Boeing is one of the largest aircraft firms in the world and one of its most important recent projects for commercial aviation is the new 787 Dreamliner passenger jet. The 787 has had a rough time in testing and has seen significant delays due to advanced materials being used in the aircraft's construction and problems with suppliers.

The Seattle Times reports that yesterday one of the Boeing 787 test aircraft experienced a serious issue while flying. The aircraft reportedly had 30 to 40 people on board, who were apparently part of the flight test crew monitoring the aircraft's performance. The electrical fire in the aircraft resulted in the loss of primary flight displays and the aircraft's auto-throttle controls according to a source familiar with the incident that spoke to the Seattle Times.

Reports say that smoke was noted in the back of the cabin on the 787, which is Dreamliner number 2. The smoke was detected by a team of technicians that work at computer stations monitoring flight data while the aircraft was on approach to land in Laredo, Texas.

787 number 2 had been aloft for six hours and was on a mission to test the nitrogen-generation system of the aircraft that is designed to reduce the flammability of the fuel in the wings of the aircraft. The test flight was seeking hot weather to test the system, had taken off from Yuma, Arizona early Tuesday morning, and was originally headed to Harlingen, Texas. 

The pilots of the aircraft had decided to land in Laredo, Texas after weather conditions favorable to their tests were noted. According to reports, the backup electric power generating system called the Ram Air Turbine or RAT had deployed automatically. The RAT is designed to provide enough power in case of an electrical system failure allowing the flight controls to operate.

In addition to the flight controls and the flight displays, virtual all major systems of the 787 are electrically controlled including the hydraulic pumps that manipulate the flight-control surfaces, the brakes, cabin pressurization, engine-starting system and wing ice-protection system.

The pilots of the 787 were already on approach to land when they were forced to declare an emergency. Once the aircraft landed, the emergency slides were deployed and the aircraft was evacuated on the runway.

An FAA spokesperson said, "The aircraft landed at Laredo at about 2:54 Central Time. The aircraft was evacuated on the runway. They pulled the slides." A person familiar with the incident said, "If this had happened at 25,000 feet, we might be talking about something much more serious."

Whether or not this will delay the flight testing of the 787 depends on the cause of the incident. If it requires a redesign, delays are expected. If a faulty part caused the issue that can be replaced, testing should resume shortly. Boeing and the FAA are investigating the accident now.

Despite the long running delays, the Boeing still has 847 firm orders for the 787 (that number takes into account some of the units that were cancelled after the significant delays the program has faced). One of the key improvements that Boeing has worked into the 787 is that most of the systems of the aircraft are electrically controlled rather than using pneumatic systems. 

The move to electrical control from the pneumatic system was made by Boeing to reduce the complexity of the aircraft.

The first test flight for the 787 was in December 2009 and the fifth prototype 787 took its maiden flight in July 2010.