What happened
On June 29, 2023, a Diamond DA40 NG, registration N44HH, was involved in an accident near Yorktown Heights, New York. The flight was being operated under Part 91 regulations for personal use. The pilot intended to fly from Westchester County Airport (HPN) to Orange County Airport (MGJ) for an annual inspection.
While climbing to a cruise altitude of approximately 2,000 feet mean sea level, the engine began to lose power. The pilot reported that indicated power dropped from 75% to 68%, and the climb rate decreased. After notifying air traffic control, the pilot attempted to regain power by adjusting the throttle, but only the propeller pitch changed.
As the aircraft descended to 1,200 feet mean sea level, the pilot searched for a landing site and began a forced landing toward a school field. During the maneuver, the aircraft entered a steep right bank, causing the wingtip to strike the ground. The airplane then yawed right and impacted the ground with the left forward side of the nose before sliding to a stop. The pilot sustained one minor injury, and the aircraft sustained substantial damage to the empennage.
The investigation
The aircraft was equipped with a 168-hp Austro Engine E4 diesel engine. An examination of the engine at a salvage facility revealed that the turbocharger induction housing was fractured in half and showed signs of an existing fracture surface. The propeller blades were found fractured near the hub. During testing, air pressure was heard exiting the glow plug holes when the propeller was rotated by hand.
Further metallurgical analysis of the turbocharger by the NTSB Materials Laboratory determined that the housing separation was consistent with fatigue cracking. The cracking originated from the outer surface of the housing and proceeded circumferentially. The examination showed that fatigue cracking on multiple planes had coalesced into a single main crack, with the remaining fracture surface showing features consistent with overstress.
Maintenance records indicated that during the June 2022 annual inspection, the turbocharger had been visually inspected and lubricated. No other maintenance had been performed on the turbocharger since it was new. The engine had accumulated 740 total hours of operation since its manufacture in 2017.