Section IV. OPERATION INSTRUCTIONS - TM-55-4920-201-140069

TM 55-4920-201-14

SECTION

OPERATION

INSTRUCTIONS

4-1. GENERAL

socket over end of arbor suspension rod, and

pressing straight downward on top end of coupling

4-2. The operation instructions included in this

assembly, against moderate spring resistance, until

section cover detailed written procedures and usage

a definite click is felt and heard. (See view A, figure

of the components for the 7A050 and 7HEL053

4-1.) This is the locked position of the coupling.

balance kits in conjunction with components of the

adapter kits (as required) listed in table l-l.

CAUTION

Written procedures are supplemented with ap-

Avoid imparting excessive downward or

propriate application sketches for complete ex-

sidewise pressure on arbor suspension

planations of all operations.

flexible

rod, as damage to the

4-3. Before attempting to perform the operations

suspension element within the arbor

described in this section, make certain the general

may result. Should the coupling fail to

principles of operation of the balancing arbors are

en gage with moderate downward

understood as described in sections I and VII.

and

coupling

pressure, inspect

4-4. For permissable unbalance, tracking, or

suspension rod end for foreign matter

alignment tolerances, refer to applicable propeller

which might cause interference. Parts

or helicopter maintenance manuals. A complete

must be clean.

manual listing is provided in appendix A. Adhere to

4-8. Before disengaging the coupling, be certain

the manual instructions concerning the method of

there is no load (suspended assembly) on the

correcting for conditions of unbalance exceeding

coupling and that the arbor is held so that it will not

the permissable tolerance. Use only the specified

drop. Disengage coupling as follows:

corrective weights and do not exceed the maximum

a. Hold the arbor by the knurled section with

number. Attach and secure all weights properly.

one hand and press straight downward on the

4-5. Since most operations require the use of the

coupling sleeve with the other hand. (See view B,

7A050 work stand and hoist structure, assemble

figure 4-1.)

these components as described in section III.

b. Release coupling sleeve and lift disengaged

4-6. certain of the balance kit components are

coupling off arbor suspension rod.

used in many of the balance check operations

described throughout this section IV. To minimize

CAUTION

repetition of instructions regarding their use and

When installing or removing quick-

operation, genera1 information is included below

disconnect coupling from small

and these instructions shall apply at all times.

balancing arbor, part no. 2516

4-7. Quick-disconnect Couplings. The quick-

(7HEL053 kit), grasp upper suspension

disconnect coupling (10, figure 1-13), normally

rod and decoupler assembly only, so as

assembled to the 3/16-inch diameter suspension

to prevent excessive compression load

cable, is ready for use when removed from the

of the sensitive suspension element.

balancing kit storage case. Install coupling or

(See views C and D, figure 4-1.)

balancing arbor by placing open end of coupling

4-1