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Airworthiness Directive 99-14-06

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Official AD 99-14-06 · FR doc 99-16745 · 1999-07-08 · propeller

Airworthiness Directives; MT-Propeller Entwicklung GMBH Models MTV-9-B-C and MTV-3-B-C Propellers

What this AD requires

This amendment adopts a new airworthiness directive (AD) that is applicable to MT-Propeller Entwicklung GMBH Models MTV-9-B-C and MTV-3-B-C propellers. This action requires initial and repetitive inspections of Torx head blade root lag screws for torque values and breakage, and, if any screws are found broken or with insufficient torque, replacement of all screws with new lag screws. In addition, this AD requires replacement of certain model Torx head blade root lag screws with improved, hexagonal head blade root lag screws. This amendment is prompted by reports of broken Torx head blade root lag screws. The actions specified in this AD are intended to prevent blade root lag screw breakage, which could result in propeller blade separation and loss of control of the airplane.

Repetitive inspection. Re-inspect every 100 hours or 12 months. The next-due date/hours depend on this aircraft’s time in service — a records report computes it from the logbooks.

Which aircraft AD 99-14-06 applies to

MakesMt-Propeller Entwicklung Gmbh
ModelsMTV-9-B-C, MTV-3-B-C, MTV-9, MTV-3
Part-conditional — A-549-85, A-550-85.

Applies to propellers with hub serial numbers starting with 98 or less. MTV-9-B-C propellers require CL250-27 or CL260-27 blades (S/N prefix letter A through P); MTV-3-B-C propellers require L250-21 blades (S/N prefix letter A through P). Both require Torx head blade root lag screws, P/N A-549-85 (3mm thread pitch) or P/N A-550-85 (4mm thread pitch).

Whether AD 99-14-06 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 99-14-06 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.