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Airworthiness Directive 98-24-28

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Official AD 98-24-28 · FR doc 98-31702 · 1998-12-03 · turboshaft engine

Airworthiness Directives; Allison Engine Company 250-B and 250-C Series Turboshaft and Turboprop Engines

What this AD requires

This amendment adopts a new airworthiness directive (AD), applicable to certain Allison Engine Company 250-B and 250-C series turboshaft and turboprop engines, that requires replacing existing beryllium copper main fuel control (MFC) bellows assemblies with Inconel 718 stainless steel welded MFC bellows assemblies. This amendment is prompted by reports of leaking MFC bellows assemblies resulting in an uncommanded minimum fuel flow condition, loss of engine fuel flow control and subsequent forced landing. The actions specified by this AD are intended to prevent MFC bellows assembly leakage, which can result in an uncommanded minimum fuel flow condition and subsequent loss of engine fuel flow control.

Which aircraft AD 98-24-28 applies to

MakesAllison
Models250-B15, 250-B17, 250-B17F, 250-C18, 250-C20, 250-C20R, 250-C28, 250-C30, 250

AD covers both 250-B series turboprop engines and 250-C series turboshaft engines, installed on numerous fixed-wing airplane, rotorcraft, and airship models.

Whether AD 98-24-28 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 98-24-28 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.