Airworthiness Directive · Amendment 39-21877 · Tail rotor drive system
Airbus Helicopters
This AD applies to the Airbus Helicopters model helicopters, certificated in any category, as identified in paragraphs (c)(1) through (3) of this AD.
(1) Model AS-365N2, AS 365 N3, and SA-365N1, all serial numbers on which Airbus Helicopters modification 0763B64 has been embodied, except those on which Airbus Helicopters modification 0763C81 has been embodied.
(2) Model SA-365C1, SA-365C2, and SA-365N, all serial numbers on which Airbus Helicopters modification 0763B64 has been embodied.
(3) Model EC 155B and EC155B1, all serial numbers, except those on which Airbus Helicopters modification 0763C81 has been embodied.
The FAA is superseding Airworthiness Directive (AD) 2020-21-01 for certain Airbus Helicopters Model AS-365N2, AS 365N3, EC 155B, EC155B1, and SA-365N1 helicopters. AD 2020-21-01 required 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 MGB T/R drive flange. This AD continues to require modifying the MGB T/R drive flange installation, and includes additional helicopters in the applicability for the required actions. The FAA is issuing this AD to address the unsafe condition on these products.
This paragraph restates the requirements of paragraph (e) of AD 2020-21-01 with no changes. Within 600 hours time-in-service after November 12, 2020 (the effective date of AD 2020-21-01):
(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, Revision 1); 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, Revision 1, and by following the Accomplishment Instructions, paragraph 3.B.2.b, of ASB AS365-63.00.19, Revision 1.
(2) For Model EC 155B and EC155B1 helicopters with modification 0763B64 embodied:
(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, Revision 1); 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, Revision 1, and by following the Accomplishment Instructions, paragraph 3.B.2.b, of ASB EC155-63A013, Revision 1.
Note 1 to paragraph (g)(2)(ii): ASB EC155-63A013, Revision 1 refers to the “aft output stop” as “rear output stop.”
For Model SA-365C1, SA-365C2, and SA-365N helicopters; and Model EC 155B and EC155B1 helicopters without modification 0763B64 embodied: Within 600 hours time-in-service after the effective date of this AD, modify the MGB T/R drive flange installation, in accordance with paragraph 3.B.2., “Procedure,” of the Accomplishment Instructions of the applicable service information specified in paragraphs (h)(1) through (3) of this AD, except as specified in paragraph (i) of this AD.
(1) Airbus Helicopters ASB SA365-65.52, Revision 1, dated July 22, 2020.
(2) Airbus Helicopters ASB AS365-63.00.26, Revision 0, dated July 22, 2020.
(3) ASB EC155-63A013, Revision 1.
Where the service information identified in paragraph (h) of this AD specifies to discard certain parts, this AD requires removing those parts from service.
