Fatal loss of control involving Jodel D92 ultralight near Dinan

Casualties unknown • Dinan - Trélivan, FR

A single-engine Jodel D92 ultralight crashed shortly after takeoff at Dinan-Trélivan, resulting in the death of the pilot.

What happened

On June 4, 2017, a Jodel D92 ultralight, identified as 68ADL, departed from runway 25 at the Dinan-Trélivan airfield for a private flight. Shortly after takeoff, the pilot turned left, passed near the edge of the airfield, and headed north. Approximately three minutes into the flight, the pilot reported being on the right-hand base leg via radio. During this period, witnesses reported hearing engine misfires.

An eyewitness observed the aircraft bank to the right and enter a steep dive. The aircraft struck the ground in a field located approximately 500 meters northeast of the runway threshold. The impact resulted in one fatality and the destruction of the aircraft.

The investigation

The investigation focused on the aircraft's mechanical state and the pilot's recent modifications. The pilot, an experienced EASA Part-66 aircraft mechanic, had recently replaced the original carburetor with an American-made AeroInjector fuel injection system to mitigate carburetor icing risks. The pilot was in the process of fine-tuning this new system.

On the day of the accident, the pilot performed ground engine tests with the assistance of three club members and found no anomalies. Investigators examined the wreckage and confirmed that the flight controls, fuel, lubrication, and cooling systems were intact prior to impact. The engine was receiving fuel, and the propeller was intact. Analysis of the engine showed that the AeroInjector system was configured with a fuel-air mixture that was too lean compared to the manufacturer's specifications. Additionally, witnesses suggested that following the carburetor change, the propeller was undersized for the aircraft's requirements.

Findings

  • The aircraft entered a steep dive at a low altitude, leaving the pilot with no opportunity for recovery.
  • The fuel-air mixture was set too lean due to improper adjustments of the new injection system.
  • The pilot was conducting flight tests to determine new propeller dimensions following the installation of the injection system.
  • The engine misfires heard by witnesses were a significant factor during the approach to the ground.

Probable cause

The accident resulted from a loss of control at a low altitude, likely linked to engine performance issues during the testing of a newly installed fuel injection system.

Frequently asked questions

What happened in the 2017-06-04 Jodel - D92 accident near Dinan - Trélivan, FR?

A single-engine Jodel D92 ultralight crashed shortly after takeoff at Dinan-Trélivan, resulting in the death of the pilot.

What aircraft was involved and where did it happen?

The accident on 2017-06-04 involved a Jodel - D92, registration 45ADL, at Dinan - Trélivan, FR.

What was the probable cause of the accident?

The accident resulted from a loss of control at a low altitude, likely linked to engine performance issues during the testing of a newly installed fuel injection system.

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