Airworthiness Directive · Amendment 39-16678 · Agusta S.p.A. Model A109A and A109AII Helicopters
Agusta S.p.A. Model A109A and A109AII Helicopters
Models A109A and A109A II helicopters, with tail rotor special hub plug (hub plug), part number (P/N) 109-0133-18-103; certificated in any category.
This amendment adopts a new airworthiness directive (AD) for the specified Agusta S.p.A. (Agusta) helicopters with a certain tail rotor special hub plug (hub plug) installed. This action requires a one-time inspection to determine the tightening torque value of the hub plug, and depending on the inspection results, replacing certain parts or disassembling the tail rotor hub and blades assembly and inspecting for damage. If the tightening torque value is between 600 kgcm and 700 kgcm, the lock washer and o-ring must be replaced with airworthy parts, and no further action is required. If the tightening torque value is greater than 700 kgcm, the hub plug must be replaced with an airworthy part. Torque the new hub plug to the specified tightening torque between 600 and 700 kgcm. If the tightening torque value of the hub plug is less than 600 kgcm, the tail rotor hub and blades assembly must be disassembled and inspected for damage. If a part is found that is outside allowable damage tolerances, that part must be replaced with an airworthy part. This amendment is prompted by the discovery that a wrong tightening torque value for the hub plug was contained in a revision to the helicopter maintenance manual. The actions specified in this AD are intended to detect an improperly torqued hub plug that could lead to tail rotor failure and subsequent loss of control of the helicopter.
To detect an improperly torqued hub plug that could lead to tail rotor failure and subsequent loss of control of the helicopter, accomplish the following:
(a) Determine if the tightening torque value of the hub plug is between 600 kgcm and 700 kgcm.
(b) If the tightening torque value of the hub plug is between 600 kgcm and 700 kgcm, remove and replace the lock washer, P/N 109-0133-17-103, and the o-ring, P/N MS29561-119, with airworthy parts.
(c) If the tightening torque value of the hub plug is greater than 700 kgcm, remove and replace the hub plug, P/N 109-0133-18-103 with an airworthy part. Torque the hub plug to the specified tightening torque between 600 and 700 kgcm.
(d) If the tightening torque value of the hub plug is less than the 600 kgcm, do the following:
(1) Remove the tail rotor hub and blades assembly, P/N 109-0131-02 (all dash numbers).
(2) Inspect the broaching faces (splined area “F”) and bearing faces (area “D”) of the trunnion, P/N 109-0131-05 or 109-8131-33, for spalling, fretting, or wear by reference to Figure 2 of Agusta Mandatory Alert Bollettino Tecnico No. 109-132, dated October 22, 2010 (BT). If there is spalling, fretting, or wear that is outside allowable damage tolerances specified in Figure 2 of the BT, replace the trunnion with an airworthy trunnion.
(3) Inspect the hub plug, the spacers, P/N 109-0133-16-103 and 109-0130-89-1, and the static stop, P/N 109-0130-27-5, for spalling, fretting, wear, or corrosion. If there is any spalling, fretting, wear, or corrosion, replace the part with an airworthy part.
(4) Inspect the broaching area “H” of the output drive shaft, P/N 109-0445-08-3 or 109-0445-08-7, of the tail rotor gearbox assembly, P/N 109-0440-01, for fretting, wear, or other damage by referring to Figure 3 of the BT. If there is any fretting, wear, or other damage of 0.07 mm or more in depth between loaded and unloaded areas, replace the output drive shaft with an airworthy output drive shaft.
(5) Reinstall the tail rotor hub and blade assembly, and tighten the torque on the hub plug to between 600 kgcm and 700 kgcm.
(6) Accomplish a flap axis play inspection, a flap hinge friction inspection, and a tail rotor dynamic balance.
(e) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Contact the Manager, Safety Management Group, ATTN: DOT/FAA Southwest Region, Sharon Miles, Rotorcraft Directorate, Regulations and Policy Group, ASW-111, 2601 Meacham Blvd., Fort Worth, Texas 76137; telephone: (817) 222-5122; fax: (817) 222-5961, for information about previously approved alternative methods of compliance.
(f) The Joint Aircraft System/Component (JASC) Code is 6500: Tail rotor drive system.
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.
Aircraft
