AD 72-02-05

72-02-05 BELL: Amdt. 39-1380. Applies to:

Bell Models 47G-2A, 47G-2A-1, 47G-3, 47G-3B, 47G-3B-1, 47G-3B-2, 47G-4, 47G-4A, 47G-5, 47J-2, and 47J-2A helicopters certificated in all categories;

Bell Model 47J helicopters, S/N 1777 and subsequent, certificated in all categories; and

Bell Models 47G, 47G-2, and 47J helicopters, S/N 1420 through 1776, certificated in all categories incorporating Bell Mast Controls Kit No. 47-3411-1, Service Instruction No. 333.

Compliance required as indicated.

To detect possible cracks in the tube surface of control rod assembly, P/N 47-150-255-1, accomplish the following:

(a) Inspect both control tubes within 100 hours time in service after the effective date of this AD, unless already accomplished, in accordance with the procedures listed below and accomplish repetitive inspections at intervals of not more than 1200 hours time in service from the last inspection.

(b) Inspect the complete external surface of the tube for indications of cracks using a dye penetrant or equivalent inspection method.

(c) If crack indications are found polish out and blend all indications into the adjacent areas and reinspect as follows:

(1) Use 240 or 320 grit paper then use 400 grit paper for final polish. Sand only in the lengthwise direction of the tube.

(2) Do not exceed .005 inch deep removal of material. Circumferential (transverse) cleanup of indication is limited to one-fourth of the tube circumference. There is no restriction of the longitudinal length limit.

(3) Reinspect the polished surface of the tube for cracks using a dye penetrant or equivalent inspection method.

(4) If cracks are found remove the cracked tube before further flight.

(d) If no crack indications are found protect any exposed surfaces of the tube using zinc chromate primer or equivalent.

(Bell Helicopter Service Bulletin No. 47-146 dated August 26, 1971 pertains to this subject.)

This amendment becomes effective February 22, 1972.