What was found
AIRCRAFT OPERATOR REPORTED ROUGH RUNNING ENGINE. OWNER REMOVED TOP COWL AND FOUND NR 3 FUEL INJECTION LINE COMPLETELY BROKEN OFF AT AND JUST BEHIND WHERE NUT AND FITTING ARE WELDED TO LINE. FURTHER INSPECTION REVEALED NR 4 CYLINDER OIL RETURN TUBE CHAFED THROUGH BY FUEL INJECTION LINE AT THIS AREA (VIBRATING). OIL RETURN LINE AND FUEL INJECTION LINE BOTH REPLACED WITH NEW PARTS. FUEL INJECTION T-FITTING ON 2ND, 4TH, AND 6TH BANK OF CYLINDERS WAS FOUND LOOSE AT THIS TIME AND RESECURED.