A-87-073
NTSB Safety Recommendation — Aviation
Recommendation text
THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: ISSUE AN AIRWORTHINESS DIRECTIVE APPLICABLE TO CESSNA MODELS C-172M, C-172N, AND C-172P; TO CESSNA MODEL 177 (1968 MODEL YEAR ONLY); TO PIPER MODEL PA-28-161; AND TO ROBINSON R-22-HP HELICOPTERS, REQUIRING COMPLIANCE WITH AVCO LYCOMING SERVICE BULLETIN 388A, "PROCEDURE TO DETERMINE EXHAUST VALVE CONDITION." EXHAUST VALVE GUIDE CLEARANCES IN THE AIRPLANE ENGINES SHOULD BE CHECKED WITHIN THE NEXT 25 HOURS OF OPERATION AND AT SUBSEQUENT ENGINE INTERVALS OF 300 HOURS, OR TRIENNIALLY, WHICHEVER OCCURS FIRST. SIMILAR CLEARANCES IN THE HELICOPTERS SHOULD BE CHECKED WITHIN THE NEXT 10 HOURS OF OPERATION AND AT SUBSEQUENT ENGINE INTERVALS OF 150 HOURS, OR BIENNIALLY, WHICHEVER OCCURS FIRST. IF THE VALVE GUIDE CLEARANCES ARE FOUND TO BE INADEQUATE, EXHAUST VALVE AND VALVE GUIDE PAIRS SHOULD BE REPLACED AS NECESSARY, OR THE VALVE GUIDES SHOULD BE CLEANED(REAMED) IN ACCORDANCE WITH AVCO LYCOMING SERVICE INSTRUCTION NO. 1425, PART III, "CLEANING PROCEDURE."
In plain language (FlightFinder summary)
The Federal Aviation Administration is asked to issue an airworthiness directive for certain Cessna, Piper, and Robinson aircraft models, mandating compliance with Avco Lycoming Service Bulletin 388A to check exhaust valve guide clearances. For airplanes, checks must occur within the next 25 hours and then every 300 hours or triennially; for helicopters, within the next 10 hours and then every 150 hours or biennially. If clearances are insufficient, exhaust valve and guide pairs must be replaced or the guides cleaned per Avco Lycoming Service Instruction No. 1425.
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).