Boeing 787 Dreamliner - Mark Wagner [51]
The “smart” electrical distribution system, for which Boeing was awarded a patent in December 2003, comprised a data communication network, power distribution panels, and the RPDUs themselves. Throughout the flight the RPDUs were designed to “read” load connectivity from the power distribution panel. This was programmed to memorize how much power particular systems required for each phase of the flight, which enabled the RPDU to directly control electrical power to individual loads.
Designed to have a maximum usable fuel volume of some 33,530 U.S. gallons, the 787-8 fuel system incorporates a sophisticated series of electrically driven pumps supplied by FR-HiTemp that operate at twice the voltage of previous commercial models. Goodrich provides the fuel quantity indicating system (FQIS), which senses the density and level of the fuel in wing and center tanks. Mark Wagner
The true brains of the 787 reside in dual common computing resource cabinets that together form the common computing system (CCS). Developed by the former Smiths Aerospace before its takeover by GE, the CCS often is described as the 787’s central nervous system. The cabinets host processing and power control modules, along with network switches. Application specific modules, provided by third parties specified by Boeing, are installed in the cabinets. A second element of CCS is Rockwell Collins’s common data network (CDN), a fiber-optic Ethernet that connects all the systems that communicate with the CCS and with each other. The CCS also includes remote data concentrators (RDCs) that concentrates analog and digital signals from the remote sensors and effectors and put them onto the network. Mark Wagner
While some of the 235 VAC electrical system was supplied from the aft E/E bay, the bulk came from the forward E/E bay and RPDUs. Power for many of the systems previously operated by pneumatics came from a ±270 VDC system, which fed several large-rated adjustable-speed motors. These controlled the cabin pressurization compressor motors, the ram air fan motors, the nitrogen-generation-system compressor used for fuel-tank inerting, and large hydraulic pump motors. The system was supplied by four auto-transformer-rectifier units that converted 235 VAC power to ±270 VDC. The electrical system also included two 115 VAC external power receptacles to keep the 787 powered up on the ground if the APU was not running. Another two 115 VAC external power receptacles aft also were provided for any maintenance activities that needed the large high-speed motors.
Given the unprecedented importance of the electrical system to the entire program, it was among the first to be put out to competition. Hamilton Sundstrand was named as the main winner, with responsibility for three of the four main work packages, including the electrical power generation and start system; the remote power distribution system; and, in partnership with Zodiac, the primary power distribution system. The remaining package, the power conversion system, was awarded to Thales.
Integrated into the Hamilton Sundstrand’s electrical power generation and start system were electrical load control units (ELCUs) developed by Zodiac Group member Intertechnique. The ELCUs optimized the load to suit the power demands, and were controlled by a software and hardware system that worked at predefined microsecond intervals using a concept called time-triggered protocol (TTP). Developed by Austria-based TTTech, this involved a continuous communication between all connected nodes via redundant data buses to ensure that overloads in the bus system were prevented even if several demands occurred at once.
Honeywell flight control software was tested on a leased American Airlines 777-200ER under the controls