Incident Overview
On 24 September 2013 at 1010 UTC, a Jetstream 4100 (registration G-MAJA) operated by an undisclosed commercial air transport carrier was conducting a passenger flight with three crew and three passengers. While on final approach to Wick Airport, the flight crew lost visual reference with the runway and commenced a go-around. During the missed approach, momentary blanking of the Electronic Flight Instrument System (EFIS) displays occurred; however, the standby instruments continued to operate normally.
Sequence of Events
During the subsequent approach, a similar event occurred, but only the co-pilot's EFIS displays were affected. The crew decided to divert to Aberdeen Airport, where weather conditions were better. During the diversion, the aircraft experienced difficulties with VHF communications, but the crew managed to land without further incident. No injuries were reported among crew or passengers, and the aircraft sustained no damage.
Technical Findings
The operator, in consultation with the aircraft manufacturer, determined that the blanking of the right EFIS display was caused by a loss of electrical power to the right essential busbar. The right power distribution unit was subsequently removed and sent to the manufacturer for investigation. The aircraft manufacturer indicated that the transient blanking of the left EFIS displays resulted from an unrelated failure of the 'transzorbs' installed in the windscreen heat system, which are designed to protect avionics equipment from windscreen static effects. The VHF communication difficulty was attributed to a separate fault on the left communication unit. The right communication unit was unpowered due to the right essential busbar failure.