What was found
(AUS) PILOT REPORTED UNUSUAL NOISE COMING FROM THE RT ENGINE AND SUSPECTED A STICKY VALVE. AFTER ENGINE RUNS, THE COWLS WERE REMOVED FROM THE RT ENGINE TO CARRY OUT A COMPRESSION CHECK. IT WAS THEN NOTICED THAT THE NR 3 EXHAUST STACK WAS NOT FITTED TO THE NR 3 CYLINDER. THE STACK WAS APPROX 3.81 CM (1.5 INCHES) BELOW ITS CORRECT POSITION. SUSPECT THAT EITHER THE EXHAUST STACK WAS NOT FITTED OR WAS FITTED INCORRECTLY.