AD 76-12-07

76-12-07 BELL: Amendment 39-2640 as amended by Amendment 39-3569. Applies to tail rotor pitch control chains, P/N 204-001-739-3, installed on all Bell Model 204B helicopters and on Bell Model 205A-1 helicopters, S/N 30001 through 30228, certificated in all categories (Airworthiness Docket No. 76-SW-19).

Compliance required for Model 204B helicopters within 25 hours' time in service after July 19, 1976, and thereafter, at intervals not to exceed 25 hours' time in service from the last inspection.

Compliance required for Model 205A-1 helicopters within 10 hours' time in service after October 29, 1979, and thereafter, at intervals not to exceed 10 hours' time in service from the last inspection, until Bell Service Bulletin 205-78-5 dated May 16, 1978, is incorporated per paragraph (f) of this AD.

To detect cracks in the tail rotor pitch change chain link segments and to prevent possible failure of the tail rotor pitch change chains, accomplish the following repetitive inspections on chains, Part Number 204-001-739-3.

(a) Remove the cover, if installed, from the chain assembly.

(b) Inspect each chain assembly for cracks in the link segments using a 10-power or higher magnifying glass. Particular attention should be placed on the portion of the chain that travels over the sprocket and that extends six inches each side of this area or portion.

(c) Remove chains with cracked or broken links or segments before further flight in accordance with the applicable maintenance manual or an equivalent FAA approved procedure.

(d) Install chains with uncracked segments in accordance with the applicable maintenance manual and rig the controls as specified in the applicable maintenance manual or an equivalent FAA approved procedure.

(e) Upon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, Flight Standards Division, FAA, Southwest Region, may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period of the operator if the request contains substantiating data to justify the increase for that operator.

(f) Within 100 hours' time in service after October 29, 1979, modify Bell Model 205A-1 aircraft in accordance with Bell Service Bulletin 205-78-5 dated May 16, 1978, as appropriate. This, in part, requires removal of the chain and cable control system and installation of the push-pull control system in conjunction with use of the Model 212 type of tail rotor.

(g) Aircraft may be flown in accordance with FAR 21.197 to a location where modification required by paragraph (f) of this AD may be accomplished.

(h) Equivalent means of compliance with paragraph (f) of this AD may be approved by the Chief, Engineering and Manufacturing Branch, FAA, Southwest Region, Fort Worth, Texas.

Amendment 39-2640 became effective July 19, 1976. This Amendment 39-3569 becomes effective October 29, 1979.