A-86-124
NTSB Safety Recommendation — Aviation
Recommendation text
THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: ISSUE AN AIRWORTHINESS DIRECTIVE REQUIRING: (1) COMPLIANCE WITH TELEDYNE CONTINENTAL MOTORS (TCM) SERVICE BULLETIN M 81-2 REV. 1, "CRANKSHAFT ULTRASONIC INSPECTION," EACH TIME AIRMELT STEEL ALLOY CRANKSHAFTS FROM TCM IO-520 AND TSIO-520 SERIES ENGINES ARE REMOVED FOR OVERHAUL OR FOR ANY REASON; (2) THAT ALL TCM IO-520 OR TSIO-520 SERIES ENGINE AIRMELT STEEL ALLOY CRANKSHAFTS WHICH HAVE NOT BEEN PREVIOUSLY INSPECTED ULTRASONICALLY AND WHICH HAVE LESS THAN 1,200 HOURS TOTAL TIME IN SERVICE SINCE MANUFACTURED BE REMOVED AND INSPECTED IN ACCORDANCE WITH TCM SERVICE BULLETIN M 81-2 REV. 1 WITHIN THE NEXT 50 HOURS, AND (3) THAT THE HEAT CODES AND TYPE OF STEEL USED ON CRANKSHAFTS INSTALLED IN TCM IO-520 AND TSIO-520 ENGINES BE RECORDED IN THE ENGINE MAINTENANCE LOG ANY TIME THE ENGINE IS DISASSEMBLED FOR OVERHAUL OR FOR ANY REASON. CRANKSHAFTS IDENTIFIED AS BEING SUSCEPTIBLE TO FATIGUE (HAVING "SUSPECT" HEAT CODES) SHOULD BE REPLACED WITH THE IMPROVED/REDESIGNED CRANKSHAFTS INTRODUCED IN 1978 OR THE ENGINE SHOULD BE EXCHANGED FOR A REDESIGNED "B" ENGINE, I.E., THOSE MANUFACTURED FROM VACUUM ARC REMELT STEEL WHICH INCORPORATE THE REDESIGNED CRANKSHAFT.
In plain language (FlightFinder summary)
The FAA is asked to issue an airworthiness directive requiring compliance with Teledyne Continental Motors Service Bulletin M 81-2 Rev. 1 for ultrasonic inspection of certain crankshafts each time an engine is overhauled or removed. They must also mandate the removal and inspection within 50 hours of any previously uninspected crankshafts with less than 1,200 total hours, and require recording heat codes and steel type in engine maintenance logs. Crankshafts with suspect heat codes should be replaced with improved designs or the engine exchanged for a redesigned model.
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 - Acceptable Alternate Action |
|---|---|
| Mode | Aviation |
| Closed | May 6, 1988 |
| NTSB number | CHI82FA110 |
| Addressees | FAA |
External links
NTSB safety recommendations are advisory; addressees are not legally required to adopt them. Source: NTSB CAROL (public domain).