What happened
On May 8, 2021, a Cessna T303 was conducting aerial photography flights in the vicinity of Zeltweg Airbase (LOXZ), Austria. To maintain a low airspeed for the photography sequence, the pilot operated the aircraft in a landing configuration with the landing gear and flaps extended.
Following the completion of the photography, the pilot attempted to retract the gear and flaps to proceed on a flight to Italy. However, the landing gear failed to retract, remaining in an unsafe position. After several unsuccessful attempts to retract the gear, the pilot contacted the Zeltweg tower to request permission for a touch-and-go maneuver on runway 26L.
The first touch-and-go was performed at 08:57 UTC. When the gear remained extended after the climb-out, the pilot requested a second touch-and and-go. During the second attempt at 09:07 UTC, the pilot applied the brakes two to three times while accelerating. During this process, the nose gear and the right main gear collapsed. This caused the propeller and the right wing to strike the runway surface. The aircraft eventually came to a stop approximately 300 meters from the runway centerline. Two occupants were on board, and both remained uninjured, though the aircraft sustained heavy damage.
The investigation
The Austrian SUB investigation focused on the mechanical failure of the landing gear system. Investigators examined the aircraft's hydraulic system, the electric motor for the hydraulic pump, and the electrical contactors. The investigation included a detailed technical analysis of the hydraulic pump motor, specifically looking at the condition of the brushes and the commutator, as well as inspecting the electrical contactors for signs of short-circuiting or electrical arcing.
Findings
- The primary cause of the gear failure was an electrical malfunction within the landing gear hydraulic system.
- Technical examination revealed that the contactor responsible for the hydraulic pump motor showed clear evidence of short-circuiting and electrical arcing (smudge marks and melted poles).
- The failure of the contactor prevented the hydraulic pump from providing the necessary pressure to retract the landing gear.
- The collapse of the nose and right main gear during the second touch-and-go was triggered by the application of the brakes during the acceleration phase of the maneuver.