Narrative:

A recent incident occurred involving an engine that I overhauled in 2000. The aircraft involved is a fairchild PT23. The owner tried to start the engine after the aircraft had been in storage for 1 yr and hydraulic-locked the engine resulting in a bent link rod in #4 cylinder. The FAA was present at the tear-down where this damage was revealed. Also present was the owner and mechanic. Although we had requested to be there for the tear-down, we were not advised nor invited to attend. The FAA representative and mechanic noticed that the piston I installed did not match the piston shown in the original engine parts manual for cont W670-6A as the oil control ring on the original piston is in the second groove position, but the piston installed has the oil control ring in the 4TH groove. The FAA is suspect that I used the wrong pistons. However, the pistons that we installed are a modified part, approved under stc SE4127SW issued to xyz incorporated, and are approved for use in this engine. Stc SE4127SW covers the installation of modified W670-23 piston, part number 4180, to replace W670-6A piston, part number 4177. When I documented the engine overhaul in the engine log I did not include information regarding the stc pistons or furnish a form 337 (major repair or alternation form) as the parts were supplied to me as a finished part and included approval tags (yellow tags) from xyz incorporated, showing the stc number and return to service information. These parts approval tags and all other parts identify information, was saved in the aircraft records portfolio. The owners say they cannot find this information.

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Original NASA ASRS Text

Title: A TECHNICIAN RPTS FAA INSPECTOR ALLEGES WRONG PISTONS WERE INSTALLED DURING ENG OVERHAUL. PISTON MODIFIED AND APPROVED FOR ENG UNDER STC.

Narrative: A RECENT INCIDENT OCCURRED INVOLVING AN ENG THAT I OVERHAULED IN 2000. THE ACFT INVOLVED IS A FAIRCHILD PT23. THE OWNER TRIED TO START THE ENG AFTER THE ACFT HAD BEEN IN STORAGE FOR 1 YR AND HYD-LOCKED THE ENG RESULTING IN A BENT LINK ROD IN #4 CYLINDER. THE FAA WAS PRESENT AT THE TEAR-DOWN WHERE THIS DAMAGE WAS REVEALED. ALSO PRESENT WAS THE OWNER AND MECH. ALTHOUGH WE HAD REQUESTED TO BE THERE FOR THE TEAR-DOWN, WE WERE NOT ADVISED NOR INVITED TO ATTEND. THE FAA REPRESENTATIVE AND MECH NOTICED THAT THE PISTON I INSTALLED DID NOT MATCH THE PISTON SHOWN IN THE ORIGINAL ENG PARTS MANUAL FOR CONT W670-6A AS THE OIL CTL RING ON THE ORIGINAL PISTON IS IN THE SECOND GROOVE POS, BUT THE PISTON INSTALLED HAS THE OIL CTL RING IN THE 4TH GROOVE. THE FAA IS SUSPECT THAT I USED THE WRONG PISTONS. HOWEVER, THE PISTONS THAT WE INSTALLED ARE A MODIFIED PART, APPROVED UNDER STC SE4127SW ISSUED TO XYZ INC, AND ARE APPROVED FOR USE IN THIS ENG. STC SE4127SW COVERS THE INSTALLATION OF MODIFIED W670-23 PISTON, PART NUMBER 4180, TO REPLACE W670-6A PISTON, PART NUMBER 4177. WHEN I DOCUMENTED THE ENG OVERHAUL IN THE ENG LOG I DID NOT INCLUDE INFO REGARDING THE STC PISTONS OR FURNISH A FORM 337 (MAJOR REPAIR OR ALTERNATION FORM) AS THE PARTS WERE SUPPLIED TO ME AS A FINISHED PART AND INCLUDED APPROVAL TAGS (YELLOW TAGS) FROM XYZ INC, SHOWING THE STC NUMBER AND RETURN TO SVC INFO. THESE PARTS APPROVAL TAGS AND ALL OTHER PARTS IDENT INFO, WAS SAVED IN THE ACFT RECORDS PORTFOLIO. THE OWNERS SAY THEY CANNOT FIND THIS INFO.

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.