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Airworthiness Directive 2001-24-51

recurring
Official AD 2001-24-51 · FR doc 02-8595 · 2002-04-12 · airframe

Airworthiness Directives; MD Helicopters, Inc. Model 600N Helicopters

What this AD requires

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 2001-24-51, which was sent previously to all known U.S. owners and operators of MD Helicopters, Inc. (MDHI) Model 600N helicopters by individual letters. This AD requires, within 5 hours time-in-service (TIS), inspecting both upper tailboom attachments, nutplates and both angles for a crack or thread damage and repairing or replacing any cracked or damaged part before further flight. Also, this AD requires replacing the upper right-hand (RH) tailboom attachment bolt (bolt) with a new bolt, and if the upper RH bolt is broken, replacing the three remaining bolts with airworthy bolts before further flight. Adding a washer to each bolt and modifying both upper access covers are also required. Thereafter, at specified intervals, inspecting the upper tailboom attachments and repairing or replacing any cracked part before further flight is required. This AD is prompted by the discovery of a cracked bolt on a helicopter. The actions specified by this AD are intended to prevent failure of a tailboom attachment, loss of the tailboom, and subsequent loss of control of the helicopter.

Repetitive inspection. Re-inspect every 25 hours. The next-due date/hours depend on this aircraft’s time in service — a records report computes it from the logbooks.

Which aircraft AD 2001-24-51 applies to

MakesMd Helicopters
Models600N
Part-conditional — 500N3422, 500N3422-3, 500N3429-6, 500N3429-7, AN960C516, NAS1149C0563R, AN960C616, NAS1149C0663R.

MD 600N upper tailboom attachment fittings, nutplates, angles, and bolts per MDHI Service Bulletin SB600N-036.

Whether AD 2001-24-51 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 2001-24-51 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.