What happened
On March 14, 2016, an instructor pilot was conducting a training flight as part of a private pilot certification program for a student. The flight was organized under a contract between Ural Helicopter Company and a Russian citizen. The mission involved performing specific training exercises, specifically focusing on landing at restricted-size landing sites within a 5km radius of the Barantal landing site, which served as the helicopter's home base.
The flight was intended to be conducted under Visual Flight Rules (VFR) within Class G airspace. Prior to the first of two planned sorties, the instructor pilot and the student performed a pre-flight inspection of the Robinson R-66. According to the instructor, no technical issues were identified during this inspection, although no formal entry regarding the aircraft's condition was recorded in the flight log.
At the time of departure, the aircraft's takeoff weight was 945 kg, which was within the maximum takeoff weight limit of 1225 kg specified in the Pilot's Operating Handbook. The center of gravity was measured at 2465 mm, falling within the permitted range of 2310 mm to 2600 mm. The aircraft was not refueled for this mission, as the 210 liters of TS-1 fuel remaining from a previous flight were deemed sufficient for the planned exercises.
The investigation
During the investigation, it was noted that while the instructor pilot reported no technical defects during the pre-flight inspection, there was no corresponding entry made in the aircraft's technical logbook regarding the inspection results.