Is AD 2018-18021 a recurring Airworthiness Directive?

No — AD 2018-18021 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 2018-18021 apply to?

AD 2018-18021 applies to Rolls-Royce Plc — models Viper Mk. 521, Viper Mk. 522, Viper Mk. 601-22, Viper. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 2018-18021

one-time

AD 2018-18021 · 2018-08-21 · turbine engine

Airworthiness Directives; Rolls-Royce plc Turbojet Engines

What this AD requires

We are superseding Airworthiness Directive (AD) 2016-03-03 for all Rolls-Royce plc (RR) Viper Mk. 521, Viper Mk. 522, and Viper Mk. 601-22 turbojet engines. AD 2016-03-03 required reducing the life of certain critical parts. This AD requires reducing the life of certain critical parts and adds additional engine parts to the applicability. This AD was prompted by a determination made by RR that additional parts for the applicable RR Viper turbojet engine models are affected. We are issuing this AD to address the unsafe condition on these products.

Which aircraft AD 2018-18021 applies to

MakesRolls-Royce Plc

ModelsViper Mk. 521, Viper Mk. 522, Viper Mk. 601-22, Viper

Whether AD 2018-18021 actually applies to your aircraft (by serial and installed parts) and whether it’s already complied with comes from that aircraft’s records.

Supersession

Supersedes AD 2016-03-03.

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 2018-18021 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.