Is AD 2018-20-21 a recurring Airworthiness Directive?

No — AD 2018-20-21 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 2018-20-21 apply to?

AD 2018-20-21 applies to Bombardier, Inc. — models CL-600-2B16, CL-600. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 2018-20-21

one-time

Official AD 2018-20-21 · FR doc 2018-22275 · 2018-10-16 · airframe

Airworthiness Directives; Bombardier, Inc., Airplanes

What this AD requires

We are adopting a new airworthiness directive (AD) for certain Bombardier, Inc., Model CL-600-2B16 (CL-604 Variants) airplanes. This AD was prompted by reports of floodlight lamps found burned and the corresponding circuit breaker tripped as a result of fluid entering the cockpit floodlight fixtures. This AD requires installation of new gasket seals on floodlight fixtures. We are issuing this AD to address the unsafe condition on these products.

Which aircraft AD 2018-20-21 applies to

MakesBombardier, Inc.

ModelsCL-600-2B16, CL-600

Serial-conditional — narrows to serials 5301–5665, 5701–5988, 6050–6070.

CL-604 Variants.

Whether AD 2018-20-21 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 2018-20-21 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.