The US National Transportation Safety Board (NTSB) is conducting an urgent new round of testing on the Boeing 787's lithium-ion batteries in hopes of finding a root cause before most airlines resume routine commercial flights next month.

A solicitation issued on 3 May by the NSTB uses the "urgency" of the tests to justify bypassing federal regulations that require calling for multiple bids and instead award the work to a contractor based close to the agency's headquarters in Washington DC.

The computed tomography (CT) scans of eight lithium-ion battery cells "must also be completed within the shortest timeframe possible to provide the fastest possible receipt of this information to avoid potential future accidents involving this type of aircraft battery", the NTSB says.

"Since the [Federal Aviation Administration] has recently approved a plan intended to result in the Boeing 787 being approved for a return to service, the information from these tests is needed as soon as possible," the agency adds.

The selected contractor, Chesapeake Defense Services, was to begin CT scans of eight battery cells on 6 May, according to the solicitation. There are eight lithium ion cells in each of the 787's main and auxiliary power unit batteries.

More CT scans are also required on up to 40 additional battery cells, but in two parts. The first part will scan the batteries before a round of usage testing to establish a baseline configuration. A second round of CT scans to examine the batteries after the usage testing.

The FAA lifted the grounding order on the 787 fleet on 26 April three months after two lithium batteries over-heated on separate aircraft in early January. Ethiopian Airlines boarded a load of passengers on a single 787 flight on 27 April from Nairobi to Addis Ababa on 27 April and Qatar Airways has resumed its 787 services, but no other commercial flights involving the Dreamliner are expected to resume until June while airlines perform their own flight tests and re-train crews.

Though the NTSB and the Japan Transportation Safety Board (JSTB) continue to search for a route cause, Boeing has suggested that a triggering event for the battery failures may never be found.

Meanwhile, the company has improved the battery monitoring software, installed ceramic plates between each of the eight cells, replaced an aluminium battery enclosure with a stainless steel case and added vents and ducts to exhaust any smoke or fumes directly offboard the aircraft.

Source: Air Transport Intelligence news