Install Main Rotor Head and Mast Units

TM 55-1520-238-S

230.7 Install

g. Couple Sling to Crane. Connect crane

Tail

Rotor

Blades. Paragraph

lifting hook to air vehicle sling link (lifting

223.10.

eye). Carefully operate crane winch to re

230.8 Install

Horizontal

Stabilator. Paragraph

move all slack from sling cables.

216.10.

h. Remove Main Rotor Head and Mast Unit

230.9 Install Main Rotor Head and Mast Units. Fig-

from Shipping Carrier. Operate crane

ures 223 and 224.

winch and carefully lift main rotor head and

mast unit straight up and out of the carrier.

Conduct depreservation of coated sur-

WARNING

faces. Hoist the unit high enough to clear

helicopter upper fuselage.

During this procedure, helicopter must

be on a level surface, with landing gear

CAUTION

in normal static condition (not

kneeled). If helicopter is tilted, main ro-

Mixer supports must be centered

tor head and mast unit may slip and

over their mast base holes, and main

swing, causing possible injury of per-

rotor drive shaft must be properly

sonnel or equipment damage.

alined with main transmission drive

a. Remove Main Transmission Access

splines, to prevent damage to criti-

Panels. Release 12 camloc fasteners at

cal mixer and rotor drive compo-

each panel (L200 and R200).

nents.

When lowering main rotor head and

b. Check Drive Shaft Spring. If not pre-

mast units, carefully maintain cen-

viously removed, lift shipping cover from

tral alinement of drive shaft,

top of main transmission. Check position of

installed drive shaft spring and

main rotor drive shaft spring. Spring must

standpipe, and the drive plate open-

be centered over the transmission drive

ing, to prevent parts damage or mis-

shaft hole (fig. 223).

alinement.

c. Install Air Vehicle Sling on Main Rotor

i. Aline Main Rotor Head and Mast Unit

Head. Couple sling fittings to lifting cle-

Over Mast Base. Center the main rotor

vises on main rotor head, in the shipping

drive shaft over drive shaft spring in main

carrier (fig. 223).

transmission, and rotate the unit to aline

d. Aline Lifting Crane Over Main Rotor

right and forward mixer supports over mat-

Head. Center the crane lifting hook over

ing mast base holes.

shipping carrier. Aline lifting hook over

j. Lower Main Rotor Head and Mast Unit

installed air vehicle sling.

Into Place. Slowly lower the unit, and

install forward mixer support bolt and lock

e. Install Mixer Spreader.

washer while the unit is moving down.

TM 1-1520-238-23.

Carefully aline drive shaft splines within

f. Release Main Rotor Head and Mast Unit

main transmission drive splines, and slide

from Shipping Carrier. Open the four

mast flange holes over projecting mast

corner straps securing main rotor head to

base studs. Handtighten mixer support

the carrier frame (fig. 224). Disconnect

bolt.

mixer clevises from carrier turnbuckles. Re-

k. Install 18 New Preload Indicating (PLI)

move mixer support bolts and static mast

washer sets (D22) and Torque 18 Mast

bolts.

Base Nuts.

TM 1-1520-238-23.

l. Install Right Side Mixer Support Bolt

CAUTION

and Lock Washer. Handtighten bolt.

m. Seat and Torque Forward and Right Side

Mixer Support Bolts to 230 to 280 Foot

Air data sensor and attached deicing

Pounds.

housing are shipped in the carrier with

TM 1-1520-238-23. Use mixer bolt torque

the main rotor head and mast unit. If

adapter (item 51, table 22) with 3/4 drive,

not previously unpacked, the sensor

3inch long extension (item 52, table 22).

and housing unit must be removed

Bend lock washer tabs after final retorqu-

from carrier at this point, to prevent

ing.

damage.

Change 5

276.1