What happened
On July 10, 2018, a PIPER PA32R, registration OY-JAD, was conducting a private pleasure flight from Vesthimmerland (EKVH) to Roskilde (EKRK). Approximately 20 minutes into the flight, while cruising at 5,000 feet between the cities of Hobro and Randers, the aircraft experienced a sudden electrical failure. This failure progressed sequentially, causing the loss of engine instruments, radios, and the transponder within one minute. During this period, only the standby instruments and a portable GPS with an independent battery remained operational.
In response to the emergency, the pilot diverted the aircraft toward Aarhus (EKAH), where emergency services were available. Because the aircraft's radio systems were non-functional, the pilot communicated with Copenhagen Briefing via a mobile phone call to declare the emergency. As the aircraft approached Aarhus, the pilot used a mobile phone to contact the control tower. During this communication, the controller alerted the pilot that the landing gear had not been deployed. The pilot subsequently performed an emergency gear extension, which was confirmed by the controller. The aircraft landed safely and taxied under its own power to a parking position.
The investigation
The technical examination of the aircraft focused on the cause of the electrical depletion. Investigators determined that the aircraft battery had become discharged, with the voltage dropping to 22.2 volts. The investigation identified that the generator drive belt was loose and incorrectly installed, with the V-section facing the wrong direction. Upon reconnecting power, the aircraft's warning lights for alternator inoperative and low bus voltage both illuminated, confirming the underlying electrical system fault.