Accident to the Robin - DR400-160 registered F-GMRV on 13/09/2020 at Caussou (Ariège)

Cat. 2 investigation report: simplified-format report, adapted to the circumstances of the occurrence and the investigation stakes.

The pilot arrived at the club at the start of the afternoon to prepare the aeroplane in order to make an introductory flight with three passengers, lasting around 30 minutes. He checked the quantity of fuel on board. He estimated that three of the four tanks were half full, i.e. approximately 80 litres, corresponding to three flight hours and therefore compatible with the planned flight.
The pilot, accompanied by the passengers, took off at around 15:45 from Pamiers les Pujols aerodrome (Ariège) and headed south to fly over the Cathar castles.
After around 25 minutes, the plane was flying at an altitude of 6,500 ft in the vicinity of Montségur Castle, in the direction of Luzenac situated to the south-west. The pilot planned to fly back towards Foix Castle. He then observed an intermittent reduction in engine power and added that indicator lights had lit up on the warning bar. He could not remember which lights these were.
He operated the electric pump and stated that he switched from the main tank to the LH auxiliary tank. However, this seemed to make no difference. Considering the site he was flying over to be suitable for a forced landing, the pilot turned around to face the upward-sloping and obstacle-free area. He prepared the plane by extending the flaps then turned the fuel selector to the closed position. Just before contact with the ground, he positioned the mixture switch to idle cut-off and cut the magneto contacts.
The lack of fuel in the LH tank and the correct operation of the engine proven during a test bench examination led to the conclusion that the engine stopped following unpriming of the fuel system due to fuel depletion of the LH wing tank. These observations are not consistent with the statement of the pilot, who thought he had flown using the main tank.
It is very likely that the low fuel level warning indicator light for the LH front tank lit up during the flight.