GCAA: 747 vibration risk to lithium-ion cargo?

Air accident investigators at the General Civil Aviation Authority (GCAA) of the United Arab Emirates are urging the industry to examine the role of vibration in large aircraft to detemine whether it could contribute to lithium-ion battery cargo fires.

The release today of the final report concerning the fatal crash of a United Parcel Service (UPS) B747-400 in Dubai on September 3, 2010, details the facts concerning the accident, and makes recommendations addressing air cargo fire safety.

The UPS Boeing 747-400 flying between Dubai International Airport and Cologne Bonn Airport crashed close to Dubai airport, killing the two crew members.

In October 2010, the US Federal Aviation Administration (FAA) issued a safety alert for operators highlighting the fact that the cargo on board that flight contained a large quantity of lithium-ion batteries and that Halon 1301 had been inefficient in fighting the fires. The FAA subsequently issued a restriction on the carrying of lithium batteries in bulk on passenger flights.

The GCAA’s final report states that even now its investigators have been unable to determine the initiating action that resulted in the cargo fire.

“One line of testing outside the scope of this investigation was the investigation of the possible effect of structural-acoustic coupling to determine the acoustic principle sources and transmission paths for
airframe junction vibration transmission, the effect of multi-frequency phased vibration of the fuselage structure caused by tonal disturbances, either engine derived or by airbourne structural excitations, affecting the modal characteristics and fuselage dynamic responses,” states the report.

Structural-acoustic coupling phenomenon in an aircraft fuselage is a known characteristic of aeroelastic structures and yet the vibration and acoustic signatures of large aircraft cargo areas are not well understood.

The GCAA said the FAA working with European colleagues at EASA and Boeing should evaluate the Boeing 747 Freighter/Combi aircraft Class E cargo compartment for a structural acoustic coupling phenomena in the aircraft fuselage.

Further, it urges the US air accident investigation bureau at the NTSB, the FAA and EASA fire test divisions perform tests on lithium batteries to determine their ignition properties when subjected to external sources of mechanical energy, including acoustic energy in flight range modes and acoustic harmonic modes.

“The purpose of this testing is to determine the safe limits for the air carriage of lithium type batteries in dynamic aeroelastic, vibrating structures where the battery electrolyte composed of an organic solvent and dissolved lithium salt could become unstable when exposed to these forms of mechanical energy,” states the report.

Speaking after the release of the GCAA report, UPS pilot union chief Robert Travis said his members were already helping to develop new air cargo fire safety technology in the wake of the 2010 crash.

“Nearly three years following this tragic accident, UPS pilots welcome the release of this final report,” said Travis. “Some of the GCAA’s recommendations are already being addressed by a joint company and pilot union group, the IPA/UPS Safety Task Force, created shortly after the accident,” he stated.

Travis said the union has worked with UPS to design, build, test and demonstrate for the FAA and NTSB an active fire suppression system capable of suppressing and containing a fire for up to four hours.  The technologies incorporated in that container, known as the Unit Load Device, consist of improved materials and a potassium-based aerosol suppressant.

“We encourage the FAA and UPS to move quickly and deliberately in approving and fully implementing this new technology,” added Travis.

Prior to the release of the GCAA’s final report, the UPS/IPA Safety Task Force recommended other safety measures that are being implemented by UPS including EVAS (Emergency Vision Assurance System), and quick donning full-face oxygen masks for all UPS aircraft. Both provide significant improvements on the flight deck during an onboard smoke, fire or fume event.

“We tragically lost two of our best pilots in the Dubai crash. As UPS pilots, we are determined to do everything in our power to minimise the risk associated with on-board smoke and fire events,” said Travis. “This includes proper regulations governing the carriage of hazardous materials including lithium batteries.”

Posted in Airlines, CAAs/ANSPs, News, Safety

Comments are closed.