Is AD 98-18-21 a recurring Airworthiness Directive?

Yes — AD 98-18-21 requires a repetitive inspection. Next-due depends on the aircraft's time in service.

Airworthiness Directive 98-18-21

Q: Which aircraft does AD 98-18-21 apply to?

AD 98-18-21 applies to Rolls-Royce — models RB211 Trent 875, RB211 Trent 877, RB211 Trent 884, RB211 Trent 892, RB211 Trent 892B, RB211 Trent. Serial/part conditions may narrow it to specific aircraft.

recurring

Official AD 98-18-21 · FR doc 98-25006 · 1998-09-22 · turbine engine

Airworthiness Directives; Rolls-Royce, plc RB211 Trent 800 Series Turbofan Engines

What this AD requires

This amendment adopts a new airworthiness directive (AD) that is applicable to Rolls-Royce, plc RB211 Trent 800 series turbofan engines. This action requires initial and repetitive ultrasonic inspections of fan blade roots for cracks, and replacement, if necessary, with serviceable parts. This amendment is prompted by reports of multiple fan blade root cracks in several factory test engines. The actions specified in this AD are intended to prevent fan blade failure, which could result in multiple fan blade release, uncontained engine failure, and possible damage to the aircraft.

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

Which aircraft AD 98-18-21 applies to

MakesRolls-Royce

ModelsRB211 Trent 875, RB211 Trent 877, RB211 Trent 884, RB211 Trent 892, RB211 Trent 892B, RB211 Trent

Part-conditional — FK23750, FK25975, FK25548, FK26757.

Applies to engines with fan blades P/N FK23750, FK25975, FK25548, or FK26757 installed.

Whether AD 98-18-21 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 98-18-21 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.