Using Heat and Proper Alignment when Pressing Bearings into Critical Bores
This picture clearly shows the importance of using heat, and proper alignment when pressing bearings into critical bores.
This damage was seen at the overhaul for a P/N: 204-011-406-13 Scissors assembly and clearly shows the metal smear from having the bearings pressed into the bore while misaligned.
In looking at TM 55-1615-226-40 pg 2-6 change 2, the data provided shows that the max allowable damage is 0.002. This damage exceeds that by a large margin.
When working with components like this it's important to use a heat gun to pre-heat the bores and to avoid using any hydraulic pressing device.
A hand arbor press is best used because any misalignment can be felt before any major damage is done to the assembly.
Damage like this is a common occurrence all throughout the Scissors and Sleeve but this area tends to be a bit harder hit than the others. For the sake of your components lifespan, its important that all UH-1 technicians be cognizant of this particular issue to alleviate this type of damage from occurring.
Lesson: Heat it, don't beat it
If you have any questions, do not hesitate to contact me.
David E. Wilson
Valley Aerospace LLC
2618 N OGDEN RD STE 103
MESA, AZ 85215 U.S.A.