A-87-075
NTSB Safety Recommendation — Aviation
Recommendation text
THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: ISSUE AN AIRWORTHINESS DIRECTIVE APPLICABLE TO PIPER MODELS PA-18-150, PA-22-150, PA-25-150, AND PA-28-140 AIR PLANES; BEECH MUSKETEER A-23-19 SPORT AIRPLANES; MOONEY MARK 20 AIRPLANES; AND CHAMPION MODEL 7-GCB AIRPLANES WITH ENGINES USING SOLID STEM EXHAUST VALVES, REQUIRING: (A) INSPECTION OF THE ENGINE EXHAUST VALVE STEMS FOR EROSION OR "NECKING" WITHIN THE NEXT 50 HOURS OF OPERATION AND AT SUBSEQUENT INTERVALS OF 150 FLIGHT HOURS (IF ANY EVIDENCE OF EROSION IS FOUND IN THE AREA OF THE VALVE BETWEEN THE GUIDE AND THE SEAT, THE VALVES AND GUIDES SHOULD BE REPLACED); (B) 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-HOURS OR ANNUAL INSPECTIONS, WHICHEVER OCCURS FIRST (THE EXHAUST VALVES SHOULD BE INSPECTED FOR EVIDENCE OF EROSION, CRACKING, AND OTHER DEFECTS AND REPLACED AS NECESSARY); AND (C) INSTALLATION OF AVCO LYCOMING PART NO. 74541 HIGH COMPRESSION TYPE SODIUM COOLED EXHAUST VALVES IN THE ENGINES OF THESE AIRPLANES AT THE NEXT OVERHAUL.
In plain language (FlightFinder summary)
The Federal Aviation Administration is asked to issue an airworthiness directive covering specific Piper, Beech, Mooney, and Champion aircraft models with engines that have solid stem exhaust valves. The directive would require inspecting the exhaust valve stems for erosion or necking within the next 50 flight hours and every 150 hours thereafter, with replacement of valves and guides if erosion is found; complying with Avco Lycoming Service Bulletin No. 404 for exhaust valve inspection within 50 hours and then at each 100-hour or annual inspection; and installing Avco Lycoming Part No. 74541 sodium cooled exhaust valves at the next engine overhaul.
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).