63-11 (Engine Driveline) Forward Flex Plate Shimming
NOTE
The engine driveline is shimmed for 0.040 / 0.000 inch
compressive preload. Preload is alleviated by upward movement
of main gearbox during flight.
1. Refer to Figure 53-2. Verify F174-1 support weldment rod end engagement measures
0.93 inch from tube end to rod end centerline (nominal; both sides). Verify 0.2 inch
minimum clearance between F642-1 (engine) shaft weldment and firewall grommet;
verify equal gap concentrically between shaft and F453-1 box assembly hole edges.
Adjust support weldment rod end engagement per Section 53-31 as required.
2. Refer to Figure 63-1. If not previously accomplished, remove hardware securing forward
A947-2 flex plate assembly to F910-1 (main gearbox) yoke and F642-1 (engine) shaft
weldment forward flange. Remove flex plate, and temporarily suppport forward portion
of shaft weldment.
3. Measure flex plate thickness at bonded washers (4 places) to determine average thickness:
(1st place) inch
(2nd place) + inch
(3rd place) + inch
(4th place) + inch
Total = inch
Total ÷ 4 =
inch (Flex plate average thickness)
4. a. Position F910-1 (main gearbox) yoke flange arms and F642-1 (engine) shaft weldment
forward flange arms at 3 o’clock and 9 o’clock positions (horizontal). Measure gap
between arms to determine average gap:
(3 o’clock position) inch
(9 o’clock position) + inch
Total = inch
Total ÷ 2 =
inch (Average gap between flange arms)
b. Rotate F642-1 (engine) shaft weldment 180º, and repeat step a:
(3 o’clock position) inch
(9 o’clock position) + inch
Total = inch
Total ÷ 2 =
inch (Average gap between flange arms)
Page 63.2 Chapter 63 Main Rotor Drive System R66 Maintenance Manual SEP 2012
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