Bearings – Section 6.2 Assembly Contamination

Section 6.2
Assembly Contamination

Section 6.2.1
Appearance

The bearing appears to have a localized area of wear. The appearance of a foreign material is found on the backside of the bearing. See Figure "Example of Assembly Contamination" .‪

Figure 1. Example of Assembly Contamination

Section 6.2.2
Damage

Damage normally occurs when the bearings are being installed and contamination is introduced to the backside of the bearing, trapping it between the bearings back and the caps. See Figure "Elements of Bearing Failure from Assembly Contamination" .‪

1. Bearing‪	3. Foreign Material‪
2. Housing‪	4. Shaft‪

Figure 2. Elements of Bearing Failure from Assembly Contamination

The contamination creates a high spot on the inside diameter which can cause wear to the bearing. ‪

Section 6.2.3
Possible Causes

Assembly contamination occurs when foreign material enters the engine during engine assembly. It can also occur when an engine is being rebuilt and proper cleaning procedures are not followed, allowing contamination upon assembly. ‪

Section 6.2.4
Recommendation

The recommended maintenance procedures after assembly contamination are:‪

1. Replace bearings.
2. Check all other engine parts for similar wear.
3. Use recommended maintenance practice.