CH-3 7 Helicopter.

TM 55-4920-201-14

5. Bushing setscrew

Key to figure 4-37:

6. Balancing arbor (2259,

1. Adapter plate assembly

7A050 kit)

(2238, 7HEL051 kit)

7. Arbor scale

2. Blade support blocks

8. Wedge (2247, 7HEL051

3. Tail rotor hub and blade

kit)

assembly

9. Spacers (2203 and 2204,

4. Bushing (2242, 7HEL051

7A050 kit)

kit)

4-62. CH-3 7 Helicopter.

c. Install cone (4), part no. 2297 (7HEL052

4-63. CH-37 Engine Fan Assembly Balance

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

Check, (See figure 4-34).

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

proximately inch. Secure cone in this position by

a. Center engine fan assembly (11, with hub

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

extension upward, on stand table assembly (1,

wrench (8, figure 1-13).

figure 1-13).

d. Install engine fan assembly (5, figure 4-35),

b. Install cone (2, figure 4-34), part no. 2296

with hub extension upward, over balancing arbor

(7HELO52 kit), hub upward, on balancing arbor

(3). Seat fan assembly hub squarely on cone (4)

(4) so that top of cone hub aligns with 16-inch

seat.

position on arbor scale (5). Secure cone in this

e. Install cone (6), part no. 2296 (7HEL052

position by tightening cone setscrew (3) with 1/8-

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

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

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

c. Insert balancing arbor (4, figure 4-34)

this position by tightening cone setscrew (7) with

downward through fan hub, seating cone (2) in

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

upper cone seat of hub.

f, Install 1/2-inch mushroom point on dial

d. Install cone (6), part no. 2297 (7HEL052

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

kit), hub downward, on lower end of balancing

assembly (10) to read track or concentricity

arbor (4), making certain that cone seats firmly in

variations as required. Rotate fan and arbor

bottom cone seat of fan hub.

assembly to determine range of variations.

e. Install spacers (7), part no. 2203, and 2204

g. For track and concentricity tolerances and

(7A050 kit), on balancing arbor (4) under cone (6)

application of corrections refer to applicable

hub.

helicopter manual. (Refer to appendix A).

f. Install hand wheel (26, figure 1-13) bottom

4-65. CH-37 Tail Rotor Assembly Optical

end of arbor, and tighten wheel to clamp spacers,

Trammeling and Balance Check.

cones, and fan hub securely together.

g. Install suspension cable (13, figure 1-13)

4-66. Optical Trammeling. (See figure 4-38).

a. Install -inch-thick wood block on floor

and quick disconnect coupling (10) assembly on

under each of the tubular legs of stand table

suspension rod at top end of arbor, and engage

suepension cable in lifting plate of hydraulic pump

assembly (1, figure 1-13). Do not assemble

assembly.

overhead hoist structure at this time.

h. Hoist entire assembly approximately inch

b. Center fixture assembly (15, figure 4-38)

off work stand. Check to insure that suspended

with blade support blocks upward on stand table

assembly is free from interference with work stand

assembly.

c. Carefully lower tail rotor assembly (2) onto

and other objects, and note the balance condition

fixture assembly (15), aligning blades with fixture

indicated by black indicator disc at top end of the

support blocks (1), studs with clearance holes in

arbor.

fixture arms, and bottom rotor cone seat with

i. For balance tolerance and application of

fixture hub, Insure that blade cuffs rest squarely on

balance corrections refer to applicable helicopter

blade support blocks and that rotor hub is fully

manual. (Refer to appendix A).

seated on fixture hub cone. Disconnect pitch

4-64. CH-37 Engine Fan Assembly Track and

control linkages at blade cuffs, and turn rotor pitch

control rocker arms so that their inner ends are in

Concentricity Check. (See figure 4-35).

the full upward position. (See view A). Disconnect

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

firm support surface. Bolt or clamp base securely to

four tail rotor dampers at adjustment end only.

support surface.

d. Install scope support assembly (3) over top

of balancing arbor (11), insuring definite bot-

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

toming on end of arbor. Secure scope support

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

assembly in this position by tightening scope

firmly bottomed and free to rotate in base.

4-60