Factual Information
On 12 July 2013, at approximately 08:18 local time, a Flight Design CTLS-ELA aircraft, registration HB-WYS, operated by Club Aéronautique Swissair Genève / CASG, was involved in a serious incident near Gland, Switzerland. The aircraft was performing a private visual flight rules (VFR) flight from La Côte airfield (LSGP) to Neuenburg (LSGN). The pilot, a Swiss citizen born in 1958, held a private pilot license (PPL(A)) issued by the European Aviation Safety Agency (EASA), with a total of 834 flight hours, of which 19:17 hours were on the accident type.
Events Leading to the Incident
The pilot refueled the aircraft with 20 liters of AVGAS UL 91 in each wing tank before departure. During the initial engine check, no irregularities were noted. The first takeoff from runway 04 was made with flaps set to 15° and an engine speed of 5200 RPM. After a right turn and reduction to 5000 RPM, a "FUEL PRESSURE LOW" warning appeared on the right display. The pilot retracted the flaps, the warning disappeared, and he completed a traffic pattern landing with flaps at 35° without further alarms. After taxiing, he took off again for the intended flight to Neuenburg, again with flaps 15° and takeoff power at 5200 RPM. While overflying trees at the runway end, the engine began to stutter and a warning (possibly "oil pressure failure", though the pilot was unsure) appeared. The pilot lowered the nose to maintain 62 knots, then the engine stopped abruptly.
Emergency Landing
The pilot performed an emergency landing on a grain field. The pilot remained uninjured. The aircraft sustained no damage. Minor crop damage occurred to the field.
Investigation Findings
The Swiss Transportation Safety Investigation Board (STSB) investigated the incident. The fuel system of the HB-WYS was examined. According to the schematic, no electric fuel pump was installed. The return fuel line from the fuel distributor was routed to the gascolator (fine filter/water separator). Additionally, the fuel line at the gascolator outlet was connected via a right-angled nipple to the mechanical fuel pump. The STSB concluded that the serious incident was due to engine stoppage following insufficient fuel supply, resulting in an emergency landing. The design of the fuel system was considered to be the cause of insufficient fuel supply because it did not allow the elimination of air bubbles present in the fuel lines.
Meteorological Conditions
At the time of the incident, weather was clear with 30 km visibility, wind from 60° at 2 knots, temperature 18°C, dew point 11°C, and QNH 1018 hPa. There was a risk of moderate carburetor icing in cruise flight.
Aircraft Information
The aircraft was a Flight Design CTLS-ELA, a high-wing composite aircraft with fixed tricycle landing gear, manufactured in 2011. It was powered by a Rotax 912 ULS engine (73.5 kW) and a Neuform 3-blade propeller. Total operating hours at the time were 266:09 hours. The takeoff mass was approximately 500 kg, within the maximum allowable takeoff mass of 600 kg. The center of gravity was within limits.