What happened
During a forestry spraying mission for the Government of Newfoundland and Labrador, a formation of four PZL-M-18 Dromader aircraft was applying product to a forest block near the Buchans Airstrip. The weather was clear with excellent visibility and light winds. While performing a standard 'P-turn' maneuver at approximately 2100 NDT, the pilot of the third aircraft, C-GMVE, reported via radio that the engine was backfiring.
Following this report, the aircraft entered a spiral dive. The aircraft completed two tight left-hand turns in a near-vertical attitude before striking a stand of trees and hitting the ground. The impact caused the aircraft to explode and ignited a small forest fire. The pilot, who had over 7,000 total flight hours but only 30 hours on this specific model, sustained fatal injuries.
The investigation
Investigators examined the wreckage and the engine, a PZL-Aisz-62IR-M18, to determine the nature of the reported engine issue. While the pilot reported backfiring, the pilot of the following aircraft did not observe the engine's backfire valve actuate. Furthermore, the engine was producing enough power to maintain flight speed prior to the dive, as evidenced by the ability of the trailing aircraft to maintain spacing and the damage patterns on the propeller blades upon impact. No mechanical malfunctions were identified in the flight controls or engine components during the examination.
Technical review of the Aircraft Flight Manual (AFM) revealed that the procedures for a rough-running engine require the pilot to check several controls located on the lower right console and the left engine quadrant. Executing these steps requires the pilot to divert their gaze from the horizon to the cockpit and necessitates switching hands on the control stick to reach various switches.
Findings
- The aircraft entered a spiral dive and struck the ground due to undetermined reasons for the loss of control.
- The pilot may have been focused on troubleshooting the engine issue inside the cockpit, potentially leading to undetected inadvertent control inputs during the hand-switching required by the AFM procedures.
- The AFM lacks specific emergency guidance for engine roughness or failure during the extremely low-altitude operations characteristic of aerial application.
- The engine problem itself could not be definitively identified, though the engine remained functional enough to maintain flight speed during the initial phase of the event.