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Main Rotor Support and Bumpers

The military main rotor was modified with a plate bolted to the bottom of the main rotor yoke and a support bolted to the mast just above the stabilizer bar dampers, with bumpers. The plate end flanges would contact the bumpers. In this configuration the main rotor mast pole is limited to 1,500 hour life even if the bumper system was removed.

If the mast pole is installed new without ever having the bumper system installed, with 1,500 hour overhauls it’s life is 10,000 hours.

Pictured is a main rotor with the support and bumpers removed the plate still in place the steel plate will contact the mast and can DAMAGE the mast.

I am guessing the plate was left in place as it has the worm screw’s to position the inboard fittings and strap for flight with hydraulics off. The whole system should be removed and be replaced with 204-012-105-1 stop assembly ( 2ea.), AN6H6a bolts ( 4 ea.) and you can reuse the washers 140-007-25S20A4 ( 4ea. ) from the plate retaining bolts and 204-012-108-1 ( ea. ) rubber stops.'

These stops are the original and are what is used on commercial aircraft and have the worm screws for adjusting the fittings & straps for hydraulics off. Install in accordance with the Manual.

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