What happened
A local test flight departed from Moscow-Sheremetyevo Airport with the intention of testing battery endurance by deactivating all onboard generators. During the approach phase, while the aircraft was performing a turn at an altitude of approximately 400 meters, both engines ceased operation simultaneously.
Following the loss of power, the crew attempted to restart the engines; however, these efforts were unsuccessful. To prevent a more catastrophic impact, the captain decided to ditch the aircraft into the Ikshinskoye Reservoir, part of the Moscow Canal, situated roughly 18 km north of the departure airport. The aircraft became partially submerged in the water, but all five crew members were able to evacuate the wreckage without sustaining any injuries.
Findings
Investigations into the dual engine failure revealed that the electrical systems were non-functional as part of the planned testing procedure. A critical oversight occurred when the crew failed to account for the fact that the fuel transfer system was also inoperative during this test. Because the fuel transfer system required manual operation and the crew had neglected this requirement, the engines lost power, necessitating the emergency landing.