CH-34 Engine Fan Assembly Track and Concentricity Check.

TM 55-4920-201-14

4-59. CH-34 Engine Fan Assembly Track and

35), with shroud upward, over balancing arbor (3).

Concentricity Check. (See figure 4-35).

Seat fan assembly hub squarely on cone 14) seat.

a. Set base (2) on surface plate (1) or other

e. Install cone (6), part no. 2227 (7A050

firm and level support surface. Bolt or clamp base

kit), hub upward, over arbor, and seat cone firmly

securely to support surface.

in top cone seat of fan assembly hub. Secure cone in

this position by tightening cone setscrew (7) with 1/8

b. Install lower end of balancing arbor (3) in

inch hex wrench (8, figure 1-13).

base (2) pilot hole. Make certain that arbor is

firmly bottomed and free to rotate in base.

f. Install inch mushroom point on dial

indicator (9, figure 4-35), and adjust height gage

c. Install cone (4), part no. 2228 (7A050

assembly (10) to read track or concentricity

kit), hub downward, on balancing arbor (3) so that

variations as required. Rotate fan and arbor

bottom of cone hub clears top of base (2) by ap-

assembly to determine range of variations.

proximately inch. Secure cone in this position by

tightening cone setscrew (8) with 1/8-inch hex

g. For track and concentricity tolerances and

application of corrections, refer to applicable

helicopter manual. (Refer to appendix A).

d. Install engine fan assembly (5, figure 4-

1. Surface plate

Cone

9. Dial indicator (7HEL055

2. Base (2341, 7HEL055

kit)

Engine fan assembly

10. Height gage assembly

Cone

kit)

3. Balancing arbor (2259,

Cone setscrew

(7HEL055 kit)

7A050 kit)

Cone setscrew

Figure 4-35. Typical Setup for CH-34 and CH-37 Helicopter Engine Fan

Assemblies Track and Concentricity Check.

4-56