Narrative:

This event involves an engine overspd condition. Upon notification of the event, a repair station work order was generated. The tcm (teledyne continental manual) engine overspd instructions were followed as provided by tcm M89-15 service bulletin, which involved partial disassembly of the engine valve train and inspections of various components and to repeat the inspection after 5 flight hours if no problems were found. I also consulted the hartzell propeller manual #115N, under the special inspections overspd/over-torque chapter of the inspection and check section of the manual. In this section there are 3 graphs. Figure 503, reciprocating engine overspd limits. Figure 504, turbine engine overspd limits and figure 505, turbine engine over-torque limits. At this point, I'm not sure if I looked at the wrong graph or if I punched the wrong information into the calculator when attempting to define the percent of overspd. But either way, the determination was made that the overspd condition that occurred did not require any maintenance action. I had confusion perhaps with the charts in the manual. There are 2 for turbine applications in the propeller manual for a reciprocating engine application. I was looking over some information for another aircraft when I came across a reference to propeller overspd. The number that I noticed didn't strike me as to what I remembered was the case with this situation. I pulled the work order for review and immediately realized the mistake. The aircraft was grounded. Supplemental information from acn 576771: it was found that the propeller did meet the criteria that requires an inspection. The problem was discovered during a work order review by the chief inspector. Supplemental information from acn 576768: engine overspd situation was evaluated by the chief inspector incorrectly. Information was evaluated by only 1 person.

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Original NASA ASRS Text

Title: A CIRRUS SR22 WAS RELEASED FOR SVC WITH NO ACTION AFTER A RPTED PROP OVERSPD. LATER FOUND PROP OVERSPD INSPECTION REQUIRED.

Narrative: THIS EVENT INVOLVES AN ENG OVERSPD CONDITION. UPON NOTIFICATION OF THE EVENT, A REPAIR STATION WORK ORDER WAS GENERATED. THE TCM (TELEDYNE CONTINENTAL MANUAL) ENG OVERSPD INSTRUCTIONS WERE FOLLOWED AS PROVIDED BY TCM M89-15 SVC BULLETIN, WHICH INVOLVED PARTIAL DISASSEMBLY OF THE ENG VALVE TRAIN AND INSPECTIONS OF VARIOUS COMPONENTS AND TO REPEAT THE INSPECTION AFTER 5 FLT HRS IF NO PROBS WERE FOUND. I ALSO CONSULTED THE HARTZELL PROP MANUAL #115N, UNDER THE SPECIAL INSPECTIONS OVERSPD/OVER-TORQUE CHAPTER OF THE INSPECTION AND CHK SECTION OF THE MANUAL. IN THIS SECTION THERE ARE 3 GRAPHS. FIGURE 503, RECIPROCATING ENG OVERSPD LIMITS. FIGURE 504, TURBINE ENG OVERSPD LIMITS AND FIGURE 505, TURBINE ENG OVER-TORQUE LIMITS. AT THIS POINT, I'M NOT SURE IF I LOOKED AT THE WRONG GRAPH OR IF I PUNCHED THE WRONG INFO INTO THE CALCULATOR WHEN ATTEMPTING TO DEFINE THE PERCENT OF OVERSPD. BUT EITHER WAY, THE DETERMINATION WAS MADE THAT THE OVERSPD CONDITION THAT OCCURRED DID NOT REQUIRE ANY MAINT ACTION. I HAD CONFUSION PERHAPS WITH THE CHARTS IN THE MANUAL. THERE ARE 2 FOR TURBINE APPLICATIONS IN THE PROP MANUAL FOR A RECIPROCATING ENG APPLICATION. I WAS LOOKING OVER SOME INFO FOR ANOTHER ACFT WHEN I CAME ACROSS A REF TO PROP OVERSPD. THE NUMBER THAT I NOTICED DIDN'T STRIKE ME AS TO WHAT I REMEMBERED WAS THE CASE WITH THIS SIT. I PULLED THE WORK ORDER FOR REVIEW AND IMMEDIATELY REALIZED THE MISTAKE. THE ACFT WAS GNDED. SUPPLEMENTAL INFO FROM ACN 576771: IT WAS FOUND THAT THE PROP DID MEET THE CRITERIA THAT REQUIRES AN INSPECTION. THE PROB WAS DISCOVERED DURING A WORK ORDER REVIEW BY THE CHIEF INSPECTOR. SUPPLEMENTAL INFO FROM ACN 576768: ENG OVERSPD SIT WAS EVALUATED BY THE CHIEF INSPECTOR INCORRECTLY. INFO WAS EVALUATED BY ONLY 1 PERSON.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.