AD 70-14-01

70-14-01 BELL: Amdt. 39-1022 as amended by Amendment 39-1065. Applies to all Bell Model 47D-1, 47G, 47G-2, and 47H-1 helicopters certificated in all categories and to any other helicopters equipped with duplex pitch change bearings, P/N 47-641-131-1.

Compliance required as indicated.

To prevent possible failure of tail rotor duplex pitch change bearing and to correct any improper installation of the duplex bearing and delta hinge bolts:

(a) Inspect all duplex pitch change bearings within the next 50 hours time in service after the effective date of this AD, unless already accomplished, as follows:

(1) Remove tail rotor assembly.

(2) Remove and disassemble the tail rotor drive head assembly to expose the duplex bearings and guide sleeve, P/N 47-641-040 or 47-641-130.

(3) Inspect the outside surface of the guide sleeve for scoring.

(4) Inspect the duplex bearing for roughness.

(5) Replace the duplex bearing before further flight as specified in subparagraphs (b)(3) and (4) if the guide sleeve is scored or if the bearing is rough.

(6) Install the tail rotor assembly and check rigging and tracking as described in subparagraph (b)(5).

(b) Remove and replace duplex pitch change bearings with 450 or more hours time in service on the effective date of this AD within the next 150 hours time in service, as follows:

(1) Remove tail rotor assembly,

(2) Remove and disassemble the tail rotor drive head assembly,

(3) Assemble and install the tail rotor drive head assembly, using a new duplex bearing, P/N 47-641-131-1, in accordance with the procedures specified in Paragraphs 6.63(j) and (k) in the Model 47D-1, 47G, and 47G-2 Maintenance and Overhaul Instruction Manual, as revised August 15, 1961, or in accordance with FAA approved equivalent procedures.

(4) Lubricate the bearing and sleeve with grease, MIL-G-25537 or equivalent.

(5) Install the tail rotor assembly and check rigging and tracking in accordance with the procedures specified in Paragraphs 6-17(a) through (h) or 6-18(a) through (g) of the appropriate manual or in accordance with FAA approved equivalent procedures.

(c) Remove and replace duplex pitch change bearings with less than 450 hours time in service on the effective date of this AD prior to accumulating 600 hours time in service, in accordance with the procedures described in subparagraphs (b)(1) through (5) above.

(d) Remove and replace all replacement duplex pitch change bearings prior to accumulating 600 hours time in service.

Amendment 39-1022 effective August 10, 1970. This Amendment (39-1065) becomes effective August 17, 1970.