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TRANSCRIPT
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An AS 9100C and
ISO 14001-2004 Company
xnix Bx]C ]bHINDUSTAN AERONAUTICS LIMITED
J<
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As a way forward Russian side has proposed 20 recommendations (11 for
Manufacturing and 9 for Exploitation) after Joint Investigation was carried out
along with Indian side. Recommendation is given for modification of Inter Rotor
bearing (Part No: 5-272822P2Y) with improved cooling of the Bearing byintroduction of additional Lubrication oil supply holes.
Indian side is of the opinion that this recommendation is a short term solution
to the Bearing failure problem. Other critical design aspects such as Material
characteristics of the Bearing races and Rollers, Micro-structural changes leading to
plastic deformation during operation, Material erosion and Load characteristics need
to be introspected and validated.
Preliminary findings/Analysis of the Cat-A Bearings vis a vis failed Engine
Bearing reveal the following:1. Inter-shaft bearing (55-2672919P5):
a. Abrasive wear and moisture corrosion observed on raceway withdiscoloration of outer ring.
b. Plastic deformation of inner ring with discoloration and abrasive andadhesive wear on raceway.
c. Crack initiation on almost all cage pockets.d. Spalling observed in cage pockets at roller contact.e. High ovality noticed on inner and outer rings.f. Signs of overheating seen with micro-structural changes leading to
deformation.
g. Hardness profiles of outer ring showed low hardness values fromraceway to core rather than from outer diameter to core which
confirms heat generation is high on raceway compared to outer
diameter.
2. Inter-rotor bearing (5-272822P2Y):a. Outer ring and inner ring raceways shows false brinelling marks, spalling
and plastic deformation. Also fretting and micro cracks were observed
on one side of face end of outer ring.
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