Engine failure during introductory flight leads to forced landing in France

Casualties unknown • Caussou, FR

A Robin DR400-160 experienced engine power loss and a forced landing on a hillside in Ariège due to fuel depletion in a wing tank.

What happened

On 13 September 2020, a Robin DR400-160, registration F-GMRV, was conducting an introductory flight near Pamiers les Pujols, France. The flight, operated by Aéroclub de Pami/Pujols, included the pilot and three passengers. After approximately 25 minutes of flight, while cruising at 6,500 feet near Montségur Castle, the pilot noticed an intermittent reduction in engine power and observed warning lights on the instrument panel.

In response to the power loss, the pilot activated the electric pump and switched the fuel source from the main tank to the left-hand (LH) auxiliary tank. Finding no improvement, the pilot identified a suitable area for an emergency landing on an upward-sloping, obstacle-free hillside. During the approach, the pilot extended the flaps and moved the fuel selector to the closed position. The aircraft touched down, bounced, and traveled approximately 20 meters before coming to a stop. The landing resulted in substantial damage to the aircraft, including broken landing gear.

The investigation

The BEA examined the wreckage, the engine, and the fuel system. While the pilot believed the aircraft had been operating using the main tank, investigators found that the LH wing tank contained only 0.6 liters of fuel, while the main tank still held 74 liters. Engine testing on a bench confirmed the engine performed normally when supplied with adequate fuel. The investigation also reviewed the pilot's statements regarding fuel management and the sequence of events leading to the power loss.

Findings

  • The engine stopped due to the unpriming of the fuel system caused by the depletion of fuel in the LH wing tank.
  • The pilot's belief that the aircraft was using the main tank was inconsistent with the actual fuel levels found in the tanks after the accident.
  • The pilot's focus on navigating the terrain and managing the flight path during the introductory flight likely diverted attention from identifying the specific nature of the fuel failure.
  • The pilot's decision to land in an obstacle-free area prevented serious injury to the occupants.

Probable cause

The engine failure was caused by fuel depletion in the left-hand wing tank, which led to the unprimable fuel system, compounded by the pilot's incorrect assumption regarding which tank was in use.

Frequently asked questions

What happened in the 2020-09-13 ROBIN - DR400-160 accident near Caussou, FR?

A Robin DR400-160 experienced engine power loss and a forced landing on a hillside in Ariège due to fuel depletion in a wing tank.

What aircraft was involved and where did it happen?

The accident on 2020-09-13 involved a ROBIN - DR400-160, registration F-GMRV, at Caussou, FR.

What was the probable cause of the accident?

The engine failure was caused by fuel depletion in the left-hand wing tank, which led to the unprimable fuel system, compounded by the pilot's incorrect assumption regarding which tank was in use.

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