in a sideslip there was a resultant high degree of flapping of the main rotor resulting in mast bumping and/or rotor incursion. As a result the FAA issued a priority letter to Robinson outlining the causes of the accidents and several procedures that had to be eliminated to prevent the mast bumping and rotor incursions. Two of the maneuvers to be avoided were side slipping and flying out of trim. These were the same maneuvers that had to be demonstrated for certification. From this I drew the conclusion that if the R-22 were presented at this time for certification with these same restrictions the FAA would not grant certification. Maybe I’m wrong but that is my opinion. You are entitled to yours.
Regarding my addressing the rigging procedures it had absolutely nothing to do with an 18-degree offset or anything related to it. The rigging procedures are wrong and are totally different from any other helicopter. Before accusing me of being wrong I suggest you familiarize yourself with the rigging procedures.
Another point to consider relative to the blade cracks when the blades flap about the cone hinge they will lead and lag. Since there is no vertical hinge the lead lag loads will be reacted by the cone hinge. These loads must pass through the blades so the blades are subjected to inplane bending at a very high frequency resulting in fatigue (IMHO).
Still another point to consider that the R-22 unlike other helicopters,which are certified by the helicopter certification branch in Texas was in fact certified by The Los Angeles Aircraft Certification Office of the Transport Airplane Directorate. Is there a possibility that this office had no knowledge base relative to helicopters and did not fully understand the certification requirements? Just a thought.
I did not hijack the thread. I responded to what VFRpilotpb had stated and it went from there.
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Don't you wish that people could spell words like "manoeuvres" ? I mean, we can accept "familiarize" because our US friends have a thing about z in place of s. But "maneuvers"........
And when is someone going to tell Microsoft that Favorites is actually Favourites ?
Oops. Sorry. Hijacked thread alert.
And when is someone going to tell Microsoft that Favorites is actually Favourites ?
Oops. Sorry. Hijacked thread alert.
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Lu,
Someday, when you know FAR's you'll understand. The 27.351 is a STRENGTH requirement, as I have told you at least twice before. It is not a demonstration to 90 degrees of sideslip, NOBODY does that maneuver, it is for analysis of the structure.
There are similar holes in the rest of your anti-Robinson polemic.
Give us a rest, please.
Someday, when you know FAR's you'll understand. The 27.351 is a STRENGTH requirement, as I have told you at least twice before. It is not a demonstration to 90 degrees of sideslip, NOBODY does that maneuver, it is for analysis of the structure.
There are similar holes in the rest of your anti-Robinson polemic.
Give us a rest, please.
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Differing points of view.
To: NickLappos
You are correct 14-27.351 deals with the structural loads reacted when placing the helicopter in a 90-degree sideslip right and left at speeds from 0 to 0.6 VNE. The point I was trying to make is that this maneuver when demonstrated under 14-27.351 would cause extreme flapping of the main rotor. This conclusion is based on the Georgia Tech evaluation of the problem and how the FAA reacted to this report. They placed restrictions on out of trim flight and sideslipping stating that this would result in extreme flapping of the rotor system resulting in either mast bumping or rotor incursion or both.
AC-27-1 paragraph 27.177.b.2 recognizes that some helicopters experience excessive flapping of the main and tail rotors when the helicopter is in a sideslip. To establish this side slip/flapping limits the respective rotors should be instrumented. CFR-14-27.177 requires testing of the controllability at side slip (out of trim) of plus 10-degrees, left and right (at 0.6 VNE) and CFR-14-27.351 requires full deflection of the tail rotor pedals while airborne from 0 to 0.6 VNE to attain a ninety degree side slip (left and right).
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Yes Lu, you were wrong when you wrote : "CFR-14-27.351 requires full deflection of the tail rotor pedals while airborne from 0 to 0.6 VNE " That was WRONG Lu.
I know you will never admit it, I know you will wait about 6 months and post your incorrect misunderstanding yet again as if it was right, I know you will answer this with yet another interminably long re-hash and smearing of what was said so you don't actually have to admit you were wrong. I only wish that you were aware of these things when you start speculatively smearing someone's product or work or efforts.
I know you will never admit it, I know you will wait about 6 months and post your incorrect misunderstanding yet again as if it was right, I know you will answer this with yet another interminably long re-hash and smearing of what was said so you don't actually have to admit you were wrong. I only wish that you were aware of these things when you start speculatively smearing someone's product or work or efforts.
Last edited by NickLappos; 28th Nov 2004 at 01:12.
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I'm still in the breech.
To: NickLappos
CFR-14-351 paragraph (2b) states: To produce the load required in paragraph (a) of this section, in unaccelerated flight with zero yaw, at forward speeds from zero up to 0.6 VNE followed by paragraph (1) Displace the cockpit directional control suddenly to the maximum deflection limited by the control stops or, by pilot force specified in 27-395 (Note: the R-22 control system is very simple and offers no resistance to pilot input other than that generated by the tail rotor and therefore CFR-14-395 does not apply.
This is followed by paragraph (2) which states, Attain a resulting sideslip angle of 90-degrees, whichever is less. The controls are suddenly returned to neutral and the test is repeated in the opposite direction.
Yes Lu, you were wrong when you wrote : "CFR-14-27.351 requires full deflection of the tail rotor pedals while airborne from 0 to 0.6 VNE " That was WRONG Lu.
CFR-14-351 paragraph (2b) states: To produce the load required in paragraph (a) of this section, in unaccelerated flight with zero yaw, at forward speeds from zero up to 0.6 VNE followed by paragraph (1) Displace the cockpit directional control suddenly to the maximum deflection limited by the control stops or, by pilot force specified in 27-395 (Note: the R-22 control system is very simple and offers no resistance to pilot input other than that generated by the tail rotor and therefore CFR-14-395 does not apply.
This is followed by paragraph (2) which states, Attain a resulting sideslip angle of 90-degrees, whichever is less. The controls are suddenly returned to neutral and the test is repeated in the opposite direction.
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OK Lu, here AGAIN is what you said that was WRONG: "CFR-14-27.351 requires full deflection of the tail rotor pedals while airborne" The regulation that you accused Robinson of failing to meet is an analytical one, not a flight demonstration. You were wrong to say it was, and wrong to accuse Robinson of failing to meet it. WRONG, Lu. WRONG.
As usual, you are incapable of knowing what you say, your posts are worthless as a result. WORTHLESS. It is a pity.
As usual, you are incapable of knowing what you say, your posts are worthless as a result. WORTHLESS. It is a pity.
Better red than ...
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About 20 posts ago somebody emntioned that by implication the R44 had the same fatal flaw in the rotor head as the R22.
Has there (ever) been in the UK any cause of accident associated with this type of fault ?
The R44 has almost caught the R22 in terms of machines in service in the UK, although not flying hours of course as the 22 has a few years head start.
Has there (ever) been in the UK any cause of accident associated with this type of fault ?
The R44 has almost caught the R22 in terms of machines in service in the UK, although not flying hours of course as the 22 has a few years head start.
Nick / Lu
Not that I fly Robinson products, but answer a simple question without all the gobbledygock. Does full pedal deflection in an R22 create xs flapping of the blades, so much so that mast bumping / rotor incursion occurs ?
Lu presumably you will say yes with Georgia Tech's view
Nick presumably you will say no. But Nick do you go against Geogia Tech and if so why ?
While talking of peal deflection the MD600 was only certified in UK with a 135 kt VNE due to out of balance problems above that speed.
I am now retreating to my old air raid shelter
Not that I fly Robinson products, but answer a simple question without all the gobbledygock. Does full pedal deflection in an R22 create xs flapping of the blades, so much so that mast bumping / rotor incursion occurs ?
Lu presumably you will say yes with Georgia Tech's view
Nick presumably you will say no. But Nick do you go against Geogia Tech and if so why ?
While talking of peal deflection the MD600 was only certified in UK with a 135 kt VNE due to out of balance problems above that speed.
I am now retreating to my old air raid shelter
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Hughes500,
I haven't read the Ga Tech report (I went there once upon a time).
I am responding to Lu's typical misguided polemic against Robinson, where he misquotes requirements, misunderstands basic design principles and hangs the guilty, as usual.
No helicopter that I know except Comanche can easily withstand this enormous pedal input and retain control or rotor structural integrity, and no helicopter is required to perform that maneuver. Teetering rotors will flap wildly, and will perhaps mast bump, with disasterous results. This includes all Hueys, robbies and the like. Lu's laser focus on Robinson is just part of his crusade.
I haven't read the Ga Tech report (I went there once upon a time).
I am responding to Lu's typical misguided polemic against Robinson, where he misquotes requirements, misunderstands basic design principles and hangs the guilty, as usual.
No helicopter that I know except Comanche can easily withstand this enormous pedal input and retain control or rotor structural integrity, and no helicopter is required to perform that maneuver. Teetering rotors will flap wildly, and will perhaps mast bump, with disasterous results. This includes all Hueys, robbies and the like. Lu's laser focus on Robinson is just part of his crusade.
Last edited by NickLappos; 28th Nov 2004 at 16:31.
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To Nick L and Lu Z
I would love to get you two in a bar, maybe with Frank R and my old friend Pat Cox, throw in a question, buy the drinks and sit back and just listen - fascinating.
I would love to get you two in a bar, maybe with Frank R and my old friend Pat Cox, throw in a question, buy the drinks and sit back and just listen - fascinating.