SZD-55-1 collision with parked aircraft at Bad Ragaz airfield during aerotow launch
On March 30, 1992, a PZL Bielsko SZD-55-1 experienced an incident during an aerotow launch at Bad Ragaz airfield in Switzerland. Shortly after the tow began, the glider's right wing touched the ground, causing it to veer off the paved runway. The pilot released the tow cable but was unable to stop the glider, which collided with a parked Mooney aircraft. The glider sustained minor damage, while the Mooney was significantly damaged. The pilot suffered minor injuries. The investigation identified improper aileron control installation as a contributing factor.
- Aerotow takeoff roll: During an aerotow departure on runway 12, the SZD-55-1 began its takeoff roll in variable 5–10 kt wind for the pilot’s seventh conversion flight on type.
- Misrigged aileron control: The right aileron drive lever had been incorrectly installed at the factory, giving both ailerons excessive positive setting and reducing roll control effectiveness.
- Right wing contacts ground: Shortly after the towplane began to pull, the glider’s right wingtip touched the ground in the grass area beside the paved runway.
- Veer off runway: The right wing was decelerated by the low grass and, despite full opposite aileron, the glider yawed and departed the hard-surface runway after about 30 meters.
- Tow cable released late: After being unable to raise the wing, the pilot released the nose hook tow cable only after roughly 50 meters of ground run, by which time the glider was already off the runway.
- Wheel brake not used: With only about three seconds remaining before impact, the pilot did not apply the wheel brake and the glider continued rolling unchecked toward a hangar.
- Crash - minor injury: After a total ground roll of about 100 meters, the unbraked glider collided heavily with a parked Mooney M20J, causing major damage to the Mooney, minor damage to the glider, and minor injury to the pilot.