Airworthiness Directive · Amendment 39-22100 · Tail rotor drive system
Airbus Helicopters
This AD applies to all Airbus Helicopters Model AS-365N2, AS 365 N3, EC 155B, EC155B1, and SA-365N1 helicopters, certificated in any category.
The FAA is adopting a new airworthiness directive (AD) for all Airbus Helicopters Model AS-365N2, AS 365 N3, EC 155B, EC155B1, and SA- 365N1 helicopters. This AD was prompted by a large amount of critical scale particles found on the tail rotor gearbox (TGB) chip detector magnetic plug during an unscheduled check of the TGB. The particles belonged to the double bearing (pitch control rod bearing) installed inside the TGB. This AD requires repetitive inspections of the TGB chip detector for particles, analyzing any particles collected, performing a double bearing washing, repetitive replacements of certain part- numbered double bearings, and corrective actions if necessary, as specified in a European Union Aviation Safety Agency (EASA) AD, which is incorporated by reference. The FAA is issuing this AD to address the unsafe condition on these products.
Except as specified in paragraph (h) of this AD: Comply with all required actions and compliance times specified in, and in accordance with, European Union Aviation Safety Agency (EASA) AD 2021-0170, dated July 19, 2021 (EASA AD 2021-0170).
(1) Where EASA AD 2021-0170 requires compliance in terms of flight hours (FH), this AD requires using hours time-in-service (TIS).
(2) Where EASA AD 2021-0170 refers to the effective dates specified in paragraphs (h)(2)(i) through (iii) of this AD, this AD requires using the effective date of this AD.
(i) October 28, 2019 (the effective date of EASA AD 2019-0267-E, dated October 25, 2019).
(ii) November 19, 2019 (the effective date of EASA AD 2019-0267R1, dated November 12, 2019, and corrected November 13, 2019).
(iii) The effective date of EASA AD 2021-0170.
(3) Where EASA AD 2021-0170 requires actions during each “after last flight (ALF) of the day inspection” or “ALF,” this AD requires those actions before the first flight of each day.
(4) Where paragraph (7) of EASA AD 2021-0170 specifies “any discrepancy,” for this AD discrepancies include the presence of particles and other conditions such as abrasions, particles that consist of any scale, chip, flake, splinter, M50 particles, magnetic abrasion dust, or other particles other than cotter pin fragments, pieces of lock wire, swarf, or miscellaneous non-metallic waste.
(5) Where paragraph (8) of EASA AD 2021-0170 specifies for Group 2 helicopters, the first replacement of the affected part must be accomplished not later than December 31, 2021, this AD requires, for Group 2 helicopters, the first replacement of the affected part as defined in EASA AD 2021-0170 must be accomplished within 5 months after the effective date of this AD.
(6) Where any work card referenced in the service information referenced in EASA AD 2021-0170 specifies “if there is an anomaly, replace the chip detector,” or “if there is an anomaly, replace the TGB electrical magnetic plug,” for this AD an anomaly may be indicated by the magnetic component of the TGB chip detector or the TGB electrical magnetic plug not being magnetized. If there is an anomaly, this AD requires before further flight, removing from service the TGB chip detector or the TGB electrical magnetic plug as applicable to your model helicopter.
(7) Where any work card referenced in the service information referenced in EASA AD 2021-0170 specifies “make sure that the chip detector is in good condition,” or “make sure that the TGB electrical magnetic plug is in good condition,” as applicable to your model helicopter, for this AD “good condition” is indicated when there are no signs of wear on the locking systems (including wear on the bayonets, and slotted tubes). If there are any signs of wear on the locking systems, this AD requires before further flight, removing from service the TGB chip detector or the TGB magnetic electrical magnetic plug as applicable to your model helicopter.
(8) Where any work card referenced in the service information referenced in EASA AD 2021-0170 specifies “if necessary, replace the O-rings,” this AD requires before further flight, removing any affected O-ring from service.
(9) Where the service information referenced in EASA AD 2021-0170 specifies to return certain parts to the manufacturer, including for repair, this AD does not require returning parts to the manufacturer, however, this AD does require before further flight, repair done in accordance with a method approved by the Manager, General Aviation and Rotorcraft Section, International Validation Branch, FAA; or EASA; or Airbus Helicopters' EASA Design Organization Approval (DOA). If approved by the DOA, the approval must include the DOA-authorized signature.
(10) Where the service information referenced in EASA AD 2021-0170 specifies to remove the TGB as per technical documentation, or remove the concerned module(s), this AD requires before further flight, removing the TGB and replacing it with an airworthy part, or repairing the TGB in accordance with a method approved by the Manager, General Aviation & Rotorcraft Section, International Validation Branch, FAA; or EASA; or Airbus Helicopters' EASA DOA. If approved by the DOA, the approval must include the DOA-authorized signature.
(11) Where the service information referenced in EASA AD 2021-0170 specifies if the collected particles cannot be clearly defined, perform a metallurgical analysis and contact Airbus Helicopters, before continuing flights, this AD does require before further flight, characterization of the particles collected, and performing a metallurgical analysis for any particles collected using a method in accordance with FAA-approved procedures. However, this AD does not require contacting the manufacturer to determine the characterization of the particles collected.
(12) Where the service information or any work card referenced in EASA AD 2021-0170 specifies to do the actions identified in paragraphs (h)(12)(i) through (v) of this AD, this AD does not include those requirements.
(i) Complete Appendix 4.A and 4.B.
(ii) Comply with paragraph 2.D.
(iii) Send all collected particles and metallurgical analysis report to depot level maintenance facility with the concerned module.
(iv) Inform EST using chip detection tracking sheet.
(v) Complete the “Particle Detection” follow up sheet.
(13) Where a work card referenced in the service information referenced in EASA AD 2021-0170 specifies “send all oversized particles for analysis and wait for results before continuing flight,” this AD does not require sending particles for analysis, however this AD does require before further flight, analyzing the particles using a method in accordance with FAA-approved procedures.
(14) This AD does not mandate compliance with the “Remarks” section of EASA AD 2021-0170.
(15) Where paragraph (7) of EASA AD 2021-0170 specifies to accomplish the applicable corrective actions “within the compliance time as identified in the applicable ASB,” this AD requires accomplishing corrective actions before further flight.
(16) Where paragraph (1) of EASA AD 2021-0170 specifies “within the applicable compliance time as identified in the close monitoring and until completion of the close monitoring,” this AD requires a close monitoring compliance time of a total of 25 hours TIS.
Although the service information referenced in EASA AD 2021-0170 specifies to submit certain information to the manufacturer, this AD does not include that requirement.
