Accident Details
On 22 May 2020 at 15:00 local time, a Cessna 172S (registration HB-TLZ) operated by the Groupe de Vol à Moteur de Porrentruy was landing at Lausanne-La Blécherette (LSGL). The pilot, a Swiss citizen born in 1971 holding a PPL(A) issued by the Swiss Federal Office of Civil Aviation, had last landed at this airport on 19 April 2019. The flight originated at Bressaucourt (LSZQ) and was conducted under VFR.
During the approach to runway 18 from the north, the aircraft touched down and bounced. After the pilot pushed the nose down, the nose wheel made hard contact with the runway, followed by two more bounces on the nose wheel. The pilot then initiated a go-around and completed a circuit before landing again on runway 18. During the go-around, the pilot felt a friction sensation when pulling back on the pitch control.
After parking, the pilot performed a visual inspection but found no apparent damage. The aircraft was not inspected by a mechanic. The pilot then flew back to Bressaucourt. The pilot informed the fleet manager of the hard landing but did not record the event in the aircraft's logbook. Structural damage was discovered two days later during a pre-flight inspection by an instructor from the flying group.
Meteorological and Aerodrome Information
At 14:30 local time, Lausanne-La Blécherette weather station reported a QNH of 1023 hPa and wind from 200° at 5 knots. Runway 18 has a slope of 2.50% on the first 414 meters.
Operational Procedures
According to Section 4 of the Cessna Model 172S Flight Manual, the landing procedure states: "Power should be at idle when the main wheels touch the ground. The main wheels should touch the ground before the nose wheel. The nose wheel should be lowered gently onto the runway after speed has diminished to avoid unnecessary loads on the nose wheel."
Investigation Findings
The Swiss Transportation Safety Investigation Board (STSB) conducted a summary investigation. The pilot had not landed at Lausanne-La Blécherette for over a year and was likely surprised by the downhill slope during the flare, leading to three bounces that placed high loads on the nose wheel. The decision to perform a go-around was understandable but initiated too late; it should have occurred after the first bounce.
The accident was due to an inadequate flare causing bounces with high loads on the nose wheel, resulting in structural deformations of the fuselage. The friction sensation in the pitch control during the go-around, caused by deformations of the airframe (particularly the firewall), should have alerted the pilot, who only performed a visual check. A mechanic's inspection would likely have discovered the structural issue. The decision to fly back to Bressaucourt and not record an entry in the logbook could have had serious consequences.