What happened
On July 6, 2012, a British Aerospace Avro 146 Series RJ100, registration SE-DST, was performing a commercial passenger flight from Malmö/Sturup Airport in Sweden to Palma de Mallorca Airport in Spain. While descending toward the Spanish airport, the primary flight display (PFD) on the first officer's side suddenly went blank.
Shortly after the display failure, the crew detected the smell of electrical smoke, which was followed by visible smoke appearing in the cockpit. In response, the crew de-energized the electronic flight information system (EFIS), donned oxygen masks, and declared a MAYDAY emergency. Although the first officer initially struggled to communicate clearly with Air Traffic Control (ATC) while wearing an oxygen mask, the captain successfully established contact to request landing priority.
The smoke did not enter the passenger cabin, and the smoke cleared during the descent after the electrical system was shut down. The aircraft landed safely on runway 24L at 19:00 local time. The crew decided against an emergency evacuation, taxiing the aircraft to its parking stand, where passengers disembarked normally without injury.
The investigation
An investigation by the CIAIAC focused on the source of the smoke and the failure of the flight instrument. Upon inspection of the instrument panel, investigators found evidence of smoke around the ventilation holes of the first officer's PFD. A detailed disassembly of the unit revealed water marks, corrosion, and evidence of electrical arcing on several connectors within the low-voltage power supply.
The investigation also examined the maintenance history of the aircraft's EFIS displays. It was noted that the specific PFD unit had been replaced only weeks prior to the incident. Furthermore, investigators looked into the status of the isolation blankets located above the displays. While a manufacturer service bulletin existed to improve the fastening of these blankets, it was optional, and the operator had not implemented it on this aircraft.
Findings
- The primary cause of the incident was water entering the first officer's PFD unit, which led to a short circuit and subsequent electrical smoke.
- The water entered the unit because the isolation blankets were improperly positioned, allowing condensed moisture to drip directly onto the electronic components.
- The manufacturer had previously issued a service bulletin to improve the fastening of these blankets, but because the bulletin was not mandatory, the operator had not applied the modification to the fleet.
- The crew followed established emergency procedures, including the use of oxygen masks and the declaration of an emergency.
- The aircraft's airworthiness was maintained throughout the event, and no injuries were sustained by the 101 passengers or the crew.