AD 2020-21-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Airbus | Helicopters Model AS-365N2 | Airworthiness Directives; Airbus Helicopters |
Unsafe Condition
Loss of tightening torque of the Shur-Lok nut, which serves as a retainer of the tail rotor (T/R) drive flange of the main gearbox, possibly resulting in disengagement of the T/R drive flange, reduction of T/R drive control, rear transmission vibrations, and subsequent loss of control of the helicopter.
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Required Actions
Modifying the main gearbox (MGB) tail rotor (T/R) drive flange installation by removing the sliding flange from the flexible coupling and installing the sliding flange with aft output stop part number 365A32-7836-20 added, as per helicopter model and configuration, and installing modification 0763C81, which consists of installing a rear output stop with 5 spigots on the T/R shaft flexible coupling.
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Compliance Time
Within 600 hours time-in-service
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Affected Aircraft
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.
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Source: Official FAA Source ↗
Retrieved: Apr 4, 2026
Rights: U.S. Government Public Domain
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