What happened
On 6 February 2019, an Airbus A330-243, registration G-TCCF, was operating a commercial passenger flight from Frankfurt, Germany, to Cancun, Mexico. While cruising over the North Atlantic Ocean, the commander was performing duties as pilot monitoring. During this time, a cup of coffee, which was being served without a lid, was knocked over onto the commander's tray table.
A small amount of the liquid spilled onto the aircraft's audio control panel (ACP1). While the liquid dried quickly, it caused an immediate malfunction affecting VHF transmissions and public address capabilities. Shortly after, the unit became extremely hot, emitting an electrical burning smell and smoke. Approximately twenty minutes later, the co-pilot's audio control panel (ACP2) also failed and became hot enough to melt a button. Due to the smoke and the significant loss of communication between the crew, the commander decided to divert the aircraft to Shannon, Republic of $Ireland$.
During the diversion, the crew utilized supplementary oxygen masks to manage the cockpit environment. The aircraft landed safely in Shannon with no injuries to the 11 crew members or 326 passengers.
The investigation
The investigation focused on the cause of the electrical failures and the subsequent smoke. Engineering inspections of the removed audio control panels revealed that the failures in ACP1 were directly attributed to liquid contamination. While the cause for the failure of ACP2 remained less certain, the investigation examined the cockpit environment and the suitability of the service items used.
Investigators noted that the cups used by the operator on this route were difficult to place into the aircraft's dedicated cup holders. This difficulty, combined with the presence of fold-out tray tables, led to the drink being placed in a vulnerable position. The investigation also highlighted that the lack of lids on the cups contributed to the volume of liquid reaching the electronics.
Findings
- The primary cause of the electrical malfunction and smoke was liquid contamination from the spilled coffee causing short circuits in the audio control panels.
- The design of the cups used made them difficult to secure in the cockpit cup holders, discouraging their use.
- The use of open cups without lids allowed the liquid to reach the center console electronics.