As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON RETURN TO BASE, PILOT REPORTED WHEN CLIMING TO 8000 PT ENGINE SURGED/POWER DROP 2 TIMES. AIRCRAFT WAS DUE A PHASE 1 INSPECTION. WHILE INSPECTING THE ALT AIR DOOR, NOTICED THE DOOR STUCK IN THE OPEN POSITION. FURTHER INSPECTION REVEALED THE SPRING THAT CONTROLS THE DOOR WAS MISSING FROM THE HINGE ASSY. INSPECTED INSIDE OF SERVO. NO DAMAGE BUT DID NOT LOCATE THE SPRING. THE DOOR SHOWS SIGNS OF WEAR ON SEALING EDGES. FEEL THE SYSTEM IS WEAK AND NEEDS TO BE IMPROVED. (K)