ERA23LA285

The pilot intended to fly his airplane to an airport for an annual inspection. During the flight, while climbing to cruise altitude, the engine began to lose power. The pilot subsequently attempted a forced landing to a school field. During the forced landing, the airplane was in a steep right bank when the wingtip struck the ground, resulting in substantial damage to the empennage. The postaccident examination of the engine revealed that the diesel engine’s turbocharger induction housing was fractured in half and exhibited signs of an existing fracture surface. Further metallurgical examination revealed that the turbocharger housing separated consistent with fatigue cracking. The fatigue cracking emanated from the outer surface of the housing and proceeded circumferentially. Steps on the fracture surface indicated that fatigue cracking on multiple planes had coalesced into one main fatigue crack. The remainder of the fracture surface had macro features consistent with overstress. Based on this information, it is likely that failure of the turbocharger housing resulted in a reduced quantity of intake air being available to the engine and resulted in the partial loss of engine power described by the pilot.

On June 29, 2023, at 1222 eastern daylight time, a Diamond DA 40 NG, N44HH, was substantially damaged when it was involved in an accident near Yorktown Heights, New York. The pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, who was also the owner of the airplane, he intended to fly to Orange County Airport (MGJ), Montgomery, New York, for an annual inspection. He departed Westchester County Airport (HPN), White Plains, New York, and while climbing to cruise altitude, about 2,000 ft mean sea level (msl), the engine began to lose power. The indicated power displayed as lower than normal at 75% and the climb rate was diminishing. The pilot reported the power loss to the air traffic controller. The engine power then dropped to 68% and the airplane began to descend. The pilot looked for a field to conduct a forced landing and was “crabbing” towards West Point as the airplane descended to 1200 ft msl. He moved the throttle in an attempt to regain engine power; however, only the propeller pitch changed. The pilot subsequently attempted a forced landing to a school field. The airplane was in a steep right bank when the wingtip struck the ground. The airplane yawed right and impacted the ground with the left forward side of the nose and slid to a stop. During the accident sequence the airplane sustained substantial damage to the empennage. The airplane was equipped with a 168-hp Austro Engine E4 diesel engine. The engine was examined at a salvage facility; the engine’s turbocharger induction housing was fractured in half and exhibited signs of an existing fracture surface. The propeller blades were all fractured near the hub. The glow plugs were removed and the propeller was rotated by hand; air pressure was heard exiting the glow plug holes. The engine rotated smoothly and did not exhibit evidence of any preimpact mechanical anomalies. The turbocharger was sent to the National Transportation Safety Board Materials Laboratory for further examination. The examination revealed that the turbocharger housing separated consistent with fatigue cracking. The fatigue cracking emanated from the outer surface of the housing and proceeded circumferentially. Steps on the fracture surface indicated fatigue cracking on multiple planes had coalesced into one main fatigue crack. The remainder of the fracture surface had macro features consistent with overstress (for further information, see the Materials Laboratory Factual Report in the public docket for this investigation). According to the pilot, and the airplane’s maintenance records, at the time of the airplane’s most recent annual inspection in June 2022, the airframe and engine had accumulated 740 total hours of operation since the airplane was manufactured in 2017. The maintenance log entry describing the annual inspection of the engine noted, “Visually inspected turbo charger and lubricated as required.” No othermaintenance had been performed on the turbocharger since it was new. Review of the engine’s maintenance manual noted that every 100 and 300 hours the turbocharger should be inspected for oil leakage, mechanical wear and damage at the compressor blades, significant wear and grooves at the air intake, and damage concerning the functionality of the turbocharger and sealing. A review of Federal Aviation Administration service difficulty reports did not reveal a history of any other similar turbocharger failures.