R22 Technical Question
 

Can anyone tell me what function the bushing through the shackle on the front undercarriage/fuselage fixings of the R22 undercarriage perform and what effect would it have if they were not installed?

... people would take every opportunity to tell you that the helicopter is unsafe? ....:eek:

Probably throw the C 0f G out of limits... :-D

"Can I have a shackle bushing for an R22 please?"

"Sounds like a fair trade, here you go"

Earwiggo..................

Seriously though,

The bushings are meant to be there, if they are not it IS a problem.

Which bushing specifically are you worried about?

http://www.robinsonheli.com/service_.../r22_sb40.pdf.

Unnecessary vibro and wear would surely be a concern?

I noticed a resonance during high hovers, could this be the cause?

If the shackle / bushing isn't intimately involved in producing power or transmitting it to the blades I'd suggest it's extremely unlikely be a source of vibration?

Helidogger, why not have all the parts fitted that make up the certified airframe? I am not an expert on maintenance issues, but in all generality I would assume that the a/c with any part missing cannot be deemed airworthy.

I once had a kink in the skid, and the a/c was grounded until a new skid was fitted. Reason given was the the each skid (including their uncompromised structural integrity that may be affected by the kink) forms part of the crashworthy undercarriage, where each part is presumed to absorb its share of the impact energy in a hard landing.

Resonance in high hover: Have you already tried blade tracking?

I asked the question because during a 12 year inspection it was discovered that a bush was missing from the starboard front mount. Now to comply with airworthiness requirements I have had one fitted. I have not flown it yet and had hoped someone knowledgeable may have experience of such a situation.

The bush could well perform a damping function between the fuselage and the undercarriage - perhaps to prevent the natural rotor harmonics triggering resonance in the skids - especially on the ground.

If that were the case then it may well be the skids vibrating in the air due to the rotors.