Airworthiness Directive · Amendment 39-21274 · Tail rotor drive system
Airbus Helicopters
Superseded. A later AD replaced this one: AD 2021-26-18. Comply with the one in force.
This AD applies to Airbus Helicopters Model AS-365N2, AS 365N3, EC 155B, EC155B1, and SA-365N1 helicopters, certificated in any category, with modification 0763B64 installed, except those with modification 0763C81.
The FAA is adopting a new airworthiness directive (AD) for certain Airbus Helicopters Model AS-365N2, AS 365N3, EC 155B, EC155B1, and SA-365N1 helicopters. This AD requires modifying the main gearbox (MGB) tail rotor (T/R) drive flange installation. This AD was prompted by several reported occurrences of loss of tightening torque of the Shur-Lok nut, which serves as a retainer of the T/R drive flange. The actions of this AD are intended to address an unsafe condition on these products.
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 600 hours time-in-service:
(1) For Model AS-365N2, AS 365N3, and SA-365N1 helicopters:
(i) Without removing the tail drive shaft flange (a), remove the sliding flange (b) from the flexible coupling (c) as shown in Detail “B” of Figure 1, PRE MOD, of Airbus Helicopters Alert Service Bulletin (ASB) No. AS365-63.00.19, Revision 1, dated January 31, 2019 (ASB AS365-63.00.19); replace the 3 bolts (d) and remove from service the 3 washers (e).
(ii) Install the sliding flange (b) with aft output stop (1) part number (P/N) 365A32-7836-20 as shown in Detail “B” of Figure 1, POST MOD, of ASB AS365-63.00.19 and by following the Accomplishment Instructions, paragraph 3.B.2.b, of ASB AS365-63.00.19.
(2) For Model EC 155B and EC155B1 helicopters:
(i) Without removing the Shur-Lok nut (a), remove the sliding flange (b) from the flexible coupling (c) as shown in Detail “B” of Figure 1, PRE MOD, of Airbus Helicopters ASB No. EC155-63A013, Revision 1, dated January 31, 2019 (ASB EC155-63A013); replace the 3 bolts (d) and remove from service the 3 washers (e).
(ii) Install the sliding flange (b) with aft output stop (1) P/N 365A32-7836-20 as shown in Detail “B” of Figure 1, POST MOD, of ASB EC155-63A013 and by following the Accomplishment Instructions, paragraph 3.B.2.b, of ASB EC155-63A013.
Note 1 to paragraph (e)(2)(ii): ASB EC155-63A013 refers to the “aft output stop” as “rear output stop.”
