Is AD 2021-21-23 a recurring Airworthiness Directive?

Yes — AD 2021-21-23 requires a repetitive inspection every 600 hours. Next-due depends on the aircraft's time in service.

Which aircraft does AD 2021-21-23 apply to?

AD 2021-21-23 applies to Bombardier — models CL-600-2B16, CL-600. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 2021-21-23

recurring

Official AD 2021-21-23 · FR doc 2022-00993 · 2022-01-21 · airframe

Airworthiness Directives; Bombardier, Inc., Airplanes

What this AD requires

The FAA is superseding Airworthiness Directive (AD) 2017-22- 06, which applied to certain Bombardier, Inc., Model CL-600-2B16 (601- 3A, 601-3R, and 604 Variants) airplanes. AD 2017-22-06 required repetitive inspections for fuel leakage at the engine and auxiliary power unit (APU) fuel pumps, and related investigative and corrective actions if necessary. This AD retains the requirements of AD 2017-22- 06, and requires an inspection of the APU, repair if necessary, and modification of the engine electrical fuel pump (EFP) installation. This AD also adds airplanes to the applicability. This AD was prompted by reports of fuel leaks from the electrical connectors and conduits of the engine and APU EFP cartridge/canister, and the development of additional actions to address the root cause of the fuel leaks. The FAA is issuing this AD to address the unsafe condition on these products.

Repetitive inspection. Re-inspect every 600 hours. The next-due date/hours depend on this aircraft’s time in service — a records report computes it from the logbooks.

Which aircraft AD 2021-21-23 applies to

MakesBombardier

ModelsCL-600-2B16, CL-600

Serial-conditional — narrows to serials 5301–5665, 5701–5990, 6050–6163.

Includes 601-3A, 601-3R, and 604 variants.

Whether AD 2021-21-23 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 2021-21-23 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.