Airworthiness Directive 99-04-15
one-timeAirworthiness Directives; Dr.Ing.h.c.F. Porsche Aktiengesellschaft (Porsche) 3200N01, N02, and N03 Reciprocating Engines
What this AD requires
This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 99-04-15 that was sent previously to all known U.S. owners and operators of Porsche PFM3200N01, N02, and N03 reciprocating engines by individual letters. This AD requires replacement of valve springs prior to further flight on PFM3200N01, N02, and NO3 engines. This amendment is prompted by reports of six cases of undetected fatigue failures of valve springs, with one valve spring failure causing an in-flight engine failure that ended in an emergency landing. The actions specified by this AD are intended to prevent an in-flight engine shutdown due to undetected fatigue failures of valve springs.
Which aircraft AD 99-04-15 applies to
Installed on but not limited to Mooney M20L series airplanes; applies to each identified engine regardless of modification, alteration, or repair status.
Whether AD 99-04-15 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:
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.