What happened
During an aerial application mission, a PZL-M18A Dromader was performing routine herbicide spraying over a forested area. The pilot was circling a designated sector at approximately 400 feet above the ground when the aircraft suddenly entered a vertical descent in a spin. Following the impact with the ground, a fire broke out, destroying the aircraft and causing a spill of 2,040 litres of herbicide. The pilot, who was the sole occupant, sustained fatal injuries.
The investigation
The investigation focused on the aircraft's performance and the circumstances surrounding its weight. While the aircraft was found to be in compliance with regulations and no mechanical failures were identified, investigators examined the flight envelope of the PZL-M18A Dromader. It was noted that the aircraft was operating under a special weight exemption that allowed for a higher maximum takeoff weight than the manufacturer's original type approval.
Investigators also reviewed the pilot's experience, noting that while the pilot was a qualified commercial pilot, they had relatively limited experience with this specific aircraft type, with approximately 35 hours on the Dromader. Furthermore, discrepancies were identified between the aircraft's operating manual and the manufacturer's flight manual regarding weight limits and handling characteristics.
Findings
- The aircraft entered a spin and stalled at an altitude too low to allow for recovery.
- Operating the aircraft at a weight exceeding the manufacturer's type approval reduced the flight envelope and degraded handling characteristics.
- The increased weight led to a reduction in dynamic longitudinal stability and an increase in stall speed.
- The pilot's limited experience on the specific aircraft type may have hindered the ability to recognize and react to the onset of a stall.