What happened
On August 1, 2015, a Socata Rallye 235E, registration F-GUFZ, was performing a banner towing operation at the Béziers Vias airfield. After waiting for a Boeing 737 to land, the pilot was cleared to approach the banner catching area located south of runway 27.
Flying at a stabilized speed between 100 and 110 km/h with 30° flaps, the pilot successfully caught the banner. Following the procedure, the pilot initiated a go-around. However, the aircraft began to sink. Believing the banner might be snagged on the ground, the pilot immediately released the banner and verified the engine settings, which were set to full throttle, full rich, and full fine pitch. Despite these settings, the aircraft continued to descend, banking to the left before entering a stall. The wingtip struck the ground, causing the aircraft to ground loop and come to a halt. The pilot sustained one minor injury, and the aircraft was heavably damaged.
The investigation
The BEA examined the aircraft's engine, propeller, and flight data recorder (EDM700), finding no mechanical failures prior to the impact. While the engine and regulator performed according to manufacturer specifications, investigators noted that the propeller pitch control was found at one-third of the high pitch limit, rather than the required full fine pitch position for takeoff.
Radar analysis showed that the Boeing 737 had landed two minutes before the Rallye approached the catching area. Investigators also reviewed the aircraft's weight and balance. The estimated mass of the aircraft at the time of the accident was 937 kg, which exceeded the manufacturer's maximum takeoff weight of 900 kg specifically for banner towing operations.
Findings
- The pilot may not have correctly set the propeller to the full fine pitch position during the approach, resulting in insufficient power during the go-around maneuver.
- The aircraft was operating at a mass exceeding the 900 kg limit specified for banner towing, which likely degraded performance.
- The pilot's decision to release the banner to address a perceived snagging issue distracted from essential flight controls.
- The aircraft lacked the required cockpit label notifying the pilot of the specific 900 kg mass limitation for towing operations, as this information was located in the 'options' section of the flight manual rather than the primary limitations section.