AD 75-18-06

75-18-06 BELL: Amendment 39-2345. Applies to Bell Models 47B, 47B-3, 47D, 47D-1, 47E, 47G, 47G-2, and 47H-1 helicopters certificated in all categories that are equipped with a single-row ball bearing, P/N 47-641-146-1 (MRC R4AF4), in the tail rotor pitch control crosshead.

Compliance required within 10 hours' time in service for bearings with more than 40 hours' time in service on the effective date of this AD and prior to attaining 50 hours' time in service for bearings with less than 40 hours' time in service on the effective date of this AD.

To prevent possible failure of the tail rotor pitch control ball bearing due to inadequate lubrication, accomplish the following one-time inspection.

a. Disassemble the tail rotor pitch control crosshead assembly in accordance with Sections VI and VII, Models 47D-1, 47G, and 47G-2 Maintenance and Overhaul Instruction Manual, revised August 15, 1961, or in accordance with equivalent FAA approved procedures to expose the pitchchange bearing.

b. Inspect the bearing, P/N 47-641-146-1 (MRC P/N R4AF4) for grease dust shields.

c. Remove any pitch change bearings with two grease dust shields installed before further flight.

d. Install bearings P/N 47-641-146-1 (MRC P/N R4AF4) with only one grease dust shield installed and assemble and rig the tail rotor controls, in accordance with Sections VI and VII, Models 47D-1, 47G, and 47G-2 Maintenance and Overhaul Instruction Manual, revised August 15, 1961, or in accordance with equivalent FAA approved procedures.

e. This AD does not apply to the obsolete design, single-row ball bearings having a single grease dust shield, Norma Hoffman P/N S1RP and New Departure P/N 7R4AX1C. This AD does not apply to the duplex pitch change bearings, P/N 47-641-131-1.

This amendment becomes effective September 19, 1975.