Correction Procedures. - TB-1-1520-240-20-1420003

TB 1--1520--240--20--142

Prepare aircraft for safe ground maintenance.

NOTE

As the "staked pin" is commonly referred to as the "elbow pin" by the

field, the term "elbow pin" will be used for the remainder of this

Technical Bulletin.

b. Inspect the strut to determine if they are manufactured by Precision Standard or NORCO. Refer-

ence Figure 58, items 13 and 69, TM 55--1520--240--23P (CH/MH--47D), or Figure 2--42, item 67, TM

1--1520--252--23P (MH--47E). Use the following criteria to determine origin of manufacture.

(1) Elbow Pin --

(a) NORCO -- bucked/staked on both sides, round or protruding head.

(b) Precision Standard -- flush or nearly flush with outer edge of elbow clevis.

(2) Upper strut half front rivets (facing observer in installed position) --

(a) NORCO -- Standard round head rivets, bucked/staked on one (1) side.

(b) Precision Standard -- flush rivets (2), countersunk on both sides.

(3) Strut side opposite pull ring --

(a) NORCO -- countersunk bucked/staked rivets, slight protrusion from surface.

(b) Precision Standard -- countersunk flush rivets.

(4) Part Marking --

(a) NORCO -- if the nonmetallic shields (item 12 or 68, TM 55--1520--240--23P (CH/

MH--47D), or item 66, TM 1--1520--252--23P (MH--47E) are not installed on the strut assembly and the

strut has not been painted, the strut assembly part marking will be visible. The marking includes the

manufacturer name (NORCO, Inc), the manufacturer code, the part number (A297--1), and the NSN.

(b) Precision Standard -- if the nonmetallic shields are not installed, the part marking

(114S2915--61) will be visible..

NOTE

If the elbow pin is not installed, make a thorough search of the entire

tunnel area for the elbow pin and any other debris.

c. If a Precision Standard strut assembly is installed, proceed to paragraph 9.

d. If a NORCO strut assembly is installed, inspect the whole strut assembly for overhaul hardware

integrity --

(1) For any strut assembly without a "bucked" or "staked" elbow pin and/or rivets, or if the ends

of the elbow pin are flush or nearly flush with outer edge of the elbow clevis, proceed to paragraph 9.

(2) If all strut assembly elbow pins and rivets are properly installed, and there is no other damage

to the assembly, the inspection is complete, proceed to paragraph 9c.

Correction Procedures.

CAUTION

WIND TURBULENCE, BOTH NATURALLY OCCURRING AND FROM

NEARBY AIRCRAFT, CAN CAUSE DAMAGE TO THE ACCESS

COVER (S) IF NOT SECURED.

Remove the strut assembly from the aircraft (items 2,3,4,5 and 7 and/or item 63, TM

55--1520--240--23P (CH/MH--47D), or item 61, TM 1--1520--252--23P (MH--47E) and replace with an in-

spected NORCO strut assembly if --

(1) A Precision Standard strut assembly is installed.