Airworthiness Directive · Amendment 39-17580 · Bell Helicopter Textron, Inc. (Bell) Helicopters
Bell Helicopter Textron, Inc. (Bell) Helicopters
This AD applies to Model 204B helicopters with a tail rotor pitch control chain (chain), part number (P/N) 204-001-739-003 or -105, installed, and Model 205A-1 helicopters with a serial number (S/N) 30001 through 30228, certificated in any category.
We are superseding revised Airworthiness Directive (AD) 76-12- 07 for all Bell Model 204B and certain serial-numbered Model 205A-1 helicopters with a certain tail rotor pitch control chain (chain) installed. AD 76-12-07 required visually inspecting the chain to detect a crack in the link segments and, for affected Model 205A-1 helicopters, replacing the chain and cable control system with a push- pull control system. This new AD requires, for Bell Model 204B, inspecting certain chains at specified intervals, revising the inspection procedures, installing a tail rotor cable and chain damper kit (damper kit), and revising the maintenance manual or Instructions for Continued Airworthiness (ICAs) to include the inspection intervals. This new AD also requires, for certain Bell Model 205A-1 helicopters, replacing the chain and cable control system with an airworthy tail rotor push-pull control system kit. This AD was prompted by the rapid growth of a crack leading to premature chain failure. The actions are intended to prevent failure of the chain, loss of tail rotor blade pitch control, and subsequent loss of control of the helicopter.
You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.
(1) For Model 205A-1 helicopters, before further flight, replace the tail rotor chain and cable control system with an airworthy tail rotor push-pull control system by installing an improved tail rotor hub and blade assembly kit, P/N 205-704-040-001 or 205-704-040-103, and then installing a push/pull anti-torque retrofit kit, P/N 205-704-057-001 or 205-704-057-101.
(2) For Model 204B helicopters:
(i) Within 10 hours time-in-service (TIS) and thereafter at intervals not to exceed 10 hours TIS, using a 10-power or higher magnifying glass and a light, visually inspect each of the link segments in the chain for a crack. Also, slowly operate the cockpit anti-torque control pedals during the inspection so that the entire surface area of the chain in contact with the control quill sprocket (sprocket) is visibly accessible and can be inspected. Pay particular attention to the portion of the chain that travels over the sprocket and extends 6 inches to each side of the sprocket.
(A) If there is no cracked or broken link segment, lubricate the chain with a light preservative oil (C-125) or wipe with a cloth dampened in lubricating oil (C-010).
(B) If there is a cracked or broken link segment, before further flight, replace the chain with an airworthy chain.
(ii) Within 50 hours TIS, install a tail rotor cable and chain damper kit, P/N 204-706-130-101, as depicted in Figures 1 through 3, and by following the Accomplishment Instructions, paragraphs 2. through 9., of Bell Alert Service Bulletin (ASB) No. 204-79-7, dated August 21, 1979.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
