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Regulators explore fibers as possible culprit in Boeing 787 problems

A Boeing 787 jet lands Thursday Feb. 7 2013 Paine Field Everett Wash. following flight from Texas. The Federal AviatiAdministratigave

A Boeing 787 jet lands Thursday, Feb. 7, 2013, at Paine Field in Everett, Wash., following a flight from Texas. The Federal Aviation Administration gave Boeing permission to relocate the plane, which was at Meacham Airport for painting when the planes were grounded last month by battery problems. Although the battery was being closely monitored, the flight was just to relocate the plane and the FAA is still considering a separate Boeing request for 787 test flights. (AP Photo/Elaine Thompson)

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Updated: March 14, 2013 6:26AM

Regulators looking into problems that led to the grounding of the full fleet of Boeing 787 aircraft are investigating whether small fiber formations, so-called “dentrites” in the plane’s lithium-ion batteries may have caused the batteries to fail.

“We are looking at whether dendrites may or may not have been a factor,” National Transportation Safety Board spokeswoman Kelly Nantel said in an email statement Tuesday.

The entire fleet of 50 Boeing 787s was grounded by regulators globally last month after a battery fire on board a Japan Airlines plane parked in Boston and after battery problems and smoke in the cockpit forced an emergency landing by an All Nippon Airways 787 in Japan, prompting investigations by the Federal Aviation Administration and the NTSB as well as regulators in Japan.

The NTSB is considering several potential causes for short circuiting that occurred in battery cell No. 6 of the Japan Airlines 787. Those potential causes include looking at the state of charge of each individual cell, and the method and delivery of that charge, as well as evidence of “contamination, electrode folds, wrinkles and pinches and the assembly of the cells and battery,” Nantel stated.

The board also is examining the total design of the battery, including the physical separation of the cells, their electrical interconnections, and their thermal isolation from each other, she added.

The new technologically advanced 787 is the first Boeing plane to use rechargeable lithium-ion batteries for its main electrical system. Such batteries are prone to overheating and have additional safeguards that were designed to prevent fires and contain a fire should one occur.

On Monday, Chicago-based Boeing said a crew of 13, including pilots and 11 flight test personnel, completed a round of monitoring tests of the main and APU batteries on board a 787 test airplane. The round of testing also included a flight on Saturday. Pilots reported the flights were uneventful.

The FAA last Thursday gave Boeing permission to conduct test flights. The primary purpose of the flights is to collect data about the battery and electrical system performance while the aircraft is airborne. Boeing has permission to conduct the flights over unpopulated areas and is subject to restrictions, including extensive pre-flight testing and inspections and in-flight monitoring to ensure safety.

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