TB 1-1520-238-30-20
4. SUMMARY.
4.1. There are reports of chafing/contact between the Intermediate Gear Box (IGB) Diffuser P/N
7-511332020-1 and the upper surface of the tailboom skin. This condition may exist on all AH-64 D-Model
and ECP 1315 A-Model helicopters. Additionally, there have been reports of cracking developing common
to the upper leg or around the cutout for the control rod. Failures of the IGB fairing rubber strips have also
been reported from fielded D-Model or ECP 1315 A-Models.
5. PURPOSE.
5.1. This Technical Bulletin (TB) provides procedures for modifying the P/N 7-511332020-1 IGB Diffuser,
adding additional clearance and fabrication of a gusset that will attach to the upper support leg. It also
contains repair procedures for the tailboom if a chafing condition is present. Instructions are provided for
modifying the IGB Fairing from an A-model (basic) configuration to a D-model, or ECP 1315 A-model
configuration if necessary. It also provides procedures to modify an IGB Fairing (either D-model or ECP 1315
configuration) to improve the life of the fairing.
6. END ITEMS AFFECTED. All Army AH-64 A/D Apache aircraft.
7. ASSEMBLIES COMPONENTS AFFECTED:
Nomenclature
Part Number
National Stock Number
Tailboom Assembly A-model
7-311114000
NSN unavailable
Tailboom Assembly A-model (ECP 1315)
7-311114000-601
NSN unavailable
Tailboom Assembly D-model
7-311114000-601
NSN unavailable
Tailboom Assembly D-model
7-311114000-605
NSN unavailable
8. PARTS AFFECTED: This listing encompasses US Army AH-64A/D components.
Nomenclature
Part Number
National Stock Number
IGB Diffuser A-model
7-311332020
IGB Diffuser A-model (ECP 1315)
7-511332020-1
IGB Diffuser D-model
7-511332020-1
IGB Fairing LHS
7-311122620-3
NSN unavailable
IGB Fairing RHS
7-311122620-5
NSN unavailable
IGB Fairing, LHS, A-model
7-311122620-47
NSN not applicable
IGB Fairing, RHS, A-model
7-311122620-48
NSN not applicable
9. APPLICATION:
9.1. Category of maintenance: TBD.
9.2. Time required to inspect and rework.
9.2.1 Approximately: 0.5 hours using 1 person to inspect.
9.2.2 Approximately: Time to rework dependent on discrepancy noted.
10. PUBLICATIONS WHICH REQUIRE CHANGE AS A RESULT OF THIS TECHNICAL BULLETIN:
10.1. TM 1-1520-238-23 Aviation Unit and Intermediate Maintenance Manual for the AH-64A.
10.2. ETM 1-1520-238-23 Electronic Aviation Unit and Intermediate Maintenance Manual for the AH-64A.
10.3. IETM 1-1520-251-Longbow/Apache Interactive Electronic Aviation Unit and Intermediate Mainte-
nance Manual for the AH-64D.
10.4. TM 1-1520-238-23P
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