What happened
On June 17, 2013, a Robinson R-44 Raven II helicopter departed from the Żerniki (EPZE) landing site for a flight toward Piotrków Trybunalski (EPPT). After receiving takeoff clearance from Krzesiny Tower, the pilot maintained contact with air traffic control until the aircraft reached point ECHO near Środa Wielkopola within the MATZ/EPKS airspace.
During the flight, the pilot observed that the GNS-530 avionics unit had shut down, resulting in a simultaneous loss of radio communication with Krzesiny Tower. In response to the emergency, the pilot initiated a 360-degree right turn at an altitude of 1,500 feet and activated transponder code 7600 to signal the radio failure. The pilot used a mobile phone to notify the Krzesiny controller of the situation and the intention to return to the departure site. After receiving permission, the pilot successfully landed back at Żerniki.
The investigation
The investigation focused on the failure of the onboard avionics. Following the landing, the pilot attempted to restart the GNS-530, which successfully powered on. The pilot then proceeded to Kobylnica (EPPK) for maintenance, maintaining full two-way communication with air traffic services during this transit.
Ground testing of the GNS-530 revealed a recurring failure pattern: the unit would operate for approximately 25 minutes before automatically shutting down for another 25-minute interval. Notably, this was only the second flight following a recent repair of the same unit, which had previously been serviced for poor transmission and reception quality. The malfunctioning unit was subsequently removed and sent for warranty service.