Airworthiness Directive · Amendment 39-18712 · Tail rotor gearbox
Airbus Helicopters (Previously Eurocopter France) Helicopters
Superseded. A later AD replaced this one: AD 2021-05-05. Comply with the one in force.
This AD applies to Model SA-365N1, AS-365N2, AS 365 N3, SA-366G1, EC 155B, and EC155B1 helicopters with a tail rotor gearbox (TGB) pitch control rod assembly double bearing (bearing) part number (P/N) 704A33-651-093 or P/N 704A33-651-104 installed, certificated in any category.
We are superseding Airworthiness Directive (AD) 2007-25-08 for Eurocopter France (now Airbus Helicopters) Model SA-365N1, AS-365N2, AS 365 N3, SA-366G1, EC 155B, and EC155B1 helicopters. AD 2007-25-08 required checking the tail rotor gearbox (TGB) oil, inspecting the magnetic plug, and either replacing the TGB or performing additional inspections. This AD was prompted by reports of new occurrences of loss of yaw control due to failure of the control rod bearing. This AD requires checking the TGB oil level and replacing the bearing with a new part-numbered bearing. These actions are intended to detect and prevent damage to the bearing resulting in end play, loss of tail rotor 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) Before further flight and thereafter at the following intervals, check the TGB oil level:
(i) For Model SA-365N1, AS-365N2, and AS 365 N3 helicopters, at intervals not to exceed 10 hours time-in-service (TIS).
(ii) For Model SA366G1 helicopters, before the first flight of each day.
(iii) For Model EC 155B and EC155B1 helicopters, at intervals not to exceed 15 hours TIS.
(iv) The actions required by paragraph (f)(1) of this AD may be performed by the owner/operator (pilot) holding at least a private pilot certificate and must be entered into the aircraft records showing compliance with this AD in accordance with 14 CFR 43.9 (a)(1) through (4) and 14 CFR 91.417(a)(2)(v). The record must be maintained as required by 14 CFR 91.417, 121.380, or 135.439.
(2) If the oil level is not at maximum, before further flight, a qualified mechanic must fill it to the maximum level.
(3) Within 15 hours TIS, replace the bearing P/N 704A33-651-093 or P/N 704A33-651-104 with a bearing P/N 704A33-651-245 or P/N 704A33-651-246.
(4) Do not install bearing P/N 704A33-651-093 or P/N 704A33-651-104 on any helicopter.
