1) Redundancy: dual FADEC system "Following analog electronic control, the clear path was digital electronic control. Later in the 1970s NASA and Pratt and Whitney experimented with the first experimental FADEC, first flown on an F-111 fitted with a highly modified Pratt & Whitney TF30 left engine. The experiments led to Pratt & Whitney F100 and Pratt & Whitney PW2000 being the first military and civil engines respectively fitted with FADEC and later the Pratt & Whitney PW4000 as the first commercial "dual FADEC" engine. Safety: With the operation of the engines so heavily relying on automation, safety is a great concern. Redundancy is provided in the form of two or more, separate identical digital channels. Each channel may provide all engine functions without restriction. FADEC also monitors a variety of analog, digital and discrete data coming from the engine subsystems and related aircraft systems, providing for fault tolerant engine control." Source and further information: http://en.wikipedia.org/wiki/FADEC "There are some pictures of the dual FADEC system" " I checked everything: FADEC1, FADEC2, fuel pumps, instruments, starter relay, NAV lights, strobe, ACIS... everything works without smoke!" Source and further information: http://users.telenet.be/helicopter/project.html 2) Generation difference (here not the case): "Hi guys I am looking for someone who cal clear a few doubts I have concerning the relationship between the FADEC and the EEC. " "i think it is a problem of what a fadec and what an eec is....the electronic engine control (EEC) is the "earlier" version of the Full authority digital engine control (FADEC). It is also a question of what the engine manufacturers call them.....But the engine world has more or less accepted that the EEC is the earlier FADEC.....you can find EEC´s on f.ex. PW4060....and the FADEC on CFM 56-5C´s. Then you have diferent generations of FADEC´s...F. ex. the CFM 56-5A (A320) was the first CFM engine to have a FADEC, hence it was called a FADEC1, the CFM56-5C (A340) has a FADEC2. I know it is confusing.....it is also some times for us in the business......But i can give you an example....for. ex. a FADEC engine can make a complete valve actuator check (f. ex. IGV´s, VBV´s, BSV´s, and TBV´s....all bleed valves that prevent stalls/surges).....to make the hole thing more confusing, you can even have different names from both engine manufacturer, and airplane manufacturer......eg Boeing will call it a EEC and engine manufacturer a FADEC......don´t worry..all you need to know is that it is a electronic box that replaces the good old mechanical Fuel control unit.....hope it helped....as i said a lot of different names for the same thing in this business." Source and further information: http://www.airliners.net/aviation-forums/tech_ops/read.main/24669/ 3) two motors: "each engine M1, M2 includes a respective controlling electronic computer FADEC1, FADEC2 respectively controlling the fuel metering unit D of the engine M1, M2 to which it is connected" Source and further information: "balancing the power of two turboshaft engines of an aircraft" http://www.faqs.org/patents/app/20080275597

Thx :) that gave me much info ;)