WES -SPEED TAPE PARAMETER CALCULATION -1
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WES -SPEED TAPE PARAMETER CALCULATION -2
Speed Tape Parameters
The WEUs calculate these speed tape parameters:
*
Maximum operating speed and the maximum operating mach number (VMO/MMO)
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Maximum flaps extended/maximum gear extended speed (VFE/VLE)
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Maximum speed (VMAX)
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Minimum speed (VMIN)
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Maneuver margin above stick shaker speed (VSSNG).
Inputs
The air data inertial reference unit (ADIRU) supplies these inputs for speed tape parameter calculation:
*
Corrected angle of attack (AOA)
*
Barometric altitude
*
Body longitudinal acceleration (AL)
*
Body normal acceleration (AN)
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Computed airspeed (VCAS)
*
Mach number (MACH NO)
*
Static pressure.
If the ADIRU fails, the secondary attitude air data reference unit (SAARU) supplies the same inputs.
The primary flight computers (PFCs) supply the PFCS in secondary or direct mode of operation signal, and speedbrake lever position (SBLP).
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The proximity switch electronic units (PSEU) supply these inputs:
*
All gear up and locked
*
Nose gear down and locked
*
Nose gear not compressed.
The flap slat electronic units (FSEUs) supply flap and slat position.
The alternate gear down dispatch switch supplies three identical ground signals when the switch is in the VMO position. When the alternate gear down dispatch switch is in the VMO position, the WEUs send a memo message request to the AIMS cabinets. The primary display function of the AIMS shows the memo message VMO GEAR DOWN.
Speed Tape
The primary flight display (PFD) shows the speed tape. The maximum speed (VMAX) and minimum speed (VMIN) show on the speed tape.
VMO/MMO Logic
The VMO/MMO logic calculates the maximum operating speed (VMO) and the maximum operating mach number (MMO).
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The VMO and MMO are normally 330 knots and mach .87. When at least two of the three ground signals from the alternate gear down dispatch switch show the switch is in the VMO position, the VMO/MMO logic changes the VMO and MMO to 270 knots and mach .73.
The VMO/MMO goes to the maximum operating speed (VMAX) logic. When the computed airspeed (VCAS) or the mach number (MACH NO) is more than the limit calculated by the VMO/MMO logic, the VMO/MMO logic makes an overspeed warning.
VFE/VLE Logic
The VFE/VLE logic calculates VFE/VLE.
When the flaps and slats are up and the gear not clean signal is false, VFE/VLE is no computed data. When the flaps are not up, VFE/VLE is the same as VFE. When the flaps are up and the gear not clean signal is true, VFE/VLE is the same as VLE.
VFE/VLE goes to the VMAX logic. VFE/VLE also goes to the AIMS cabinets for FMCF calculations.
VMAX Logic
The VMAX logic calculates the VMAX. If the wing is clean and the gear not clean signal is false, VMAX is the same as the VMO/MMO. VMAX is the same as VFE/VLE for any other condition.
VMAX goes to the AIMS cabinets for display on the PFD and for FMCF calculations.
VSS Logic
The stick shaker speed (VSS) logic calculates VSS. VSS goes to the VMIN logic.
VMIN Logic
The VMIN logic calculates VMIN. VMIN is the same as VSS.
VMIN goes to the AIMS cabinets for display on the PFD and for FMCF calculations.
VSSNG Logic
The VSSNG logic calculates VSSNG. VSSNG goes the AIMS cabinets for FMCF calculations.
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WES -SPEED TAPE PARAMETER CALCULATION -2
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WES -AUTO SLAT ENABLE
General HYDIM Interfaces
The auto slat enable function extends the leading edge slats automatically when the airplane is near a stall. The slats extend from the sealed position to the gapped position. This action gives more lift. Channels L1 and R1 auto slat enable signals go to HYDIM HC2. Channels L2 and R2 auto slat enable signals go to HYDIM HC1.
The auto slat enable function only operates when the flaps are 1 to 20 units, and the airplane is in the air. Operation
If the corrected angle of attack (AOA) is more than the auto slat trip point (AOA AS), the WEUs make an auto slat enable signal.
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