BUCS Flashcards
BUCS Description
Emergency fly-by-wire backup control system which permits continued controlled flight in the event of a jam or severance in mechanical controls.
ARDD
Automatic Roller Detent Device - provides means to physically disconnect crewstation from flight linkage
LVDT
Linear Variable Displacement Transducers - Translates control motion into an electrical signal that is utilized by the FMC to provide SAS, CAS, BUCS, and hold mode functions.
RVDT
Rotary Variable Displacement Transducers (RVDT) are used to sense a decoupling of the ARDDs
What is needed to operate BUCS?
The primary hydraulic system and the FMC must be operational for BUCS to operate.
Jammed control linkage
If a jam has occurred, the FMC will engage BUCS when one of the crewmembers disconnects the controls from the mechanical control linkage by decoupling via the ARDD.
Failure of the primary hydraulic system results in?
In the loss of all FMC SCAS (SAS, CAS, and BUCS).
How is BUCS controlled?
In the BUCS mode the mechanical controls are physically decoupled and control is now maintained through an electronic control loop consisting of the following components:
(a) FMC
(b) LVDT
(c) Electro-Hydraulic Valves
(d) Actuator Solenoids
Severance
Upon sensing a control mistrack the LVDT will send a signal to the FMC which will engage BUCS
Bucs on - severance aft
Bucs fail - severance between crew
BUCS FAIL (AXIS)
severance between crew stations.
Action: PLT TAKE CONTROL OF AIRCRAFT IMMEDIATELY
Or failed state
BUCS FAIL
FMC has determined that the BUCS is in a failed state and will not allow the system to activate.
Failed state
Or
Severance between
BUCS ON PLT (AXIS)
Severance aft of the crew stations
Action: EITHER CREWMEMBER CAN ASSUME AIRCRAFT CONTROL
BUCS ON (STATION)
Jam in one of the flight control axis’s
Action: CREWMEMBER WHO ROLLED THE ARDD HAS CONTROL IN THAT AXIS
Or severances aft
Bucs Fail (axis)
BUCS ON PLT (AXIS)
BUCS ON (STATION) (AXIS)
