What happened
On June 8, 1993, at approximately 17:15 local time, a Piper PA-28-161 "Warrior" with registration HB-PIB departed from Lausanne-La Blécherette Airport. The aircraft was operated by the motor flight group of the Vaud section of the Swiss Aero Club (AéCS) for a private flight training exercise involving cross-country landings. The pilot, an instructor, and a student were aboard.
During the takeoff roll, the instructor noticed the aircraft deviating slightly to the right, though he confirmed the student had not inadvertently applied brake pressure. Shortly after becoming airborne, the crew felt significant vibrations. An airfield official radioed the instructor to report that something appeared to have detached from the aircraft, though details were unclear.
The instructor took control and performed a low pass over the runway. Observers on the ground confirmed that the right main landing gear leg had separated, hanging only by its hydraulic brake line. Following consultations with airfield management, the decision was made to divert to Geneva-Cointrin Airport. To mitigate risk to people or infrastructure in case the gear failed completely, the instructor flew over Lake Geneva toward the emergency site.
Upon arrival at Geneva, the aircraft performed two low passes to allow ground crews to assess the damage and identify a safe touchdown point on runway 05. The emergency services were prepared for intervention. The aircraft landed without major incident, though the right wing sustained damage. Both crew members exited the aircraft unharmed.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) examined the physical evidence and operational context. The landing gear leg was sent to the EMPA materials testing laboratory for analysis. The investigation also reviewed the condition of the runway at Lausanne-La Blécherette, which had undergone recent repairs.
Findings
The primary cause of the accident was a fatigue fracture in the right main landing gear. Laboratory analysis revealed that corrosion pits, likely caused by chloride compounds such as de-icing salt, played a decisive role in initiating the crack. The fracture grew under relatively high nominal stress before failing catastrophically.
Contributing factors included the condition of the runway at Lausanne-La Blécherette. The surface had significant irregularities due to repairs, with level differences of up to 2 cm between filled sand and grass. These uneven surfaces subjected the landing gear to severe shock loads during takeoff and landing. The airfield authorities had correctly identified this issue and proceeded with resurfacing the central strip.
The instructor's decision to divert to Geneva and fly over the lake was deemed prudent, ensuring that a potential total failure of the gear would not endanger people or property on the ground.
Safety action
Airfield management at Lausanne-La Blécherette implemented immediate corrective actions by resurfacing the central runway strip to eliminate the uneven terrain that contributed to the shock loads on the aircraft's landing gear.