Airworthiness Directive · Amendment 39-17305 · Main rotor gearbox
Eurocopter France Helicopters
This AD applies to Eurocopter France (Eurocopter) Model SA-365N, SA-365N1, AS-365N2, AS 365 N3, EC 155B, EC155B1, SA-366G1, SA-365C, SA-365C1, and SA-365C2 helicopters, certificated in any category.
We are adopting a new airworthiness directive (AD) for all Eurocopter France (Eurocopter) Model SA-365N, SA-365N1, AS-365N2, AS 365 N3, EC 155B, EC155B1, SA-365C, SA-365C1, SA-365C2, and SA-366G1 helicopters. This AD requires inspecting portions of the main gearbox (MGB) for the presence of sealing compound and corrosion. This AD was prompted by reports of corrosion on the main MGB casing lower area between the two servo-control anchoring fitting attachment ribs. An investigation determined that the corrosion was associated with sealing compound on the lower part of the fitting/casing attachment. The actions in this AD are intended to detect corrosion on the MGB casing, which could lead to a crack, failure of the MGB, 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) Within 30 hours time-in-service, inspect the lower parts of the MGB servo-control anchoring fittings (anchor fittings) for sealing compound, referring to Figure 1 of Eurocopter Emergency Alert Service Bulletin No. 63.00.17 (for Models SA-365N, SA-365N1, AS-365N2 and AS 365 N3); No. 63A011 (for Models EC 155B and EC155B1); No. 65.03 (for Model SA-366G1); and No. 65.47 (for Models SA-365C, SA-365C1, and SA-365C2), Revision 0, dated May 7, 2008 (EASB).
Note 1 to paragraph (e)(1): The Eurocopter EASB is one document with multiple EASB numbers, each applicable to different base model Eurocopter helicopters.
(2) If there is sealing compound on the lower part of an MGB anchor fitting, remove the sealing compound and inspect for corrosion in the lower area of the MGB casing.
(i) If there is corrosion, before further flight, repair the corrosion area.
(ii) If there is no corrosion, apply touch up protective treatment, if required, and renew the bead of any damaged sealing compound in the upper part of the anchor fitting.
