What happened
On June 30, 2020, at approximately 20:16 local time, a modified Phoenix UH-22 helicopter, registration SP-HBOG, departed from a private airfield in Stawiska, near Strzegom, for a flight to a location approximately 7 km away. The aircraft was carrying a pilot and one passenger.
During the climb, reaching an altitude of roughly 150 meters, the aircraft encountered significant difficulties maintaining stability. Witnesses reported hearing abnormal noises coming from the engine and rotor system. At approximately 20:20 local time, the pilot lost control of the aircraft, which struck a field. The impact resulted in two fatalities and the total destruction of the helicopter.
The investigation
The PKBWL investigation focused on the aircraft's configuration and the pilot's qualifications. The investigation established that the aircraft was a custom modification of a decommissioned Robinson R-22 Beta by its owner, intended to reclassify the helicopter into the ultralight category. This modification included replacing the original seats and upholstery, as well as replacing the original NACA63-015 profile main rotor blades with lighter, uncertified composite carbon-kevlar blades featuring a NACA0012 profile. These replacement blades were produced by a company without aviation manufacturer certification and lacked any manufacturer markings.
Investigators also found that the pilot-owner lacked official qualifications to pilot the aircraft, being registered only under the K6E experimental subcategory. While the pilot had approximately 50 hours of flight time prior to the blade replacement, only 3 hours and 13 minutes of flight time had been logged using the new composite blades.
Findings
- The primary cause of the crash was the loss of control following abnormal engine and rotor system behavior.
- The aircraft was equipped with uncertified, unmarked composite main rotor blades that were not produced by an approved manufacturer.
- A physical inspection of the wreckage revealed that the trailing edge of one rotor blade had not been properly bonded near the root.
- The pilot had previously noted that the aircraft's handling characteristics had significantly deteriorated following the installation of the new blades.
- The pilot lacked the necessary official qualifications for the specific category of flight.