Summary of Problem - TB-1-1520-237-20-2460002

TB 1--1520--237--20--246

d. Maintenance Trainers (Category A and B). Same as paragraph 1.a..

e. Component/Parts in Stock at All Levels (Depot Level and Others), including War Reserves. Upon

receipt of this message, Depot and Materiel Activity Commanders will ensure the Materiel Condition Tags of

all items in all condition codes listed in paragraphs 6 and 7 are annotated to read: "TB 1-1520-237-20-246,

Inspection of Control Rod Jamnuts, not complied with.

(1) Wholesale Stock. Report receipt of this TB IAW paragraph 14.b.(1) NLT 12 February 2002.

Upon receipt of this TB, depot and materiel activity commanders will ensure all items in condition codes //A//,

//B//, //C//, //D//, and //E//, listed in para 7, are placed in condition code //J// and tagged with a Suspended

Tag/Label - Materiel, DD form 1575/DD Form 1575--1. Do not remove original condition tags. Report com-

pliance with this message IAW paragraph 14.b.(2) NLT 22 February 2002.

(2) Retail Stock. Report receipt of this TB IAW paragraph 14.c.(1) NLT 12 February 2002. Upon

receipt of this TB, commanders and facility managers maintaining retail stock at installation level and below

shall contact the supported aviation unit to perform the procedures required IAW para 8 and 9 on suspect

materiel. Dispose of discrepant materiel IAW para 10.. Report compliance with this TB IAW para 14.c.(2)

NLT 22 February 2002.

f. Components/Parts in Work (Depot Level and Others). Depot And other maintenance activity com-

manders will ensure items listed in para 6 and 7 are not issued until they are in compliance with this TB.

2. Task/Inspection Suspense Date. Complete the inspection requirements of paragraph 8 within the next

10 flight hours, but NLT 22 February, 2002 and report IAW paragraph 14.a.(2) NLT 26 February 2002.

3. TAMMS Reporting Compliance Suspense Date.

Report compliance IAW paragraph 14.a.(1) NLT

15 February 2002.

Summary of Problem -

a. During a recent UH-60 main rotor rigging procedure, adjustments were being made to the pitch/trim

input control pushrod. During final installation, the rod end jamnut (P/N 70400-02267-102) broke in half while

being torqued. Subsequent analysis revealed the threads were improperly machined (undersize). Analysis

also revealed the specimen nut displayed properties consistent with 7075-T6 aluminum, and nuts manufac-

tured by the vendor were not coated with primer as required. During its first installation, the specimen nut

may have had excessive force applied as a result of the non-conforming threads. Although the primary cause

in this failure was static overload, 7075-T6 aluminum is also prone to stress corrosion cracking while under

preload.

b. Manpower/downtime and funding impacts -- See paragraph 12.

The purpose of this TB is to -

(1) Conduct an initial and recurring inspection for cracked control rod jamnuts.

(2) Require a publications change for the preventive maintenance services,10 hr/14 day (30

hr/42 day) inspection checklist (PMS-1) for affected assemblies.

(3) Purge from retail and wholesale stock all nuts, plain hexagon, p/n 70400-02267-102,

manufactured under cage code 1BER9.

End Items to be inspected. All H-60 aircraft.

Assembly Components to be Inspected.

ACFT

NOMENCLATURE

PART NO.

NSN

Rod Assy, Adj, Coll.

70400-02264-059

1680-01-159-4618

All

Rod Assy, Adj, Longit

70400-02264-058

1680-01-159-4614

ALL

Rod Assy, Adj, Yaw

70400-02264-060

3040-01-159-4621