Fadec Engines On B767
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Joined: May 2002
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From: Australia
Fadec Engines On B767
A discussion point with a fellow pilot mate of mine on the B767 we operate has Fadec engines CF6'S.
What is the relationship between the Fadec computer and the EEC?
Is the Fadec computer used only predominantely during the start cycle or does it talk to the EEC computer or the TMC if the EEC has failed. Any around about answers would be appreciated.
What is the relationship between the Fadec computer and the EEC?
Is the Fadec computer used only predominantely during the start cycle or does it talk to the EEC computer or the TMC if the EEC has failed. Any around about answers would be appreciated.
Joined: Oct 1999
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From: United Kingdom
So how come non-FADEC 767s have EEC?
Edited to answer my own question.
Non FADEC engines have an EEC mounted on the HMU. These engines can be operated by conventional HMU control by disengaging the EEC.
FADEC engines have a dual channel full authortiy FADEC with no hydromechanical backup.
Edited to answer my own question.
Non FADEC engines have an EEC mounted on the HMU. These engines can be operated by conventional HMU control by disengaging the EEC.
FADEC engines have a dual channel full authortiy FADEC with no hydromechanical backup.
Last edited by Bally Heck; 12th June 2002 at 14:00.
Joined: Jul 2001
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From: Lisbon - Portugal
I would like to develop Bally Heck answer.
The EEC (non FADEC) is called a supervisory control system and contains all elements of conventional hydromechanical control plus an engine electronic control. Boeing required the system to be designed so that failures in the electronic portions are passive and result in no thrust change. In this event the hydromechanical control then assumes complete governing of the engine. The hydromechanical element govern basic engine operation (starting, accell, decel, speed governing, vane and bleed scheduling). The electronic control provides precision thrust management, rotor speeds limit protection and transmission of information for cockpit displays.
The supervisory control systems were certified on B767 with JT9D-R4 and CF6-80A engines in 1982. At that time Boeing judged that overall control system design and reliability had not yet been established to the point where a full authority digital engine control (FADEC) could be pursued for the initial 767 airplane. The 767 with PW4000,CF6-80C,RB211-524H FADEC controled engines were certified in 1988/1989.
The FADEC control doesn't employ any hydromechanical computations except for a mechanical overspeed governor. The control performs the following functions: starting, accell, deccel, speed governing, vane and bleed scheduling, engine operating and rating data; fault detection, isolation and acomodation by each of the two EEC channels and indication of fault status for display and maintenance. Flight crew commands required to control the engine are input to the EEC.
Mechanical thrust cable systems are not required with FADEC controllers.
The autothrottle computer (TMC) provides a trim command data word to each FADEC controller on the digital data buses between the units. Each FADEC controller reads it's own trim word and implements the requested change in power setting. The A/T computer adjusts the word, as necessary, to achieve equal thrust on all engines. The FADEC controller limits the magnitude of the received trim word so that a failure of the A/T computer can not cause a significant thrusth change on the engines.
Regards
The EEC (non FADEC) is called a supervisory control system and contains all elements of conventional hydromechanical control plus an engine electronic control. Boeing required the system to be designed so that failures in the electronic portions are passive and result in no thrust change. In this event the hydromechanical control then assumes complete governing of the engine. The hydromechanical element govern basic engine operation (starting, accell, decel, speed governing, vane and bleed scheduling). The electronic control provides precision thrust management, rotor speeds limit protection and transmission of information for cockpit displays.
The supervisory control systems were certified on B767 with JT9D-R4 and CF6-80A engines in 1982. At that time Boeing judged that overall control system design and reliability had not yet been established to the point where a full authority digital engine control (FADEC) could be pursued for the initial 767 airplane. The 767 with PW4000,CF6-80C,RB211-524H FADEC controled engines were certified in 1988/1989.
The FADEC control doesn't employ any hydromechanical computations except for a mechanical overspeed governor. The control performs the following functions: starting, accell, deccel, speed governing, vane and bleed scheduling, engine operating and rating data; fault detection, isolation and acomodation by each of the two EEC channels and indication of fault status for display and maintenance. Flight crew commands required to control the engine are input to the EEC.
Mechanical thrust cable systems are not required with FADEC controllers.
The autothrottle computer (TMC) provides a trim command data word to each FADEC controller on the digital data buses between the units. Each FADEC controller reads it's own trim word and implements the requested change in power setting. The A/T computer adjusts the word, as necessary, to achieve equal thrust on all engines. The FADEC controller limits the magnitude of the received trim word so that a failure of the A/T computer can not cause a significant thrusth change on the engines.
Regards
Joined: Jul 2000
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From: West
There are 3 types of engines used on the 767s I'm flying these days...the PW4060, the GE CF-6-80C non-FADEC, and the GE CF-6-80C FADEC. I notice that the PW engines like to synch the EPRs. The problem with this is that often the N1s will be off by typically .5%. This is noticeable in the mid cabin. I have even seen one pair that were off 1.0%, but one of these engines had 2 fan exit guide vanes removed for maintenance, and I attributed the difference to this fact.
The GE engines match N1s and are not a problem. I believe we are now standardizing on the GE engines, which is very nice because the PWs take forever to start. Why do they take so long to start compared to the GEs?
The GE engines match N1s and are not a problem. I believe we are now standardizing on the GE engines, which is very nice because the PWs take forever to start. Why do they take so long to start compared to the GEs?
Joined: Oct 2001
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From: The Beautiful South
Don't know about the PW4000 series......... only know how bad the JT9 s were....... (Oil drinkers)
The RB211-524G/H are not full FADEC engines........ They have a FAFC, which is Full Authority Fuel Control.....Bleed Valves and VIGVs are still mechanical control.
The RB211-524G/H are not full FADEC engines........ They have a FAFC, which is Full Authority Fuel Control.....Bleed Valves and VIGVs are still mechanical control.
