TC APPROVED
BHT-407-MM-1
4-00-00
2 MAY 2019
Rev. 47
Page 17
Export Classification C, ECCN EAR99
Figure 4-3. Tail Rotor Hanger Bearing — Inspection (Sheet 2 of 2)
407_MM_04_0007_c01
It is not necessary to disconnect the forward or aft short shaft or any of the tail
rotor driveshaft segment assemblies in order to perform this inspection.
Remove the cowlings and covers to get access to the oil cooler blower assembly
and the tail rotor driveshaft segment assemblies; see Chapter 53.
OPERATING BEARINGS ARE HOT. IF THIS TEST IS DONE A SHORT TIME AFTER
SHUTDOWN, EXERCISE CAUTION TO AVOID BURNS.
Inspect the bearing seal for tears. Bearings 406-040-339-ALL have
a brown elastomer seal.
Slowly rotate the main rotor to turn the tail rotor driveshaft system. Check for
indications of bearing roughness at each bearing location, six places, by placing a
hand on the bearing hanger as the tail rotor driveshaft is turning.
Examine the accumulated grease that has been expelled from around the bearing
seal during operation for a color change.
Bearings 406-040-339-ALL use Mobil 28 grease that is
normally red-purple but turns black when the bearing is damaged.
Also, visually inspect the expelled grease that has accumulated for metal particles.
If there is no indication of roughness, the expelled grease is not black, there are no metal particles
suspended in the expelled grease, and the bearing seal is intact, return the helicopter to service.
If the bearing seal is torn, the expelled grease is black, or there are metal
particles suspended in the expelled grease, then replace the bearing; see Chapter 65.
If the bearing turns rough, remove the affected shaft and rotate the bearing
manually to confirm the rough operation. Replace a rough turning bearing.
Notify Product Support Engineering that a damaged bearing has been found.
1.
NOTES
3
WARNING
2.
6.
7.
8.
9.
4
5
Lubricate the bearings.
10.
For bearing 406-040-339-ALL brown seal, use only Mobil 28.
BEARING 406-040-339-ALL, BROWN ELASTOMER SEAL MUST BE GREASED WITH MOBIL 28 ONLY.
DO NOT MIX WITH ANY OTHER GREASE. USE A SEPARATE GREASE GUN. IF THE BEARING IS
CONTAMINATED WITH ANY OTHER GREASE, THE BEARING MUST BE SCRAPPED.
CAUTION
