Is AD 2011-21-17 a recurring Airworthiness Directive?

No — AD 2011-21-17 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 2011-21-17 apply to?

AD 2011-21-17 applies to General Electric Company — models CT7-8A, CT7-8A1, CT7-8E, CT7-8F5, CT7. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 2011-21-17

one-time

Official AD 2011-21-17 · FR doc 2011-28353 · 2011-11-02 · turboshaft engine

Airworthiness Directives; General Electric Company Turboshaft Engines

What this AD requires

We are adopting a new airworthiness directive (AD) for all General Electric Company (GE) CT7-8A, CT7-8A1, CT7-8E, and CT7-8F5 turboshaft engines with a fuel filter differential pressure switch, part number (P/N) TD028VF0H7Y5 (part of the fuel filter assembly, P/N 4110T53P06) installed. This AD requires daily visual inspections of the fuel filter differential pressure switch for fuel leaks and for excessive cracking of the switch mounting flanges due to stress- corrosion. This AD also requires the installation of a collar kit over the fuel filter differential pressure switch as terminating action to the daily inspections. This AD was prompted by reports of 47 fuel filter differential pressure switches found with stress-corrosion cracking of the mounting flanges. We are issuing this AD to prevent unrecoverable in-flight engine shutdown, engine bay fire due to fuel leakage, and forced landing or accident.

Which aircraft AD 2011-21-17 applies to

MakesGeneral Electric Company

ModelsCT7-8A, CT7-8A1, CT7-8E, CT7-8F5, CT7

Part-conditional — TD028VF0H7Y5, 4110T53P06.

Applies only when fuel filter differential pressure switch P/N TD028VF0H7Y5 (part of fuel filter assembly P/N 4110T53P06) is installed.

Whether AD 2011-21-17 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 2011-21-17 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.