February 03, 2014
UPS is ready to start FAA certification testing of an active fire-suppression system fitted to the cargo carrier's new fire-resistant containers, preventive measures aimed in large part at protecting crews from lithium-type battery fires.
In a final pre-certification test in November 2013, the suppression system quickly extinguished a “Class A fire load test” that reached internal temperatures as high as 1,370F. Fueling the fire were 90 boxes each filled with 2.5 lb. of shredded paper and ignited by a Nichrome wire, per the FAA's test requirements. From a temperature standpoint, UPS says the fire approximated what would be experienced in a large-scale lithium battery fire caused by thermal runaway.
The containers and the dry aerosol potassium-based active suppression system are the products of a three-year research project by the UPS Independent Pilots Association (IPA) fire safety task force, a group formed after the fatal crash of a UPS Boeing 747-400F in Dubai in September 2010. United Arab Emirates investigators determined that a large fire developed in the palletized cargo on the “Class E” main deck in an area that included “a significant number of lithium-based batteries and other combustible materials.” The fire filled the upper deck and cockpit of Flight 6 with a stream of toxic smoke, less than 3 min. after the pilots received the first warning message. The heat from the fire damaged the flight-control systems.
Bob Brown, a UPS captain and member of the IPA task force, says some of its solutions were found in unusual places. “We had to go outside of aviation, into the automobile industry, Navy submarines and space programs to see how they handled in-flight fires,” says Brown. The IPA findings resulted in the development of new shipping containers made of a composite material called MacroLite, similar to that used in body armor, as well as an active fire-suppression system, the installation of emergency vision assurance systems and enhanced training.
Tests show that the containers, which weigh less and are more durable than legacy aluminum or polycarbonate-sided containers, can confine an internal fire of 1,200F (peak) for 4 hr. UPS initially ordered 100 MacroLite containers that were tested on 13,000 revenue flights over one year, with the containers proving to be “virtually indestructible” with no differences in loading and unloading, says Brown. While the new containers cost more than legacy models, he says, the added expense is offset by weight savings and reduced maintenance. The largest of the four, the AMJ, is 65 lb. lighter than legacy units.
Satisfied with the results of the pilot program, UPS ordered 1,821 of the fire-resistant units, the last of which were recently delivered. That is a small portion of the 30,000 shipping containers, also known as unit load devices (ULD), across the UPS network, but the company says that all legacy ULDs will eventually be replaced or retrofitted with MacroLite.
While the fire-resistant ULDs will theoretically give crews up to 4 hr. to land an aircraft carrying a fire-compromised ULD, an active fire-suppression system would address “high-energy scenarios” from lithium-metal and lithium-ion batteries as well as fuel cells and “any potential product that could be shipped in on our aircraft,” says Ed Walton, UPS director of engineering. He says an active fire-suppression system would also prevent “flash-over” and re-ignition of materials in the container when the door is opened by crew or firefighters and oxygen is reintroduced. Walton is optimistic that the FAA will certify the active suppression system by early summer.