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Boeing Says Failed Generator Caused 787 Diversion
AWIN First Dec05, 2012
Guy Norris [email protected]
Los Angeles
Boeing says electrical system problems that caused the crew of a United Airlines 787 to divert to Louis Armstrong New Orleans International Airport on Dec. 4 were triggered by the failure of one of the aircraft’s six main electric generators.
Initial reports indicated apparent issues with the aircraft’s sophisticated electrical system were flagged with on the engine indication and crew alerting system not long after the aircraft departed Houston for Newark around 8 a.m. The crew elected to divert to New Orleans after informing controllers at Houston Center that the aircraft had suffered an “electric malfunction.”
The aircraft, operating United flight 1146 with 174 passengers and 10 crew on board, landed without incident at 9:25 am.
Although reports from New Orleans suggest the crew suspected the aft electrical and electronics (E/E) bay as the source of the problem, program officials say inspections made after landing revealed no signs or fire or arcing.
This would mean the problem is not related to the in-flight fire in the aft E/E bay on test aircraft ZA002 in November 2010. That incident was traced to contamination by an unknown foreign object in the P100 power distribution panel that triggered one of the most serious incidents in the 787’s certification program .
Investigators now tell Aviation Week one of the aircraft ’s six starter-generators which form the heart of the electrical system appears to be the cause of the problem . The 787 system incorporates two 250 kVA generators per engine, and two 225 kVA generators on the auxiliary power unit, all operating at 235 volts alternating current.
The generators are connected to the engine gearboxes and operate at a variable frequency (360 to 800 Hz). Boeing adds that the “multiple redundancies built into the 787 ensured that the airplane remained powered. The generator will be replaced, additional checks completed and the airplane returned to service. There is no firm estimate for when this is expected to be complete but should not take long.”
The 787 electrical system is more sophisticated than on any previous commercial airliner because it replaces conventional engine bleed air to electrically power engine start, pressurization and wing ice protection. It also replaces hydraulic power for stabilizer trim and wheel brakes while supplying the traditional electrically-powered systems. The system incorporates two E/ E bays , one forward and one aft, as well as several remote power distribution units.
Operators are also checking 787s for improperly installed fuel-line connectors after the FAA issued an airworthiness directive calling for immediate inspections. The directive, which follows a Boeing service bulletin issued on Nov. 25, comes after fuel leaks were discovered in the in-service fleet. Inspections are focused on fuel system connectors in the engine pylon and whether lockwire and other components are correctly installed.
Boeing Says Failed Generator Caused 787 Diversion
AWIN First Dec05, 2012
Guy Norris [email protected]
Los Angeles
Boeing says electrical system problems that caused the crew of a United Airlines 787 to divert to Louis Armstrong New Orleans International Airport on Dec. 4 were triggered by the failure of one of the aircraft’s six main electric generators.
Initial reports indicated apparent issues with the aircraft’s sophisticated electrical system were flagged with on the engine indication and crew alerting system not long after the aircraft departed Houston for Newark around 8 a.m. The crew elected to divert to New Orleans after informing controllers at Houston Center that the aircraft had suffered an “electric malfunction.”
The aircraft, operating United flight 1146 with 174 passengers and 10 crew on board, landed without incident at 9:25 am.
Although reports from New Orleans suggest the crew suspected the aft electrical and electronics (E/E) bay as the source of the problem, program officials say inspections made after landing revealed no signs or fire or arcing.
This would mean the problem is not related to the in-flight fire in the aft E/E bay on test aircraft ZA002 in November 2010. That incident was traced to contamination by an unknown foreign object in the P100 power distribution panel that triggered one of the most serious incidents in the 787’s certification program .
Investigators now tell Aviation Week one of the aircraft ’s six starter-generators which form the heart of the electrical system appears to be the cause of the problem . The 787 system incorporates two 250 kVA generators per engine, and two 225 kVA generators on the auxiliary power unit, all operating at 235 volts alternating current.
The generators are connected to the engine gearboxes and operate at a variable frequency (360 to 800 Hz). Boeing adds that the “multiple redundancies built into the 787 ensured that the airplane remained powered. The generator will be replaced, additional checks completed and the airplane returned to service. There is no firm estimate for when this is expected to be complete but should not take long.”
The 787 electrical system is more sophisticated than on any previous commercial airliner because it replaces conventional engine bleed air to electrically power engine start, pressurization and wing ice protection. It also replaces hydraulic power for stabilizer trim and wheel brakes while supplying the traditional electrically-powered systems. The system incorporates two E/ E bays , one forward and one aft, as well as several remote power distribution units.
Operators are also checking 787s for improperly installed fuel-line connectors after the FAA issued an airworthiness directive calling for immediate inspections. The directive, which follows a Boeing service bulletin issued on Nov. 25, comes after fuel leaks were discovered in the in-service fleet. Inspections are focused on fuel system connectors in the engine pylon and whether lockwire and other components are correctly installed.
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