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Airworthiness Directive 04-25791

recurring
AD 04-25791 · 2004-11-26 · turboshaft engine

Airworthiness Directives; Rolls-Royce Corporation (Formerly Allison Engine Company, Allison Gas Turbine Division, and Detroit Diesel Allison) (RRC) Models 250-C30R/3, -C30R/3M, -C47B, and -C47M Turboshaft Engines

What this AD requires

The FAA is superseding an existing airworthiness directive (AD) for RRC models 250-C30R/3, -C30R/3M, -C47B, and -C47M turboshaft engines. That AD currently requires initial and repetitive electrical signal inspections of the hydromechanical unit (HMU) Power Lever Angle (PLA) potentiometer. This ad continues to require those inspections and adds replacement of the existing HMU with a new design HMU as a mandatory terminating action to the repetitive inspection requirements. This AD results from the manufacturer releasing a redesigned HMU that has a dual-element potentiometer. We are issuing this AD to prevent uncommanded and sudden changes in engine power.

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 04-25791 applies to

MakesRolls-Royce Corporation
Models250-C30R/3, 250-C30R/3M, 250-C47B, 250-C47M, 250-C

Applies only to engines with a hydromechanical unit (HMU) whose part number is listed in Group A (1.A.) of RRC Alert Commercial Engine Bulletins CEB A-73-3103, Revision 4 (Dec 2, 2003), and CEB A-73-6030, Revision 4 (Dec 2, 2003), installed.

Whether AD 04-25791 actually applies to your aircraft (by serial and installed parts) and whether it’s already complied with comes from that aircraft’s records.

Supersession

Supersedes AD 2003-13-10.

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 04-25791 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.