Airworthiness Directive · Amendment 39-22024 · Tail rotor drive system
Airbus Helicopters
This AD applies to Airbus Helicopters Model SA-365N1, AS-365N2, AS 365 N3, SA-366G1, EC 155B, and EC155B1 helicopters, all serial numbers, certificated in any category.
The FAA is superseding airworthiness directive (AD) for 2021- 05-05 which applied to all Airbus Helicopters Model SA-365N1, AS-365N2, AS 365 N3, SA-366G1, EC 155B, and EC155B1 helicopters. AD 2021-05-05 required modifying the helicopter by replacing the tail rotor gearbox (TGB) control shaft guide bushes; repetitive inspections (checks) of the oil level of the TGB and, if necessary, filling the oil to the maximum level; repetitive inspections of the TGB magnetic plug and corrective actions if necessary; repetitive replacements of a certain control rod double bearing (bearing); and modifying the helicopter by replacing the TGB. This AD was prompted by a report where during a landing phase, a helicopter lost tail rotor pitch control, which was caused by significant damage to the TGB bearing. This AD retains some of the requirements of AD 2021-05-05, and reduces the intervals of the magnetic plug inspection, revises the corrective actions if particles are detected, and revises the compliance time for replacement of the affected part, 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.
(1) For Model SA-365N1, AS-365N2, AS 365 N3, EC 155B, and EC155B1 helicopters: 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 2021-0171, dated July 19, 2021 (EASA AD 2021-0171).
(2) For Model SA-366G1 helicopters: Before further flight after the effective date of this AD, accomplish the actions (e.g., modify the helicopter by replacing the TGB control shaft guide bushes, do repetitive inspections of the TGB magnetic plug and applicable corrective actions; do repetitive replacements of a certain bearing; and modify the helicopter by replacing the TGB) specified in paragraph (g)(l) of this AD using a method approved by the FAA.
(1) Where EASA AD 2021-0171 refers to its effective date, this AD requires using the effective date of this AD.
(2) Where EASA AD 2021-0171 refers to flight hours (FH), this AD requires using hours time-in-service.
(3) Where EASA AD 2021-0171 requires action after the last flight of the day or “ALF,” this AD requires those actions before the first flight of the day.
(4) This AD does not mandate compliance with the “Remarks” section of EASA AD 2021-0171.
(5) Where paragraph (2) of EASA AD 2021-0171 requires inspections (checks) to be done “in accordance with the instructions of Paragraph 3.B.1 of the applicable inspection ASB,” for this AD, those instructions are for reference only and are not required for the actions in paragraph (2) of EASA AD 2021-0171. The inspections (checks) required by paragraph (2) of EASA AD 2021-0171 may be performed by the owner/operator (pilot) holding at least a private pilot certificate and must be entered into the aircraft records showing compliance with this AD in accordance with 14 CFR 43.9 (a)(1) through (4) and 14 CFR 91.417(a)(2)(v). The record must be maintained as required by 14 CFR 91.417 or 135.439.
(6) Where paragraph (5) of EASA AD 2021-0171 specifies “if any discrepancy is detected, as defined in the applicable inspection ASB, before next flight, accomplish the applicable corrective action(s) in accordance with the instructions of Paragraph 3.B.1 of the applicable inspection ASB,” for this AD, a qualified mechanic must add oil to the TGB to the “max” level if the oil level is not at maximum. The instructions are for reference only and are not required for the actions in paragraph (5) of EASA AD 2021-0171.
(7) Where paragraph (6) of EASA AD 2021-0171 refers to “any discrepancy,” for this AD, discrepancies include the presence of particles and other conditions such as abrasions, scales, flakes, and splinters.
(8) Where the service information referred to in EASA AD 2021-0171 specifies to perform a metallurgical analysis and contact the manufacturer if collected particles are not clearly characterized, this AD does not require contacting the manufacturer to determine the characterization of the particles collected.
(9) Although service information referenced in EASA AD 2021-0171 specifies to scrap parts, this AD does not include that requirement.
(10) Although service information referenced in EASA AD 2021-0171 specifies reporting information to Airbus Helicopters, filling in a “particle detection” follow-up sheet, and returning a “bearing monitoring sheet” to Airbus Helicopters, this AD does not include those requirements.
(11) Although service information referenced in EASA AD 2021-0171 specifies returning certain parts to an approved workshop and returning certain parts to Airbus Helicopters, this AD does not include those requirements.
Although the service information referenced in EASA AD 2021-0171 specifies to submit certain information to the manufacturer, this AD does not include that requirement.
