What happened
On August 28, 2003, an Esqual VM1P ultralight, registration CS-ULL, departed from Beja Aerodrome for a two-hour recreational flight under visual flight rules. Upon returning to the aerodrome, the pilot performed a landing on runway 17, utilizing a 20° flap setting. At the time of the landing, the wind was recorded at 240° with a strength of 18 knots.
The pilot landed in the final fifth of the runway, an area noted to be in a degraded condition. While attempting to decelerate and taxi toward the hangar, the pilot applied the brakes but experienced a failure of the left brake. To prevent the aircraft from pivoting sharply to the right, the pilot released pressure on the right brake and shut down the engine ignition and magnetos. Despite these efforts to maintain the centerline, the aircraft drifted off the runway, crossing the end of the pavement and striking an earthen embankment. The pilot escaped the accident uninjured.
The investigation
The GPIAAF investigation examined the aircraft's maintenance history, the meteorological conditions, and the pilot's actions. The investigation found that the aircraft's Pilot Operating Handbook (POH) specified a maximum crosswind component of approximately 15 knots, meaning the actual wind conditions exceeded the manufacturer's operational limits. Additionally, the investigation noted that the pilot used a 20° flap setting, whereas the POH recommends a minimum flap setting for crosswind landings.
Regarding the mechanical failure, investigators determined that the pilot's heavy application of the brakes to counteract the high speed and wind likely caused the left brake pedal to deform. This deformation resulted in a loss of tension in the control cables, leading to the perceived failure of the left brake. The investigation also noted that the aircraft landed on the degraded portion of the runway and that the engine was shut down prior to the impact with the embankment, as evidenced by damage to only one propeller blade.
Findings
- The primary cause of the accident was the strong crosswind conditions that exceeded the aircraft's operational limits.
- The pilot's failure to utilize the full length of the runway and the use of a higher-than-recommended flap setting for crosswind conditions were contributing factors.
- The aircraft sustained significant damage, including deformation of the landing gear, a fractured propeller blade, and damage to the engine mount and radiator.