Accident Summary
On June 29, 2023, at 1222 eastern daylight time, a Diamond DA 40 NG, registration N44HH, was substantially damaged during a forced landing near Yorktown Heights, New York. The pilot, who was also the owner, sustained minor injuries. The flight was conducted as a personal flight under Title 14 Code of Federal Regulations Part 91.
Flight and Power Loss
The pilot intended to fly from Westchester County Airport (HPN) in White Plains, New York, to Orange County Airport (MGJ) in Montgomery, New York, for an annual inspection. While climbing to about 2,000 ft mean sea level (msl), the engine began losing power. The indicated power dropped to 75% and the climb rate decreased. The pilot reported the power loss to air traffic control. The power then fell to 68%, and the airplane began descending. The pilot searched for a suitable landing area and crabbed toward West Point as the airplane descended to 1,200 ft msl. Moving the throttle only changed the propeller pitch, not engine power. The pilot attempted a forced landing to a school field. During the approach, the airplane entered a steep right bank, the wingtip struck the ground, the airplane yawed right, and the left forward side of the nose impacted the ground before sliding to a stop. The empennage sustained substantial damage.
Engine Examination
The airplane was equipped with a 168-hp Austro Engine E4 diesel engine. At a salvage facility, the engine was examined. The turbocharger induction housing was found fractured in half with 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 showed no evidence of preimpact mechanical anomalies.
Turbocharger Analysis
The turbocharger was sent to the National Transportation Safety Board Materials Laboratory for further examination. Analysis revealed that the turbocharger housing had separated due to fatigue cracking. The fatigue cracks originated from the outer surface of the housing and propagated circumferentially. Steps on the fracture surface indicated that fatigue cracks on multiple planes had coalesced into one main crack. The remainder of the fracture surface displayed macro features consistent with overstress.
Maintenance History
According to the pilot and maintenance records, at the time of the most recent annual inspection in June 2022, the airframe and engine had accumulated 740 total hours since the airplane was manufactured in 2017. The inspection log entry for the engine noted: “Visually inspected turbo charger and lubricated as required.” No other maintenance had been performed on the turbocharger since new. The engine’s maintenance manual specified 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 affecting functionality and sealing. Review of Federal Aviation Administration service difficulty reports did not reveal a history of similar turbocharger failures.