AD 74-23-02

74-23-02 BELL: Amendment 39-1999. Applies to Bell Model 204B and 205A-1 helicopters certificated in all categories.

Compliance required as indicated.

To detect cracks in the tail rotor pitch change link segments and to prevent possible failure of the tail rotor pitch change chains accomplish the following repetitive inspections on chains, P/N 205-001-721-1 and 205-001-748-1.

(a) Within five hours time in service after June 7, 1974, unless already accomplished, and thereafter at intervals not to exceed 25 hours time in service from the last inspection, accomplish the following inspections:

(1) Remove the chain or chains from the helicopter in accordance with the applicable maintenance manual.

(2) Clean each chain with solvent and stiff bristle brush and air dry.

(3) Roll each chain into a tight flat disc and inspect the links' outer segments, both sides, for cracks, using a light and a ten-power or higher magnifying glass. Unroll the chain and withteeth up inspect inner segments of the links at the radius between the teeth. Turn each chain over and inspect the opposite side of the link segments.

(4) Replace chains with cracked segments before further flight.

(5) Install chains with uncracked link segments in accordance with the pertinent maintenance manual and rig tail rotor controls in accordance with the pertinent maintenance manual. If 212-010-701 Tail Rotor Hub and Blade Assembly is installed on the Model 205A-1, rig the controls in accordance with the maintenance manual and as specified in Bell Helicopter Company Service Bulletin No. 205-05-74-1, Rev. A, dated June 24, 1974, or later approved revision.

(b) Before the first flight of each day after June 7, 1974, accomplish the following repetitive inspections.

(1) Remove the cover from the chain assembly.

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

(3) Remove chains with cracked segments before further flight in accordance with the applicable maintenance manual.

(4) Install chains with uncracked segments in accordance with the applicable maintenance manual and rig the controls as specified in paragraph (a)(5) of this airworthiness directive.

(c) Replace chains, P/N 205-001-721-1 having manufacturing dates of June 20, 1974, or later etched on the clevis, as follows:

(1) Replace chains with more that 140 hours total time in service on the effective date of this Airworthiness Directive within ten hours time in service.

(2) Replace chains with less than 140 hours total time in service on the effective date of this Airworthiness Directive prior to attaining 150 hours total time in service.

(d) Replace chains, P/N 205-001-721-1 having manufacturing dates prior to June 20, 1974, as follows:

(1) Replace chains with more than 40 hours total time in service on the effective date of this Airworthiness Directive within ten hours time in service.

(2) Replace chains with less than 40 hours total time in service on the effective date of this Airworthiness Directive prior to attaining 50 hours total time in service.

(e) Replace chains, P/N 205-001-748-1, with more than 140 hours total time in service on the effective date of this Airworthiness Directive within ten hours total time in service. Replace chains, P/N 205-001-748-1, with less than 140 hours total time in service on the effective date of this Airworthiness Directive prior to attaining 150 hours total time in service.

The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from themanufacturer may obtain copies upon request to the Service Manager, Bell Helicopter Company, P. O. Box 482, Fort Worth, Texas 76101. These documents may also be examined at the Office of the Regional Counsel, Southwest Region, FAA, 4400 Blue Mound Road, Fort Worth, Texas, and at FAA Headquarters, 800 Independence Avenue, S.W., Washington, D.C. A historical file on this Airworthiness Directive which includes the incorporated material in full is maintained by the FAA at its headquarters in Washington, D. C. and at the FAA Southwest Regional Office, Fort Worth, Texas.

(Bell telefax messages dated May 10, 1974; June 15, 1974; August 2, 1974; and September 25, 1974, pertain to this subject, and Information Letter to all Bell 204B/205A-1 operators, 35:WJD:jge-3152 dated August 12, 1974, also pertains to this subject.)

This supersedes Amendment 39-1963 (39 F.R. 34054), A.D. 74-20-06. This amendment becomes effective November 3, 1974.