What happened
On 24 September 2013, a Jetstream 4100, registration G-MAJA, was performing a commercial passenger flight when the crew encountered visibility issues during the final approach to Wick Airport. After losing visual contact with the runway, the crew initiated a go-around procedure. During this missed approach, the electronic flight instrument system (EFIS) displays experienced a momentary blanking, though the standby instruments remained functional.
Upon attempting a subsequent approach, a similar blanking event occurred, specifically affecting the co-pilot's displays. Due to the ongoing difficulties, the crew decided to divert to Aberdeen Airport, where weather conditions were more favorable. During the diversion, the crew also encountered difficulties with VHF communications. The aircraft eventually landed at Aberdeen without further incident, and there were no injuries to the three crew members or three passengers on board.
The investigation
Following the incident, the operator worked with the aircraft manufacturer to identify the source of the electrical issues. The investigation established that the blanking of the right EFIS display was the result of a loss of electrical power to the right essential busbar. To facilitate further study, the right power distribution unit was sent to the manufacturer.
Regarding the left EFIS displays, the manufacturer determined that their transient blanking was caused by an unrelated failure of the 'transzorbs', which are components within the windscreen heating system designed to protect avionics from static electricity. Additionally, the investigation found that the VHF communication difficulties were caused by two separate issues: a fault in the left communication unit and the loss of power to the right communication unit due to the aforementioned busbar failure.