Airworthiness Directive · Amendment 39-17541 · Tail rotor gearbox
Eurocopter France Helicopters
This AD applies to Eurocopter AS350C, D, D1, B, BA, B1, B2, and B3; and AS355E, F, F1, F2, N, and NP helicopters, with a tailrotor gearbox (TGB) casing assembly, part number (P/N) 350A33-1090-02 and serial number (S/N) MA47577, MA47585, MA47587 through MA47593, MA47597 through MA47600, MA47602, MA47604, MA47606, MA47610, MA47613, MA47615, MA47617, MA47619 through MA47624, MA47626, MA47628, or MA47631 installed, certificated in any category.
We are adopting a new airworthiness directive (AD) for Eurocopter France (Eurocopter) Model AS350 and AS355 helicopters, to require inspecting for a crack in the control lever attachment yokes, and if needed, replacing the tail rotor gearbox (TGB). This AD is prompted by improper casting of TGB casing assemblies, which may lead to cracking. A crack in the control lever attachment yokes could cause a loss of tail rotor pitch control, and consequently, 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.
Within 100 hours time-in-service:
(1) Remove the control lever, as depicted in Figure 1, item (b), of Eurocopter Alert Service Bulletin (ASB) No. AS350-65.00.46 or No. AS355-65.00.22, both Revision 0 and both dated May 18, 2011, as applicable for your model helicopter.
(2) Strip the paint from the TGB control lever attachment yokes, as depicted in Figure 2, item (z), of the ASB No. AS350-65.00.46 or No. AS355-65.00.22, as applicable to your model helicopter.
(3) Perform a Fluorescent Penetrant Inspection (FPI) in accordance with paragraph 3.B.2 of ASB No. AS350-65.00.46 or No. AS355-65.00.22, as applicable to your model helicopter, on the TGB control lever attachment yokes for a crack. You are only required to follow the actions defined in this ASB paragraph pertaining to the FPI.
(4) If a crack exists, before further flight, replace the TGB with an airworthy TGB.
(5) If there is no crack, clean the inspected area and apply chemical conversion coating (Alodine 1200 or equivalent), Epoxy primer, and top coat paint.
