History of the Flight
On 10 August 2016, a Jodel D140 C Mousquetaire registered F-BMBX was operated by a private pilot accompanied by a passenger, also a pilot. The flight originated from Castelnau-Magnoac (Hautes-Pyrénées). The pilot conducted a high and low reconnaissance of the Bergons mountain landing area in Vallon du Bergons, Salles-d’Argelès, in preparation for landing. The wind was light and erratic. Another aircraft had just landed. After a stabilized final approach, the pilot performed a three-point landing approximately 40 m beyond the runway threshold, slightly left of the centerline. During the landing run, the pilot applied right rudder to return to the centerline. A loud cracking sound was heard. The aircraft veered sharply left and came to rest at the runway edge with the left wing broken. The pilot described the landing as firm, typical for mountain landings, but not excessively so. The owner of the landing area observed the landing and considered it fine and not particularly hard. He witnessed the left wing break.
Additional Information
Site and Wreckage Information
The landing marks indicated a three-point run over about 30 m before the left landing gear track began to diverge. The first piece of wood debris was found nearby. Initial examination on site located the left wing failure between the main landing gear and the wing-fuselage junction. The wing was later examined at the BEA and an aircraft joiner’s workshop. Moisture measurements showed higher levels in the lower left rear flange near the wing root compared to the rest of the wing spar. The wing spar had failed at two locations: the left wing root and the left landing gear attachment. No anomalies in construction or gluing were found. Moisture traces were present on the lower wing fabric near the root and on the structure, as well as on inner fuselage sides. The highest moisture levels corresponded to failure areas. Mechanical tests on wood specimens indicated the wood was at least “first choice” or “premium choice,” complying with manufacturer requirements. Observations of fracture faces suggested the initial failure occurred on the lower left rear flange at the landing gear attachment.
Landing gear examination revealed both legs were deformed from significant upward stresses, with reduced angles between axle and shock absorber axes (normally 90°). Shock absorption quality was significantly degraded (friction, blockages, little lubricant). Permanent deformations indicated abnormally high stresses. No lubricator was found in the upper part of the shock absorbers, and lower lubricators were absent with deposits suggesting long-term absence.
Aircraft Information and Recent Maintenance
F-BMBX (serial number 142) was manufactured in 1965. It had been involved in four previous occurrences during landings, but examinations found no link to the wing failure. Logbooks showed no mention of hard landings. The pilot owned the aircraft since 2013 and had an approved maintenance program. In August 2015, the pilot and a mechanic conducted a 100-hour inspection, removing and overhauling the main landing gear after observing blistering. Shock absorbers were removed and reassembled. In autumn 2015, the pilot consulted knowledgeable individuals and realized deformations were likely from mountain operations. The aircraft did not fly between September 2015 and January 2016; during that period, the landing gear was removed again for overhaul. The legs were sent to a workshop for repair and reinforcement (metal welded to leading/trailing edges). The pilot repainted and reassembled. The airworthiness certificate was renewed on 15 January 2016. A 50-hour inspection occurred in early March 2016, and a 100-hour inspection in July 2016. The airframe had 7,224 flight hours; about 10 hours were flown between the July inspection and the accident. The pilot visually checked angles between axle and shock strut axes; no measurements were taken. The aircraft was occasionally used with skis (last time February to April 2016). No hard landing references in logbooks for previous 12 months. The aircraft was based at Aix-les Milles and hangared.
Pilot Information
The pilot held a valid private pilot license and SEP rating, with mountain ratings for skis (April 2011) and wheels (October 2011). He had about 1,025 flight hours, including 290 on type and 200 in mountains.
Meteorological Information
Météo France estimated the following at the accident site: northerly surface wind of 2 to 3 kt, visibility greater than 10 km, broken clouds at 5,800 ft, and temperature not specified.