A FedEx Boeing MD-11 freighter flying from Almaty International Airport in Kazakhstan to Cologne-Bonn Airport in Germany made an unexpected diversion to Moscow Domodedovo Airport when the aircraft's automatic fire suppression system deployed on 8 June. FedEx says that inspections showed that no fire occurred in the cabin but that the system automatically deployed when its sensor network triggered a faulty indicator to pilots.

"[The aircraft] did divert to Moscow and it was for technical reasons with the fire suppression system but there was no fire on board," says FedEx.

FedEx says that the aircraft landed in Moscow in the early evening on 8 June, where it underwent a maintenance inspection that showed no signs of a fire happening on board. At 18:00 on 10 June, the MD-11 took off for Cologne to finish the flight with its cargo on board.

FedEx says it cannot determine the reason for the fault until its mechanics look into the issue further.

According to a FedEx video about the system, the fire suppression technology uses a network of infrared sensors that detects significant increases in the temperature of a freight container. A panel that shows the operational status of the fire suppression system and the position of the container that experienced a fire is located near the main deck crew door. In this case, the suppression system alerted the crew to a fire and automatically deployed its cargo injection system but it was a false alarm.

FedEx first told Flightglobal that it would install the bespoke fire suppression system it designed in-house on all of its Boeing MD-11 freighters and new Boeing 777Fs in October 2009. The system uses a network of heat-seeking sensors to detect fires caused by paper or lumber, gasoline or kerosene and combustible metals, such as lithium.

If the sensors detect a fire, it will alert the crew and cue an injector system that pierces a hole into a cargo container from above and sprays an argon-based, degradable, non-corrosive foam to extinguish the flames and to absorb toxic fumes. If the sensors detect an indicator of fire within a package of palletized cargo, the system will cover that pallet in a fire-retardant bag to restrict the level of oxygen around the freight.

Source: Air Transport Intelligence news