History of the Flight
On 17 March 2021, around 11:35 local time, a Cessna 172 S registered F-HFBR was conducting a local instruction flight from Bordeaux-Mérignac airport. The flight, operated by the Cercle Aéronautique des Personnels de l'Aéroport de Mérignac (CAPAM), was a standardization session due to recent avionics installation. The trainee pilot and instructor took off at 10:20 from runway 05. The outbound leg to Mimizan aerodrome proceeded without incident.
During the return, after a coastal route flown on autopilot at 1,000 to 1,500 ft, the pilot headed toward runway 05. Air traffic control requested a hold at the "SA" reporting point at 1,500 ft because another aircraft was on an IFR approach. The pilot disconnected the autopilot and began the holding pattern. Four minutes later, both occupants noticed an uncommanded reduction in engine speed. A drop in oil pressure and rise in cylinder temperature confirmed an engine failure. The propeller stopped in a horizontal position.
The instructor took control and aimed for the threshold of runway 05. He believed he transmitted a "Mayday" call, but it went unnoticed by the controller, possibly due to simultaneous transmissions. Nevertheless, the controller recognized the emergency from other radio exchanges, including the instructor's report of an engine flame-out. The instructor spotted a field with low crop about 2 nautical miles from the runway threshold, fully extended the flaps, and landed in the field. Upon touchdown, the nose landing gear sank into loose soil and broke. The aircraft tipped forward and overturned. The emergency locator transmitter activated. A nearby helicopter pilot, who had heard the distress calls, landed near the site to assist. Both occupants, unharmed, evacuated without assistance.
Additional Information
The flight path was recorded by the aircraft's GNSS computer up to ground contact, with the wreckage position matching the last recorded point. Meteorological conditions estimated by Météo-France included visibility greater than 10 km, surface wind from 020° to 050° at 10 knots gusting to 20 knots, temperature 12°C, dew point 2°C, and QNH 1031 hPa.
The instructor, aged 69, held a Private Pilot Licence (Aeroplanes) and an instructor rating. He had accumulated 16,820 flight hours, including 5,819 hours of instruction, with 42 hours in the preceding 90 days (25 on F-HFBR). The trainee pilot, aged 47, held a PPL(A) issued in 2017, with 132 total flight hours (128 on Cessna 172), 5 hours in the last 90 days, and about 3 hours in the last 30 days.
Wreckage and Engine Examination
The wreckage lay inverted in a ploughed field. The airframe sustained minor damage, while the propulsion system was more heavily damaged. The propeller blades showed little deformation, consistent with an in-flight shutdown. Fuel was present in the wing tanks. Visual examination of the engine revealed corrosion on the casing and cylinder barrels. Detailed examination showed extensive contamination of the lubrication system with a mixture of engine oil and fine metal particles. This contamination reduced lubricating power, causing damage to the front half-bearings, unusual friction marks on all pistons, and incipient fusion of the No. 1 cylinder piston. The metal particles originated from significant wear on the camshaft and several hydraulic lifters. According to the engine manufacturer, such damage is gradual and typically caused by corrosion pitting, exacerbated by engine age, prolonged shutdowns, short operating periods, and humid conditions. The manufacturer noted that this damage is normally detectable during oil filter inspection at scheduled maintenance.
Maintenance History
The Lycoming IO-360 L2A engine (serial L-28126-51A) was installed on the aircraft in December 2007 with zero hours. The aircraft had undergone various inspections and a period of downtime between April and July 2020 for avionics installation, during which no preservation measures were taken. An annual inspection in September–October 2020, following a new maintenance program, noted no particles in the oil filter and no corrosion. However, the inspection did not include cutting open the oil filter as specified in Service Bulletin No. 480F, which was made mandatory by the maintenance program. The engine had accumulated 2,224 hours at that inspection.