The reason is "technology obsolescence," says Chuck Royalty
, lead engineer for network systems with Boeing's
777 program.The 100-megabits/sec (Mbits/sec) optical system links maintenance terminals with the central maintenance function in the Aircraft Information Management System (AIMS).The original maintenance network also included links using 10-Mbit/sec Ethernet.
For a system that uses glass fiber and electromechanical components in a severe environment, the B777's FDDI has a reputation for reliability."I am aware of maybe one [optical fiber] break because a cable was bent," Royalty
, a longtime FDDI user, considers the bus "very reliable in service."
But now the technology is becoming more expensive and less available, Royalty
says.Boeing plans to replace the optical system with 10-Mbit/s, copper Ethernet, concurrent with its implementation of an AIMS-2 upgrade on the B777-300ER and 777-200LR airplanes, expected in the third quarter of 2003 and the first quarter of 2004, respectively."Instead of being part FDDI and part Ethernet, the maintenance network will now be all-Ethernet," Royalty
predicts that the replacement, all-Ethernet system will be "a wash"–comparable in maintainability and reliability to the optical system.
Civil aviation appears to be moving toward faster Ethernet technology.Boeing
already employs a 10-Mbits/sec Ethernet network on the 767-400ER aircraft for flight-critical displays.And Airbus plans to deploy a 10-Mbits/sec/100-Mbits/sec, full-duplex, switched Ethernet communications system on the A380 super jumbo aircraft.ARINC's Ethernet standardization effort can be found in Project Paper 664, including both 10 Base-T and 100 Base-T implementations.No date has been set for the completion of that work.