A-87-074
NTSB Safety Recommendation — Aviation
Recommendation text
THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: ISSUE AN AIRWORTHINESS DIRECTIVE APPLICABLE TO PIPER MODELS PA-28-140 AND PA-28-151; TO CESSNA MODELS C-172I, C-172K, C-172L, AND C-172M; AND TO GULFSTREAM AMERICAN MODELS AA5A, WHICH UTILIZE AVCO LYCOMING PART NO. 75068 ENGINE EXHAUST VALVES, REQUIRING: (A) COMPLIANCE WITH AVCO LYCOMING SERVICE BULLETIN NO. 404, "EXHAUST VALVE INSPECTION (HIGH LEAD FUEL OPERATION)" WITHIN THE NEXT 50 HOURS OF OPERATION AND AT SUBSEQUENT 100-HOUR OR ANNUAL INSPECTIONS, WHICHEVER OCCURS FIRST (THE EXHAUST VALVES IN THE ENGINES OF THESE AIRPLANES SHOULD BE INSPECTED FOR EVIDENCE OF EROSION, CRACKING, AND OTHER DEFECTS AND REPLACED AS NECESSARY); AND (B) INSTALLATION OF AVCO LYCOMING PART NO. 74541 HIGH COMPRESSION TYPE SODIUM COOLED EXHAUST VALVES IN THE ENGINES OF THESE AIRPLANES AT THE NEXT ENGINE OVERHAUL.
In plain language (FlightFinder summary)
The NTSB urged the FAA to mandate inspections for specific aircraft models using certain engine exhaust valves that may suffer damage from high-lead fuel. This directive requires checking these parts for wear and cracks within 50 hours of use and during regular maintenance intervals. Additionally, it calls for replacing the original valves with improved sodium-cooled versions when the engines undergo their next overhaul to enhance safety.
This plain-language summary is written by FlightFinder to explain the recommendation above. It is not the official wording — the verbatim NTSB text is quoted above.
Details
| Status | Closed - Unacceptable Action |
|---|---|
| Mode | Aviation |
| Closed | Jan 28, 1994 |
| NTSB number | DEN86LA161 |
| Addressees | FAA |
External links
NTSB safety recommendations are advisory; addressees are not legally required to adopt them. Source: NTSB CAROL (public domain).