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REPAIR OF MAGNESIUM GEAR BOX CASING
2006
DEAR SIR,
WE ARE FACING A PROBLEM IN THE REPAIR IF GEAR BOX CASNG.THE PROBLEM IS THAT AFTER THE BEARINGS AARE REMOVED FROM THE CASING THE BORE SIZE ETS ENLARGED BY 15 TO20 MICRONS.
WE CANNOT DISCARD THE CASING SINCE IT IS VERY COSTLY.
HELICOPTER DIVISION - Bangalore, INDIA
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You can not just make any repair. You must follow the overhaul instructions of the OEM for that repair. Typical would be to mill it appropriately oversize, plate it and then grind to final size. Thermal spray has replaced some chrome and nickel applications. James Watts- Navarre, Florida One approach would be to machine the bearing housing oversize, then install a bush to bring it back to the required ID to suit the bearing OD.  Bill Reynolds [deceased] consultant metallurgist - Ballarat, Victoria, Australia We sadly relate the news that Bill passed away on Jan. 29, 2010. It may be possible to build up the bore area with a hard anodic coating such as Magoxid-Coat(r). Chris Jurey, Past-President IHAALuke Engineering & Mfg. Co. Inc.  Wadsworth, Ohio  One common way of dealing with oversize bores during repair and overhaul is to machine the bore first to regain concentricity and then fit a liner of the appropriate size to bring the bore back to operational tolerance. The liner may be interference fitted in most cases. Aerospace - Yeovil, Somerset, UK |
2006
Sir,
this is problem regarding magnesium alloy (rz5) housing bores which are being oversized when they are coming for overhaul after 500 hours of servicing. helicopters using magnesium alloy housings for its gear boxes is facing this problem. the oversizing is around 65microns. so please suggest how to develop material/ protective coating to avoid oversize/ any other procedures which makes use of rejected housings.
thanking you sir,
aeronautics - India
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