Boeing’s entire fleet of six 787 flight-test aircraft remains grounded as the company investigates the cause of an electrical fire that broke out in the second airplane, ZA002, during a November 9 test flight. The company has determined that a failure in a power control panel, known as the P100 panel, led to a fire involving an insulation blanket and a loss of the airplane’s primary electrical system as it approached Laredo, Texas. Backup systems, including the deployment of the ram air turbine (RAT), functioned as expected and allowed the crew to complete a safe landing. The 42 Boeing crewmembers and support personnel on board used emergency slides to evacuate after the airplane landed in Laredo.

Boeing has removed the P100 panel and shipped a replacement unit to Laredo. It has also removed the insulation material near the unit for inspection. One of several power panels in the aft electronics bay, the P100 panel receives power from the left engine and distributes it to an array of systems. Although the company said investigators found molten metal near the P100 panel, the presence of the material “is not unexpected in the presence of high heat” and “does not reveal anything meaningful to the investigation.” 

According to Boeing, inspection of the surrounding area will take several days. “As part of our investigation, we will conduct a detailed inspection of the panel and insulation material to determine if they enhance our understanding of the incident,” it said. “We continue to evaluate data to understand this incident. At the same time, we are working through a repair plan. In addition, we are determining the appropriate steps required to return the rest of the flight-test fleet to flying status.”

The crew first noticed smoke as the airplane approached Laredo in normal flight conditions, according to a Boeing spokesperson. The airplane had flown for “several hours” since departing Yuma, Ariz., on a flight path that took it north, over North Dakota, then east, over Iowa, before heading south to Texas, while crewmembers evaluated the performance of its nitrogen generating system. Boeing said it has found no reason to suspect that the monitoring or earlier testing of the system had anything to do with the incident, however.

Now close to three years behind schedule, the 787 program can ill afford to encounter any further obstacles to certification. At last report Boeing expected to deliver the first production airplane to Japan’s All Nippon Airways in mid-February. It remains unclear whether or not this latest incident might jeopardize that schedule.  

“We cannot determine the impact of this event on the overall program schedule until we have worked our way through the data,” said Boeing. “Teams have been working through the night and will continue to work until analysis is complete and a path forward is determined.”