What aircraft was involved and where did it happen?

The accident on 2015-08-22 involved a Robin ATL, registration F-GGXF, at Visan (84), FR.

What was the probable cause of the accident?

The accident was caused by a reduction in engine power, likely due to fuel delivery issues or throttle linkage failure, which led to an aerodynamic stall at a low altitude.

Loss of control following engine power loss in Robin ATL

A Robin ATL aircraft crashed into trees shortly after takeoff at Valréas Visan aerodrome due to a loss of engine power and subsequent stall.

What happened

On August 22, 2015, a Robin ATL, registration F-GGXF, departed from the unpaved runway 02 at Valréas Visan for a local flight. The aircraft was carrying a pilot and one passenger. During the initial climb, approximately 20 meters before the end of the runway, the aircraft experienced a sudden decrease in airspeed. The aircraft banked to the right and lost altitude. The pilot was unable to regain control, and the aircraft collided with trees and the ground approximately 500 meters beyond the runway threshold. The impact resulted in the destruction of the aircraft and caused slight injuries to the pilot and passenger.

The investigation

The investigation focused on the engine performance and the aircraft's configuration during takeoff. While the pilot reported using a 10° flap setting, the wreckage showed the flaps were extended. Video analysis of the takeoff confirmed the aircraft was climbing at 100 km/h with a 13° pitch attitude at the mid-point of the runway, but the loss of control occurred seconds after the final video frame.

Technical examinations of the engine revealed several critical issues. The throttle control had become disconnected from the carburetor lever, which would cause the engine to default to idle power. Additionally, the fuel lines to the carburetor were cracked, and the fitting between the mechanical fuel pump and the carburetor was improperly seated, which had allowed fuel to leak.

Furthermore, the investigation found that the aircraft was approximately 20 kg overweight, and the pilot had not performed a weight and balance calculation. It was also noted that the pilot had been performing his own maintenance since March 2010 without the required Part 66 license or authorization, and the aircraft's airworthiness certificate was invalid.

Findings

The primary cause of the accident was a loss of engine power leading to an aerodynamic stall at a low altitude.
Fuel delivery to the carburetor was likely compromised by cracked fuel lines and an improperly installed pump fitting.
The disconnection of the throttle linkage may have caused the engine to revert to idle power.
The aircraft was operating in a slightly overweight condition, which contributed to degraded performance.
The pilot's use of a high pitch attitude during the initial climb, combined with a slight tailwind and increased weight, may have contributed to the loss of airspeed.