Is AD 2015-17-21 a recurring Airworthiness Directive?

No — AD 2015-17-21 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 2015-17-21 apply to?

AD 2015-17-21 applies to Rolls-Royce — models 37, B-37, C-37, RB211-535E4. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 2015-17-21

one-time

Official AD 2015-17-21 · FR doc 2015-21729 · 2015-10-28 · turbine engine

Airworthiness Directives; Rolls-Royce plc Turbofan Engines

What this AD requires

We are adopting a new airworthiness directive (AD) for all Rolls-Royce plc (RR) RB211-535E4-37, RB211-535E4-B-37, and RB211-535E4- C-37 turbofan engines. This AD requires reducing the cyclic life limits for certain high-pressure turbine (HPT) disks, removing those disks that have exceeded the new life limit, and replacing them with serviceable parts. This AD was prompted by RR updating the life limits for certain HPT disks. We are issuing this AD to prevent failure of the HPT disk, which could result in uncontained disk release, damage to the engine, and damage to the airplane.

Which aircraft AD 2015-17-21 applies to

MakesRolls-Royce

Models37, B-37, C-37, RB211-535E4

Whether AD 2015-17-21 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 2015-17-21 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.