Buckeye, AZ, USA
N5SX
Fonville SWEARINGEN SX300
The pilot departed uneventfully, leveled the airplane at 1,000 ft above ground level, and set the engine power to 2,500 rpm. He then initiated a climb, during which the engine power increased to 3,200 rpm and the engine became “unresponsive to input” just before it lost power. The pilot initiated a forced landing, during which the pilot sustained minor injuries and the airplane sustained substantial damage. A postaccident examination of the engine revealed the left magneto flange was securely clamped at the mounting pad; however, the flange was detached from the magneto. The three screw holes where the flange and magneto should have attached exhibited severe elongation and deformation, which was indicative of a loss of torque and subsequent prolonged inability to maintain proper mating of the magneto flange and housing. The three attachment screws were not recovered. The condition observed during postaccident examination likely existed for an extended time as evidenced by fretting and wear signatures of the housing components. Internally, the magneto components become misaligned to such a degree that proper magneto internal timing and the ability to operate within the manufacturer’s specification were affected, resulting in the total loss of engine power.
On September 18, 2021, about 0824 mountain daylight time, a Swearingen SX300 airplane, N5SX, was substantially damaged when it was involved in an accident near Buckeye, Arizona. The pilot sustained minor injuries and the passenger was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that his takeoff was uneventful, and he leveled the airplane at 1,000 ft above ground level (agl) and set the engine power to 2,500 rpm (the airspeed was 180 knots). He then initiated a climb, during which the engine power increased to 3,200 rpm and the engine became “unresponsive to input” just before it lost power. The pilot initiated a forced landing, during which the airplane sustained substantial damage to the wings and fuselage. A postaccident examination of the engine revealed the left magneto flange was securely clamped at the mounting pad; however, the flange was detached from the magneto. The magneto was removed for further examination. The three attachment screws were not recovered. The screw holes exhibited severe elongation and deformation which affected the mating of the magneto flange and housing. Examination of the oil filter element found copious amounts of non-ferrous (non-magnetic) metal contamination. The pilot reported that he departed with 66 gallons of fuel. The airplane had a Garmin GTN-750 GPS installed. The data from the GPS was downloaded after the accident and a graphical overlay was generated using Google Earth for the accident flight. An image was created highlighting an area of the tracklog where the airplane climbed rapidly to a higher altitude and then began a steady descent profile. Just prior to 0823, the airplane was traveling along terrain at a recorded altitude between 1,300 and 1,500 ft mean sea level (msl) and a groundspeed of about 220 knots. Around 0823, the airplane rapidly climbed and reached an altitude of just under 2,500 ft msl by 0823:12. The airplane began a descent; the GPS tracklog showed it maneuvered near terrain an ultimately toward a small road while descending. The tracklog ended in the vicinity of a road. The derived groundspeed at the time of the last data point was about 98 knots and the recorded altitude was 1,143 ft msl. The airplane also had a JP Instruments (JPI) engine data monitor installed. The device was downloaded after the accident and indicated 3.6 gallons of fuel were used during the flight.
The total loss of engine power due to the failure of the left magneto.
Source: NTSB Aviation Accident Database
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