What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
(-23) On 04/15/99 Piper navajo, N57AS, departed bracket airport on a test flight following a right engine manifold pressure adjustment. Prior to departure the right engine upper cowling was removed and the pressure differential controller was adjusted by a certificated mechanic. The certificated mechanic went home and left the cowling installation to be completed by an unsupervised, uncertificated mechanic. The unsupervised mechanic installed the cowling and failed to secure the inboard latches. The aircraft cowling departed the aircraft after level flight was accomplished. The cowling wrapped around the right horizontal stabilizer. The pilot declared a mayday due to conrol problems with the aircraft. The aircraft was brought under control and landed at brackett without further incident. (.4) the aircraft had been in maintenance for an adjustment to the right engine manifold pressure differential controller. The procedure required the uncowling of the engine. A certificated airframe and powerplant mechanic removed the cowling and made the required adjustments, then left for the day. A noncertificated mechanic replaced the cowling and the pilot then proceeded to perform the postma intenance test flight. During climbout, the right engine upper cowling separated and wrapped around the right horizontal stabilizer. The pilot experienced difficulty in controlling the aircraft until the airspeed was reduced, then he returned to the airport and landed. Inspection of the cowling disclosed that the inboard latches on the upper cowling were not damaged. In his written statement, the pilot notes that his failure to detect the unlatched inboard cowling fasteners resulted from 'poor preflight inspection habits and a failure to follow the checklist.'
As the FAA filed it
(-23) ON 04/15/99 PIPER NAVAJO, N57AS, DEPARTED BRACKET AIRPORT ON A TEST FLIGHT FOLLOWING A RIGHT ENGINE MANIFOLD PRESSURE ADJUSTMENT. PRIOR TO DEPARTURE THE RIGHT ENGINE UPPER COWLING WAS REMOVED AND THE PRESSURE DIFFERENTIAL CONTROLLER WAS ADJUSTED BY A CERTIFICATED MECHANIC. THE CERTIFICATED MECHANIC WENT HOME AND LEFT THE COWLING INSTALLATION TO BE COMPLETED BY AN UNSUPERVISED, UNCERTIFICATED MECHANIC. THE UNSUPERVISED MECHANIC INSTALLED THE COWLING AND FAILED TO SECURE THE INBOARD LATCHES. THE AIRCRAFT COWLING DEPARTED THE AIRCRAFT AFTER LEVEL FLIGHT WAS ACCOMPLISHED. THE COWLING WRAPPED AROUND THE RIGHT HORIZONTAL STABILIZER. THE PILOT DECLARED A MAYDAY DUE TO CONROL PROBLEMS WITH THE AIRCRAFT. THE AIRCRAFT WAS BROUGHT UNDER CONTROL AND LANDED AT BRACKETT WITHOUT FURTHER INCIDENT. (.4) THE AIRCRAFT HAD BEEN IN MAINTENANCE FOR AN ADJUSTMENT TO THE RIGHT ENGINE MANIFOLD PRESSURE DIFFERENTIAL CONTROLLER. THE PROCEDURE REQUIRED THE UNCOWLING OF THE ENGINE. A CERTIFICATED AIRFRAME AND POWERPLANT MECHANIC REMOVED THE COWLING AND MADE THE REQUIRED ADJUSTMENTS, THEN LEFT FOR THE DAY. A NONCERTIFICATED MECHANIC REPLACED THE COWLING AND THE PILOT THEN PROCEEDED TO PERFORM THE POSTMA INTENANCE TEST FLIGHT. DURING CLIMBOUT, THE RIGHT ENGINE UPPER COWLING SEPARATED AND WRAPPED AROUND THE RIGHT HORIZONTAL STABILIZER. THE PILOT EXPERIENCED DIFFICULTY IN CONTROLLING THE AIRCRAFT UNTIL THE AIRSPEED WAS REDUCED, THEN HE RETURNED TO THE AIRPORT AND LANDED. INSPECTION OF THE COWLING DISCLOSED THAT THE INBOARD LATCHES ON THE UPPER COWLING WERE NOT DAMAGED. IN HIS WRITTEN STATEMENT, THE PILOT NOTES THAT HIS FAILURE TO DETECT THE UNLATCHED INBOARD COWLING FASTENERS RESULTED FROM 'POOR PREFLIGHT INSPECTION HABITS AND A FAILURE TO FOLLOW THE CHECKLIST.'
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.