Airworthiness Directive · Amendment 39-21593 · Main rotor drive system
Airbus Helicopters
This airworthiness directive (AD) applies to Airbus Helicopters Model AS-365N2, AS 365 N3, SA-365N, and SA-365N1 helicopters, certificated in any category.
The FAA is adopting a new airworthiness directive (AD) for Airbus Helicopters Model AS-365N2, AS 365 N3, SA-365N, and SA-365N1 helicopters. This AD requires replacing the main gearbox (MGB), or as an alternative, replacing the epicyclic reduction gear module for certain serial numbered planet gear assemblies installed on the MGB. This AD also requires inspecting the MGB magnetic plugs and oil filter for particles. Depending on the outcome of the inspections, this AD requires further inspections and replacing certain parts. This AD was prompted by failure of an MGB second stage planet gear. The FAA is issuing this AD to correct 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.
(1) For helicopters with at least one Type X planet gear assembly with a serial number (S/N) listed in Appendix 4.A. of Airbus Helicopters Alert Service Bulletin ASB No. AS365-05.00.78, Revision 3, dated March 2, 2018 (ASB AS365-05.00.78) installed on the main gearbox (MGB), before further flight, replace the MGB or as an alternative to replacing an affected MGB, replace the epicyclic reduction gear module Post Modification (MOD) 0763C52 in the affected MGB in accordance with paragraph 3.B.2 of the Accomplishment Instructions of Airbus Helicopters Service Bulletin SB No. AS365-63.00.21, Revision 3, dated July 26, 2018 (SB AS365-63.00.21), except you are not required to contact Airbus Helicopters.
(2) For helicopters without any Type X planet gear assembly installed but with at least one Type Y planet gear assembly with an S/N listed in Appendix 4.B. of ASB AS365-05.00.78 installed on the MGB, within 300 hours time-in-service (TIS), or before any gear accumulates 1,300 hours TIS since new, whichever occurs first, replace the MGB or as an alternative to replacing the MGB, replace the epicyclic reduction gear module MOD 0763C52 in the affected MGB in accordance with paragraphs 3.B.2. of the Accomplishment Instructions of SB AS365-63.00.21, except you are not required to contact Airbus Helicopters.
(3) As of the effective date of this AD, do not install an MGB with a Type X or Type Y gear assembly with an S/N listed in Appendix 4.A. or 4.B. of ASB AS365-05.00.78 installed on the MGB, on any helicopter.
(4) For all helicopters, within 10 hours TIS and thereafter before the first flight of the day or at intervals not to exceed 10 hours TIS, whichever occurs first, inspect the lower MGB magnetic plugs for particles.
(i) If there are particles that consist of any scale, flake, or splinter, or particles other than cotter pin fragments, pieces of lock wire, swarf, abrasion, or miscellaneous non-metallic waste and the planet gear assembly has logged less than 50 hours TIS since new, inspect the MGB plugs for particles before further flight and inspect the oil filter for particles within 5 hours TIS. Thereafter, for 25 hours TIS, continue to inspect the MGB plugs for particles before each flight, inspect the oil filter for particles at intervals not to exceed 5 hours TIS, and perform the actions required by paragraphs (f)(4)(ii)(A) through (B) of this AD.
(ii) If there are particles that consist of any scale, flake, or splinter, or particles other than cotter pin fragments, pieces of lock wire, swarf, abrasion, or miscellaneous non-metallic waste and the planet gear assembly has logged more than 50 hours TIS since new, inspect the cumulative surface area of the particles collected from both the magnetic plug and the oil filter, since last MGB overhaul or since new if no overhaul has been performed.
(A) If the total surface area of the particles is less than 3 mm 2, examine the particles with largest surface area (S), longest particle length (L) and thickest particles (e).
(1) If largest surface area (S) of a particle is less than 1 mm 2, the L is less than 1.5 mm, and the e is less than 0.2 mm, inspect the MGB plugs for particles before further flight and inspect the oil filter for particles within 5 hours TIS. Thereafter, for 25 hours TIS, continue to inspect the MGB plugs for particles before each flight, inspect the oil filter for particles at intervals not to exceed 5 hours TIS, and perform the actions required by paragraphs (f)(4)(ii)(A) through (B) of this AD.
(2) If largest particle size (S) is greater than 1 mm 2, the L is greater than 1.5 mm, or the e is greater than 0.2 mm, perform a metallurgical analysis for any 16NCD13 particles using a method in accordance with FAA-approved procedures.
(3) If there are any 16NCD13 particles, replace the MGB with an airworthy MGB.
(4) If there are no 16NCD13 particles, inspect the MGB plugs for particles before further flight and inspect the oil filter for particles within 5 hours TIS. Thereafter, for 25 hours TIS, continue to inspect the MGB plugs for particles before each flight, inspect the oil filter for particles at intervals not to exceed 5 hours TIS, and perform the actions required by paragraphs (f)(4)(ii)(A) through (B) of this AD.
(B) If the total surface area of collected particles is greater than or equal to 3 mm 2, before further flight, perform a metallurgical analysis for any 6NCD13 particles using a method in accordance with FAA-approved procedures.
(1) If there are any 16NCD13 particles, before further flight, replace the MGB with an airworthy MGB.
(2) If there are no 16NCD13 particles, inspect the MGB plugs for particles before further flight and inspect the oil filter for particles within 5 hours TIS. Thereafter, for 25 hours TIS, continue to inspect the MGB plugs for particles before each flight, inspect the oil filter for particles at intervals not to exceed 5 hours TIS, and perform the actions required by paragraphs (f)(4)(ii)(A) through (B) of this AD.
