R22 Accident Analysis 1979-1994
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What ho Squiffy!
I guess the R22 and the Bell 47 are a bit chalk and cheese as you say, but I think that the R22 had more relevance in teaching people to fly a modern helicopter, as it has a low inertia rotor in common with many of the helicopters now flying in Europe. Despite the teetering rotor (which is also the cause of some of its handling problems) the offset hinges also give it quite good control power (waits to be shot down by a real expert here!!)which is also similar to many of the modern helicopters students would hope to go on to fly.
It has to be said that the reason the school where I was working at the time changed was purely for reasons of cost, (the other types being considered being Schwiezer 300 and Enstrom F28) but the R22 appeared to offer considerable cost savings over anything else. Most of our students went straight from the R22 to the AS332L or S76.
I guess the R22 and the Bell 47 are a bit chalk and cheese as you say, but I think that the R22 had more relevance in teaching people to fly a modern helicopter, as it has a low inertia rotor in common with many of the helicopters now flying in Europe. Despite the teetering rotor (which is also the cause of some of its handling problems) the offset hinges also give it quite good control power (waits to be shot down by a real expert here!!)which is also similar to many of the modern helicopters students would hope to go on to fly.
It has to be said that the reason the school where I was working at the time changed was purely for reasons of cost, (the other types being considered being Schwiezer 300 and Enstrom F28) but the R22 appeared to offer considerable cost savings over anything else. Most of our students went straight from the R22 to the AS332L or S76.
Iconoclast
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You are wrong because I am right. If you disagree with that I am taking my toys home
To: t'aint natural
There are no design defects in the Robinson rotor system. However there are effects relating to the design that cause the problems.
The head design is unique in that the downward force of the weight of the rotorblades on the down stops keeps the rotor in the neutral position when static on the ground. This function is similar to the stops on Bell heads. However, this feature also prevents the teetering of the rotor by the pilot or engineer while the helicopter is at rest as to do so could cause damage to the rotor head. These same down stops can be contacted during flight if the blades flap excessively resulting in rotor incursion or mast bumping. However the Bell teeter stops are not contacted during flight. Why do the blades flap excessively? Because they are free to flap on the cone hinges. Why don’t’ Bell blades flap excessively because the are not free to flap (on cone hinges) and it is for this reason that Bell helicopters are not restricted from flying out of trim or fly in a side slip. You made the comment about "Taking a lend” (I assume this means following) of the operating instructions and you will not have any problems. The operating instructions you are alluding to are in place because of the “EFFECT” of the rotor design as outlined above.
I don’t remember if it was you that made the comment of me being a one-act pony but I would like to correct that statement. I am an equal opportunity Iconoclast in that I have criticized Bell products, Agusta products, Sikorsky products, Hughes products and Bell-Boeing products. Also if you have read my posts on the Tech Log Forum I openly criticized Airbus products. I don’t shoot from the hip as I make my criticisms as a result of having worked on the products in question in an engineering capacity. Any comments I made about the Robinson design stems from my past experience on the other designs listed above. This also holds true for my comments about gyroscopic precession and centrifugal force as well as rotor dynamics.
Don’t take this personally as it relates to many other members of this forum.
Rotorheads is a place where ideas can be exchanged between consenting adults. At times individuals can agree with the points being made and they can also disagree with the posters point of view and they can register their point of view in response.
However, first and foremost because the respondent disagrees with the ideas being presented does not mean that the original post and the poster are wrong simply because the respondent disagrees.
Cases in point:
1) Gyroscopic precession VS. Aerodynamic precession
2) Flapping to equality VS. Blowback or, Flapback
3) Centrifugal force VS. Centripetal force*
* Read the patent application for the Robinson rotor head design.
There are no design defects in the Robinson rotor system. However there are effects relating to the design that cause the problems.
The head design is unique in that the downward force of the weight of the rotorblades on the down stops keeps the rotor in the neutral position when static on the ground. This function is similar to the stops on Bell heads. However, this feature also prevents the teetering of the rotor by the pilot or engineer while the helicopter is at rest as to do so could cause damage to the rotor head. These same down stops can be contacted during flight if the blades flap excessively resulting in rotor incursion or mast bumping. However the Bell teeter stops are not contacted during flight. Why do the blades flap excessively? Because they are free to flap on the cone hinges. Why don’t’ Bell blades flap excessively because the are not free to flap (on cone hinges) and it is for this reason that Bell helicopters are not restricted from flying out of trim or fly in a side slip. You made the comment about "Taking a lend” (I assume this means following) of the operating instructions and you will not have any problems. The operating instructions you are alluding to are in place because of the “EFFECT” of the rotor design as outlined above.
I don’t remember if it was you that made the comment of me being a one-act pony but I would like to correct that statement. I am an equal opportunity Iconoclast in that I have criticized Bell products, Agusta products, Sikorsky products, Hughes products and Bell-Boeing products. Also if you have read my posts on the Tech Log Forum I openly criticized Airbus products. I don’t shoot from the hip as I make my criticisms as a result of having worked on the products in question in an engineering capacity. Any comments I made about the Robinson design stems from my past experience on the other designs listed above. This also holds true for my comments about gyroscopic precession and centrifugal force as well as rotor dynamics.
Don’t take this personally as it relates to many other members of this forum.
Rotorheads is a place where ideas can be exchanged between consenting adults. At times individuals can agree with the points being made and they can also disagree with the posters point of view and they can register their point of view in response.
However, first and foremost because the respondent disagrees with the ideas being presented does not mean that the original post and the poster are wrong simply because the respondent disagrees.
Cases in point:
1) Gyroscopic precession VS. Aerodynamic precession
2) Flapping to equality VS. Blowback or, Flapback
3) Centrifugal force VS. Centripetal force*
* Read the patent application for the Robinson rotor head design.
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Wear in cone/flap hinges
Lu, you had a concern about wear in the cone/flap hinges of the R-22 head. The following bit of information should be of interest, and may be of interest to others.
I was talking to the director of maintenance for a large authorized Robinson maintenance company and I asked him about wear in the rotor head. He said that they maintained sixty R-22's. Many are used as logging company pickup trucks, and spend much time hovering, where the rotor torque is constantly changing. These helicopter have their teetering bearings changed every 300-500 hours, where as the regularly used ones have this bearing changed every 1000-1200 hours.
He said that they had never replaced a cone/flap bearing and that they appear to be good for the life of the helicopter.
I was talking to the director of maintenance for a large authorized Robinson maintenance company and I asked him about wear in the rotor head. He said that they maintained sixty R-22's. Many are used as logging company pickup trucks, and spend much time hovering, where the rotor torque is constantly changing. These helicopter have their teetering bearings changed every 300-500 hours, where as the regularly used ones have this bearing changed every 1000-1200 hours.
He said that they had never replaced a cone/flap bearing and that they appear to be good for the life of the helicopter.
Thread Starter
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Why do I rise to this? Lu, you've said it all before. It was crap then, and it's crap now. Like I say, all you have to do is build a better helicopter than Frank Robinson did. You can nick all the stuff he got right, add your own design of the stuff he got wrong, and presto! The Z22. Then instead of wasting your time bellyaching about something you know nothing about, you'll have made a real contribution to the industry.
If you have time to waste, why not learn to fly? Or take some lessons in basic design? That'd help.
PS I didn't say you were a one-trick pony. I said you were a fixated monomaniac with a fetish.
If you have time to waste, why not learn to fly? Or take some lessons in basic design? That'd help.
PS I didn't say you were a one-trick pony. I said you were a fixated monomaniac with a fetish.
Iconoclast
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I'll show you mine if you show me yours.
To: t'aint natural
Quote: “Then instead of wasting your time bellyaching about something you know nothing about, you'll have made a real contribution to the industry.
If you have time to waste, why not learn to fly? Or take some lessons in basic design? That'd help”.
Regarding the first sentence above about knowing what I am talking about I alluded to my past experience, which is:
Eighteen factory technical schools on helicopters to include the P&W Twinpack and the Allison 250.
Fourteen month training program at Sikorsky.
Two military schools on aircraft, helicopters and engines.
Worked as a design analyst specializing in Reliability, Maintainability and Systems Safety on the following:
Agusta 129
Agusta-Westland EH 101
AH-64 Apache
AH-56 Cheyenne
Bell-Boeing V-22
Supervised the maintenance engineering department for Bell Helicopter International on the following:
AB 206
AB 205
Bell 214
Bell AH1-J
Agusta-Boeing CH-47
Agusta-Sikorsky SH3-D
I believe this gives me sufficient standing to be critical about anything related to helicopters that effect reliability, maintenance or safety.
Regarding my learning to fly. I did a lot of that in the service as a flight engineer or helicopter maintenance mechanic. There is a strong possibility that I was doing this before you were born.
It seems that you were attacking me but failing to respond to what I mentioned in my post above.
Quote: “Then instead of wasting your time bellyaching about something you know nothing about, you'll have made a real contribution to the industry.
If you have time to waste, why not learn to fly? Or take some lessons in basic design? That'd help”.
Regarding the first sentence above about knowing what I am talking about I alluded to my past experience, which is:
Eighteen factory technical schools on helicopters to include the P&W Twinpack and the Allison 250.
Fourteen month training program at Sikorsky.
Two military schools on aircraft, helicopters and engines.
Worked as a design analyst specializing in Reliability, Maintainability and Systems Safety on the following:
Agusta 129
Agusta-Westland EH 101
AH-64 Apache
AH-56 Cheyenne
Bell-Boeing V-22
Supervised the maintenance engineering department for Bell Helicopter International on the following:
AB 206
AB 205
Bell 214
Bell AH1-J
Agusta-Boeing CH-47
Agusta-Sikorsky SH3-D
I believe this gives me sufficient standing to be critical about anything related to helicopters that effect reliability, maintenance or safety.
Regarding my learning to fly. I did a lot of that in the service as a flight engineer or helicopter maintenance mechanic. There is a strong possibility that I was doing this before you were born.
It seems that you were attacking me but failing to respond to what I mentioned in my post above.
Last edited by Lu Zuckerman; 16th Jul 2002 at 19:38.
Taint - now you've gone and done it!! We'll all have to hide on another thread until he goes away again!
An R22 is an impressive machine in the right (experienced hands) unfortunately the majority of owners and hirers are low time pilots who may also fly infrequently (skill fade). These are the sort of pilots making up the accident stats and it's not really their fault. It is widely recognised that continuity of flying experience is very important and getting airborne for an hour every couple of months just isn't enough to keep you on top of the Robbo.
PS Lu you forgot the argument you lost about pitch change rods and their varying rate of movement around a control orbit...
Oh Bugg*r now I've done it too......
An R22 is an impressive machine in the right (experienced hands) unfortunately the majority of owners and hirers are low time pilots who may also fly infrequently (skill fade). These are the sort of pilots making up the accident stats and it's not really their fault. It is widely recognised that continuity of flying experience is very important and getting airborne for an hour every couple of months just isn't enough to keep you on top of the Robbo.
PS Lu you forgot the argument you lost about pitch change rods and their varying rate of movement around a control orbit...
Oh Bugg*r now I've done it too......
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Having worked for a company that had flown a couple hundred thousand commercial R22 and R44 hours without a single loss of control accident like that which worries Lu and the FAA so much, I'd like to make an observation.
The key to safe flying in these machines is currency and respect.
We have also noted that new-hire pilots who are very low-time and were trained on machines like the Bell47 have a difficult time adjusting to the low inertia rotor. They retain habits that are very inapplicable to the new type and tend to be slow to pick up the new skills.
I can't imagine hopping into a machine for a couple hours every couple months and feeling safe, let alone owning a helicopter and renting it out to someone like this! Its a serious business.
The key to safe flying in these machines is currency and respect.
We have also noted that new-hire pilots who are very low-time and were trained on machines like the Bell47 have a difficult time adjusting to the low inertia rotor. They retain habits that are very inapplicable to the new type and tend to be slow to pick up the new skills.
I can't imagine hopping into a machine for a couple hours every couple months and feeling safe, let alone owning a helicopter and renting it out to someone like this! Its a serious business.
