R-22 ROTOR SEPARATION? Florida Photo
YIPEEE
TC and i agree on something 
I was tasked to take up a student way back in 1980 ( approx ) in one of these new fangled Robbos . I was only about 21 and had a couple of hundred hrs . To cut a long story short ....the student and i got back on the ground within 20 mins , got out and went and had a beer and a fag ( cigarette in US .....) . It was the most afraid i have ever been in a helicopter , incl the time a blade came through the cockpit !!!! I wrote a report to say that for an experienced pilot it may be fine but for someone of my ability and hrs it was a deathtrap
and it was totally unsuitable for low hr pilots and training .
That was my view then and i havent changed it in over 30 yrs .
I would train on a 300 or if you have to a 44 but NOT a 22.
TC and i agree on something I was tasked to take up a student way back in 1980 ( approx ) in one of these new fangled Robbos . I was only about 21 and had a couple of hundred hrs . To cut a long story short ....the student and i got back on the ground within 20 mins , got out and went and had a beer and a fag ( cigarette in US .....) . It was the most afraid i have ever been in a helicopter , incl the time a blade came through the cockpit !!!! I wrote a report to say that for an experienced pilot it may be fine but for someone of my ability and hrs it was a deathtrap
and it was totally unsuitable for low hr pilots and training .
That was my view then and i havent changed it in over 30 yrs .
I would train on a 300 or if you have to a 44 but NOT a 22.
Last edited by nigelh; 19th Feb 2013 at 13:19.
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Stretch?
Pardon my ignorance, but as an A&P with 18 years working on Sikorsky and some Bell stuff I've never heard of "stretching" a bolt. How exactly does that work?
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Instead of using a torque wrench you measure the bolt before you tighten the nut and then measure the length of it afterwards until you reach the required stretch figure. There is a jig that fits over the area that allows you to do this.
You're joking right?
I rebuild cars and come across steel bolts that have stretched. Every time a wrought iron or steel panel or bolt bends it stretches. I can easily imagine a MRH bolt stretching after 1000's of hours of centripetal force.
I rebuild cars and come across steel bolts that have stretched. Every time a wrought iron or steel panel or bolt bends it stretches. I can easily imagine a MRH bolt stretching after 1000's of hours of centripetal force.
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TC
I wasn't saying I don't get the idea of a bolt having some give, but I've sure as hell never seen it as a procedure.
Having spent most of my life in Sikorsky Hawks and 92's I'm not used to seeing sraight steel hdwr anyway. Most all of our stuff is Cad or Titanium. Think I'll stick with the 10,000 lbs+ class helicopters.
I wasn't saying I don't get the idea of a bolt having some give, but I've sure as hell never seen it as a procedure.
Having spent most of my life in Sikorsky Hawks and 92's I'm not used to seeing sraight steel hdwr anyway. Most all of our stuff is Cad or Titanium. Think I'll stick with the 10,000 lbs+ class helicopters.
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Would love to see a listing of the causes of all 39. Lousy maintenance?
my brother used to be in the fastening of bolts, big bolts using hrydanuts. I'll see if I can dig a couple of old photos one day soon. Installed many in most of the hot ends on nuclear powerhouses right round the world. One amusing story about how when trying to describe to his kids why he couldn't be called on cell phone one day, "these joints are designed so no radio waves get out, so nothing sure as hell can get in."
Those bolts sure seem to be this issue. Yesterday peddling around chasing bulls, big storm blew up lot of gusts, just absolutely nothing to give one the feeling that there was any shock loading to be had out of it. Seems to me there has got to be a shock loading on one side that must happen to cause the knee to break in the middle and understandable that each of the two joints being the weakest links or section would break simultaneously.
Thanks TC, yes I only read some of the late gentleman Zu's posts, but in reality I think if VF's friends are so damn clever they should all head over to FAA land and take over the certification processes and examinations processes of A&P people.
Despite all criticisms these gadgets have been approved by sound and well tested basic engineering and flight testing principles.
VF does an excellent job where he is all credit to him, but he can step away from common slander I think quite easy - all a bit different from personal preferences which are easy to respect. Slander earns the biffo response and I make no apologies in that respect
If we were all to get grounded tomorrow it should not be surprising, after all that sort of thing has happened before despite intense engineering effort, have a look at the B787 for example, the M/R grips on the B47's another.
cheers tet..
Avoid imitations
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bhawkh60 wrote:
Pardon my ignorance, but as an A&P with 18 years working on Sikorsky and some Bell stuff I've never heard of "stretching" a bolt. How exactly does that work?
... and, ...
I wasn't saying I don't get the idea of a bolt having some give, but I've sure as hell never seen it as a procedure.
Having spent most of my life in Sikorsky Hawks and 92's I'm not used to seeing sraight steel hdwr anyway. Most all of our stuff is Cad or Titanium. Think I'll stick with the 10,000 lbs+ class helicopters.
-------------------------------------
Yikes, I sure hope you are not licenced to actually sign off on anything
Pardon my ignorance, but as an A&P with 18 years working on Sikorsky and some Bell stuff I've never heard of "stretching" a bolt. How exactly does that work?
... and, ...
I wasn't saying I don't get the idea of a bolt having some give, but I've sure as hell never seen it as a procedure.
Having spent most of my life in Sikorsky Hawks and 92's I'm not used to seeing sraight steel hdwr anyway. Most all of our stuff is Cad or Titanium. Think I'll stick with the 10,000 lbs+ class helicopters.-------------------------------------
Yikes, I sure hope you are not licenced to actually sign off on anything
Last edited by oleary; 20th Feb 2013 at 05:41.
I think obsessing about the bolts is a red herring - even if they were made of titanium they would break because the design of the rotor head allows such high stresses to be placed on them.
If you haven't already read the latest UK AAIB report on the R22 fatal referred to earlier, it highlights that the extreme flapping that can be achieved by the R22 head creates an off-angle pull on the pitch change arm which can either tear the top end of the arm from the head or stress the bolt so much that it fails.
The 'clever' (and cheap) design of a teetering hinge flanked by two flapping or coning hinges allows too much flapping resulting in mast-bumping and mechanical stress on the head.
If you haven't already read the latest UK AAIB report on the R22 fatal referred to earlier, it highlights that the extreme flapping that can be achieved by the R22 head creates an off-angle pull on the pitch change arm which can either tear the top end of the arm from the head or stress the bolt so much that it fails.
The 'clever' (and cheap) design of a teetering hinge flanked by two flapping or coning hinges allows too much flapping resulting in mast-bumping and mechanical stress on the head.
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Stretching Bolts
I was helping a LAME rebuild a Schweizer rotorhead passing tools etc. (incidentally a great way to learn how they work) and I can vouch for the fact that the procedure called for the blade bolts to be measured, and then torqued until they had stretched "X" thousand of an inch, where X is a number I cannot recall exactly but think was 9 thou, or about 0.23 mm.
For the benefit of SHY: the picture is not of the same bolt. The 'NEW' bolt is a new bolt. The 'OLD' bolt is another bolt but older. Because the bolts are not mandated to be identical or same batch, the bolt heads can be different, so too the collar. As long as the thread is the same in terms of diameter and length, that is all that matters. Sometimes, Shy, the bolts are different colours too
But this example (because it is just an example) shows them to be the same colour for simplicity (and because I didn't have different coloured bolts).
However, you missed a trick: I could have raised the old bolt a little higher and that would have shown the phenomena to be even more prevalent. But that would be cheating and people like you would have commented.
Would you like me to show you the other end of the bolts?
But this example (because it is just an example) shows them to be the same colour for simplicity (and because I didn't have different coloured bolts).However, you missed a trick: I could have raised the old bolt a little higher and that would have shown the phenomena to be even more prevalent. But that would be cheating and people like you would have commented.
Would you like me to show you the other end of the bolts?
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Nigelh. In 1980 the R22 was Certified in the Private Cat. Therefore your student must of been an owner. There was only one company training at that time and the training was for the owner on the owners helicopter. I might be mistaken but I knew all the customers (not many at that time) and do not remember such a situation.
Dont you worry ...were all bullys here
Dick ....I may be a year out and it could have been 81. It came to Simpson Helicopters in Houston to be evaluated as a trainer . Very low inertia blades ....0.1 sec to get lever down ....scary
Dick ....I may be a year out and it could have been 81. It came to Simpson Helicopters in Houston to be evaluated as a trainer . Very low inertia blades ....0.1 sec to get lever down ....scary
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oleary
You've got to be kidding me. You can read Sikorsky tech pubs or FAA hardware study guides all day long and will never find reference one to "stretching" a bolt. It's all TQ values.
As far as "Yikes, I sure hope you are not licenced to actually sign off on anything ":
What part of A&P confused you?
You've got to be kidding me. You can read Sikorsky tech pubs or FAA hardware study guides all day long and will never find reference one to "stretching" a bolt. It's all TQ values.
As far as "Yikes, I sure hope you are not licenced to actually sign off on anything
":What part of A&P confused you?