Incident Overview
On 22 May 2016, a glider pilot conducted a preflight inspection of an SZD-50-3 Puchacz glider at EPEL airfield and reported the aircraft fully serviceable. The pilot then performed a winch launch for a planned thermal flight in accordance with task B/8-1. All phases of the winch launch proceeded without anomalies.
In-Flight Control Issues
After releasing the winch cable and during acceleration, the pilot experienced significant resistance in the elevator control and was unable to reduce airspeed below 100 km/h despite adjusting the trim. At an altitude of 380 meters, the pilot executed a gentle 180-degree right turn back toward the airfield and landed on runway heading 100 degrees. Upon landing, the elevator control resistance ceased. The landing was completed without damage to equipment. The glider was subsequently towed to the hangar and an appropriate entry was made in the aircraft technical log.
Post-Flight Examination
A post-incident inspection revealed that the restriction of elevator movement was caused by partial blockage of the control stick travel by the buckle of the fifth seatbelt (the crotch strap used during aerobatics) in the rear cockpit. This strap, when not in use, should be secured by hooking its buckle onto the attachment point on the seat pan. The investigation found that the strap was routed over the fuselage frame and into the control stick compartment, with the buckle positioned near the control console.
Findings and Causal Factors
The investigation determined that the partial blockage of the control stick by the fifth seatbelt buckle resulted from a careless preflight inspection, which failed to detect that the fifth seatbelt was not secured and was improperly positioned in the area of the control stick installation.