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Airworthiness Directive 98-28966

recurring
AD 98-28966 · 1998-11-02 · airframe

Airworthiness Directives; Slingsby Aviation Limited Models Dart T.51, Dart T.51/17, and Dart T.51/17R Sailplanes

What this AD requires

This amendment adopts a new airworthiness directive (AD) that applies to all Slingsby Aviation Limited (Slingsby) Models Dart T.51, Dart T.51/17, and Dart T.51/17R sailplanes that are equipped with aluminum alloy spar booms. This AD requires repetitively inspecting the aluminum alloy spar booms and the wing attach fittings for delamination or corrosion damage, and repairing any delamination or corrosion damage found. This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for the United Kingdom. The actions specified by this AD are intended to prevent failure of the spar assembly and adjoining structure caused by delamination or corrosion damage to the aluminum alloy spar booms or the wing attach fittings, which could result in reduced controllability or loss of control of the sailplane.

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 98-28966 applies to

MakesSlingsby
ModelsDart T.51, Dart T.51/17, Dart T.51/17R

All serial numbers, but only sailplanes equipped with aluminum alloy spar booms (Slingsby TI No. 109/T51, Issue 2, provides guidance to determine whether so equipped).

Whether AD 98-28966 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 98-28966 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.