1970 Piper PA-28-180 Cherokee Accident Near Grandson, Switzerland (HB-OLS)

Accident Overview and Immediate Sequence of Events On 4 October 1970, a Piper PA-28-180 Cherokee, registration HB-OLS, was operating a private flight from Neuchâtel to Geneva. The aircraft was owned and operated by ATCOS’ Flying Group Genève. During the return leg, the pilot departed at 16:41 local time and climbed to 3,000 ft QNH. Near Concise, the pilot reported an abnormal engine noise and vibration. Although engine speed and instrument indications remained normal, attempts to correct the condition by changing engine speed were unsuccessful. The pilot then decided to land at Yverdon aerodrome for inspection. Shortly afterward, severe vibration and complete engine failure forced an emergency landing near Grandson. The pilot selected a field approximately 200 m long, recently seeded and well rolled, which he believed to be a meadow. In short final, he observed a raised path at the end of the field and turned 30° left while still airborne to avoid it. At 16:50, the aircraft landed in the field and rolled about 70 m while braking. It then left the rolled field and entered freshly ploughed ground, where the nose wheel sank into soft earth, breaking the nose gear leg. After sliding on its nose for a few metres, the aircraft overturned onto its back. ## Occupants, Aircraft, and Maintenance The pilot, born in 1944, held a private pilot licence issued on 3 May 1968 and was authorised for normal single-engine land aircraft up to 2,000 kg, including the Piper PA-28-180. His total experience was 88.05 hours and 306 landings, with 51 hours on the PA-28-180. Three passengers, born in 1946, 1947, and 1948, were aboard; none held aeronautical qualifications. The aircraft was a 1965 Piper PA-28-180 Cherokee, serial number 28-2339, powered by a Lycoming O-360-A3A engine and fitted with a Sensenich M76 EMMS-0-60 fixed-pitch two-blade propeller. It had been imported new from the United States in January 1966. At the time of the accident, the airframe had 1,576 hours and 5,098 landings. The engine had undergone a complete overhaul in April and May 1970 at 1,326.53 hours. A 100-hour inspection was completed on 3 September 1970 at 1,529.33 hours. The aircraft’s weight and centre of gravity were within approved limits. ## Damage and Engine Findings Two passengers sustained minor injuries; the pilot and the third passenger were uninjured. The aircraft was destroyed, while ground damage was insignificant. Examination of the wreckage showed extensive fuselage deformation, a crushed right wing leading edge, deformed wing attachments, a dented cabin roof, and a broken engine cowling front. The engine mount was distorted by the nose gear. Aileron and elevator controls remained functional, while rudder control was blocked by tail deformation. Landing gear flaps were set at 30°. Each fuel tank contained about 10 US gallons of fuel. Engine examination revealed that cylinder no. 3 had been torn from the crankcase. Its piston was broken at the pin, the pin was missing, and the lower part of the piston was absent. The freed connecting rod had struck and deformed the crankcase. All eight studs joining cylinder no. 3 to the crankcase were broken. Further inspection showed damage to the crankshaft and camshaft, deformation of connecting rod no. 3, and a piston failure caused by a sudden tensile load without an evident pre-existing defect. Segment expansion clearance was measured at 1.05 mm, below the prescribed 1.15–1.30 mm. The force required to remove intact connecting-rod bearing shells was only about 5 kg, and deposits were found between the shells and bearings. Significant fretting was present on the crankcase mating surfaces. The 28 May 1970 engine overhaul report did not record any findings related to the failure. ## Investigation Conclusions The pilot was licensed and qualified, and no evidence indicated a health-related impairment. The aircraft held valid airworthiness and admission certificates, and its maintenance complied with applicable requirements. The initial anomalies occurred over Concise, after more than half the Neuchâtel–Yverdon route had been covered. The decision to land at Yverdon was considered prudent because instruments did not indicate an imminent failure. The pilot’s actions after engine failure were judged good, and the landing was correct. The left turn made to avoid the raised path in final brought the aircraft into freshly ploughed ground after an insufficient rolling distance for a complete stop. The engine findings did not allow the cause or exact sequence of the failure to be established with certainty. However, marks on the crankcase indicated that connecting-rod pin no. 3 was still intact after the corresponding piston failed.