Fire Risk

Pilots’ growing dependence on tablet devices that replace heavy flight manuals in the cockpit is simply adding to the severe fire risk that lithium-ion battery technology poses, according to an expert aviation safety group.

In a report released earlier this summer, the UK’s Royal Aeronautical Society said passengers flying on a typical single aisle jet could be bringing more than 500 potentially lethal batteries on board to power personal gadgets – and the devices that pilots are increasingly using to plan their journeys could be potentially just as dangerous – if not more so.

Electronic flight bags or EFBs are gaining use in all forms in aviation and in the cockpit are used to replace flight deck documentation. Because the more portable type of these devices – essentially those that can be bought off-the-shelf – are not subject to the usual airworthiness checks, the report warns that they pose much more of a potential hazard – in so much as any failure of the lithium-ion technology on which they rely will occur in the cockpit.

The report cites the US Federal Aviation Administration (FAA) Technical Center which last year conducted research on all classes of EFBs and cited the primary concern as ‘thermal runaway’ of lithium batteries.

“The primary concern is the resulting fire/smoke hazards should one of the lithium-ion batteries installed in these units fail and experience thermal runaway, a failure causing rapid increases in temperature, significant smoke production and at times, explosion and/or rocketing of the battery cell,” it stated.

In one test, a battery failed so dramatically that at one point it blasted open an unlatched cockpit door.

“The most striking safety hazard, however, was the volume and density of smoke that emanated from the failed battery cells,” the FAA reported.

During one test in which only four of the nine battery cells went into thermal runaway, an installed smoke meter registered a severe lack of visibility within the flight deck, something that would effectively disable the pilots.

The report cites one expert as warning that as portable electronic devices become more powerful, so will battery technology. Not only will the increasing energy densities of the batteries increase the likelihood of producing an uncontrollable in-flight fire but the proliferation of portable electronic devices itself will further increase the risk of battery failure incidents.

The report documents how an in-flight battery fire occurred last April on a flight from Toronto to Minneapolis when at 28,000ft, the battery from a passenger’s air purifier device caught fire.

A cabin crew member wet paper towels to put out the fire before submerging the smouldering battery in a cup of water. On the flight deck, meanwhile, the captain, smelling a very strong burning electrical odour, declared an emergency and diverted to Michigan.

Although combusting battery incidents are not cited as the cause, one study revealed that during a 36-month period between 2002-2004, there were on average two and a half smoke events each day somewhere in the world with Boeing and Airbus aircraft affected roughly equally.

Speaking at a Royal Aeronautical presentation on smoke, fire and fumes in transport aircraft last month, Captain John Cox, CEO, Safety Operating Systems, said a statistical analysis of commercial jet aircraft accident data shows that in-flight fire was responsible for the fourth highest number of on-board fatalities and was the seventh most frequent cause of accidents in 2005 (Boeing, 2005).

Using the CAST taxonomy, the number of fatalities is a primary criterion. Since 2005 there have been two B747 freighter fires that resulted in the loss of the aircraft and flight crews, but no fatal fires aboard passenger aircraft.

Consequently, the ranking of in-flight fires has decreased since 2005 due to the reduction in passenger fatalities in the annual Boeing statistical summaries. Had the freighter fires occurred in passenger aircraft causing fatalities the rankings would certainly have been different.

Read More:
GCAA: 747 vibration risk to lithium-ion cargo?
FAA set to relax rules on personal gadgets

Posted in Airlines, CAAs/ANSPs, Features, Safety

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