1964 Jodel U2-MFGZ Accident Near Lausanne (HB-SOV)

Accident Overview and Investigation Approval On 15 June 1964, a Jodel U2-MFGZ with registration HB-SOV crashed near the Lausanne airport. The Federal Commission for Aircraft Accident Investigations approved the investigation report of 27 November 1964, with one amendment, by circulation on 12/22 January 1965. The accident occurred during a visual flight rules (VFR) flight from Kloten to Prangins. The pilot was surprised by an engine stoppage while attempting to switch from an empty fuel tank to another tank that still contained fuel. While flying over the Blécherette airfield, the pilot could not reach the field and the aircraft capsized during landing in a field west of the airfield. Both occupants were slightly injured, and the aircraft was seriously damaged. The engine stoppage was very likely caused by a handling error. ## Personnel and Aircraft The pilot was born in 1916 and held a private pilot licence issued on 15 July 1961, valid until 17 January 1965 for normal single-engine land aircraft of 1 to 5 seats up to 2,000 kg. The licence listed transitions for the Stinson 108-2, Cessna 172 and 175, and Cherokee PA-28, and included a radio-telephone extension. The pilot began training on 11 January 1961 at Kloten. Total flight experience was about 280 hours and 1,132 landings, including 62 hours and 218 landings in HB-SOV. In the preceding three months, the pilot had about 33 hours and 79 landings, including about 4 hours and 11 landings in the accident aircraft. The pilot began training at age 45 and was described as having average general flying aptitude and a nervous disposition. The passenger was born in 1917 and had no aeronautical title or training. The aircraft was owned and operated by Motorfluggruppe Zurich. It was a Jodel U2-MFGZ equipped with a Continental C 90-12F engine and a fixed-pitch, two-blade McCauley metal propeller. The aircraft number and year of manufacture were 1131/17 and 1961. Its certificate of airworthiness and admission to traffic was issued on 3 August 1961 and valid until 11 July 1964. The aircraft was a low-wing, wooden, two-seat side-by-side touring aircraft with fixed landing gear and a tail wheel. It was the prototype of a modified version of the Jodel D-11 and its derivatives, with modifications including an increased fuselage section, flaps, and a new fuel system. ## Fuel System and Weight The fuel system consisted of two non-communicating 55-litre tanks embedded in the wings on either side of the fuselage. A two-way valve between the seats allowed use of either tank. The valve had a semi-circular dial marked TANK RECHTS, TANK LINKS, and ZU. The 6 o'clock position corresponded to the right tank, 9 o'clock to the left tank, and 12 o'clock to closed. Separators with drains were located at the low point of the system. Fuel supply was provided by a mechanical AC pump and an auxiliary electric Bendix pump. The checklist required the auxiliary pump to be engaged on the ground before engine start and takeoff, and in flight before landing and each tank change. Fuel quantity was indicated by electric gauges on the instrument panel, which also had a fuel pressure instrument and a red warning lamp near the auxiliary pump switch. At the time of the accident, the maximum weight was 700 kg and the actual weight was about 615 kg. The centre of gravity was within prescribed limits. ## Weather and Location A cold front crossing the Alps during the night of 14 to 15 June caused widespread showers on the northern side of the Alps, with marked improvement during the morning of 15 June. Along the route, the sky was overcast to very cloudy between 1,500 and 2,000 m, visibility was 8 to 20 km, and wind was 5 to 10 knots, variable on the ground and from the west at 1,500 m. Temperatures and relative humidity at 1350 HEC were: Zurich 15°C/69%, Olten 19°C/64%, Berne 16°C/61%, Romont 17°C/61%, and Lausanne 16°C/61%. The accident occurred on the north-western periphery of Lausanne, in the municipality of Prilly. The aircraft landed 400 m west of threshold 01 of the grass runway (730 x 100 m) at the Blécherette airfield, in a field oriented parallel to the runway and usable for about 300 m on the day of the accident. The impact point, coordinates 536.550/154.900, altitude 560 m/M, was 60 m below the airfield level.