What happened
On December 15, 2000, a Piper PA-46-350P (registration N429CA), a Malibu Mirage converted to a turboprop configuration, experienced a nose gear collapse while landing on runway 04 at Limoges Airport. The aircraft, operated by JetBill Limited, was performing a flight for transport purposes.
During the landing roll, the nose gear retracted, causing the three-blade propeller to strike the runway. The aircraft continued along the runway with the nose supported by the propeller before coming to a stop. The pilot reported that the landing was normal, with the main wheels touching down first and no heavy impact noted. The landing gear warning lights for the down-lock position were illuminated during the event.
The investigation
The investigation focused on the structural integrity of the engine mount, which had been modified to accommodate a PT6A-turboprop engine. This specific mount was part of a conversion kit designed by Rocket Engineering JetProp DLX.
Examination of the engine mount at the Toulouse Aeronautical Test Center revealed that the structure had suffered a static failure at three points. Investigators identified a 7 mm oxidized crack at the junction of three tubes near the nose gear actuator attachment point. This oxidation indicated that the crack was pre-existing and had not progressed for some time prior to the accident. A second 8 mm zone showed longitudinal crack progression that occurred during the landing on the day of the accident.
Further analysis showed that the failure originated from a torsional movement of the tube where the actuator is attached. The investigation also noted that the actuator attachment point was off-center to the right, which likely introduced torsional stresses. While the operator had performed visual inspections following a service letter from the conversion manufacturer, no cracks were detected during the most recent checks in September and November 2000.