What happened
On December 4, 2022, a privately operated Lancair 235, registration LN-XIC, experienced a runway excursion during takeoff from Trondheim Airport, Værnes. The pilot, while performing a takeoff roll, noticed the aircraft drifting to one side and focused on maintaining the centerline. During the acceleration phase, the pilot observed that the airspeed indicator was not behaving as expected, showing a nearly static reading between 0 and 20 knots despite the increasing speed.
Believing the airspeed was insufficient for takeoff, the pilot attempted to abort the departure by pulling the throttle to idle. During this maneuver, the aircraft's nose and right wing dropped, and the propeller struck the runway. The aircraft subsequently veered right, exiting the runway edge. The impact caused the nose gear to break and the right main landing gear to collapse, penetrating the right wing. There were no fatalities and no injuries to the pilot, who exited the aircraft unharmed.
The investigation
The Norwegian Safety Investigation Authority (NSIA) examined the aircraft's pitot-static system to determine why the airspeed readings were inaccurate. Technical testing conducted by HeliScan revealed a significant air leak within the pitot-static system. While the digital display in the cockpit showed no deviation when pressurized directly, the system failed to show "airspeed alive" until the test equipment reached approximately 70 knots. The investigation also noted that the aircraft, an experimental amateur-built model, lacked a pitot heat element to prevent icing.
Findings
- A leak in the pitot-static system prevented the airspeed indicator from displaying the correct indicated airspeed.
- The pilot failed to perform the "Air speed alive" check early in the takeoff roll, which likely would have revealed the instrument error before the takeoff was aborted.
- The decision to abort the takeoff while simultaneously pulling back on the control stick may have caused the aircraft to briefly lift off the ground before the subsequent loss of control.
- The aircraft's maintenance records showed no recent issues, suggesting the leak developed after the last flight on October 16, 2022.
Safety action
The NSIA noted that the incident was not initially classified as an accident by air traffic services, and the crash alarm was not activated. Furthermore, the investigation found that the proper procedures for preserving evidence were not followed, as the NSIA was not notified of the accident until 1.5 hours after the event, by which time the aircraft had already been moved from the site.