Is AD 2020-21-01 a recurring Airworthiness Directive?

No — AD 2020-21-01 is a one-time directive. Verify it was complied with in the aircraft's records.

Airworthiness Directive 2020-21-01

Q: Which aircraft does AD 2020-21-01 apply to?

AD 2020-21-01 applies to Airbus Helicopters — models AS-365N2, AS-365N3, EC155B, EC155B1, SA-365N1, AS-365, EC155, SA-365. Serial/part conditions may narrow it to specific aircraft.

one-time

Official AD 2020-21-01 · FR doc 2020-22241 · 2020-10-08 · airframe

Airworthiness Directives; Airbus Helicopters

What this AD requires

The FAA is adopting a new airworthiness directive (AD) for certain Airbus Helicopters Model AS-365N2, AS 365N3, EC 155B, EC155B1, and SA-365N1 helicopters. This AD requires 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 T/R drive flange. The actions of this AD are intended to address an unsafe condition on these products.

Which aircraft AD 2020-21-01 applies to

MakesAirbus Helicopters

ModelsAS-365N2, AS-365N3, EC155B, EC155B1, SA-365N1, AS-365, EC155, SA-365

Applies only to helicopters with modification 0763B64 installed, except those with modification 0763C81.

Whether AD 2020-21-01 actually applies to your aircraft (by serial and installed parts) and whether it’s already complied with comes from that aircraft’s records.

How AD compliance is recorded

A valid compliance record (14 CFR 43.9) states:

Method of compliance — The specific action taken (inspected, replaced, modified) and to what revision.

Date — When the work was done.

Aircraft time — Total time in service / tach at compliance — how recurring next-due is computed.

Signature & certificate — The A&P/IA who returned it to service, with certificate number.

Is AD 2020-21-01 complied with on your aircraft?

Tailplate reads a tail number’s logbooks and matches every applicable AD — including this one — to its compliance evidence, with recurring next-due dates computed.

Look up a tail number →Read the full directive (Federal Register)

Applicability is derived from the FAA directive corpus and is advisory, not a legal airworthiness determination. Compliance is established only from an aircraft’s actual records.