V-Speeds can be selected by use of the menu pushbuttons located on the Multi-function Control
Display Units (MCDUs). The bugs are labeled 1 (V
1), R (VR), 2 (V2), E (VENR), (this airspeed is
automatically displayed whenever V
1, VR, or V2 is selected for display; VENR is permanently selected
to 160 knots), RF (V
REF), and AP (VAPP). In manual mode, the bugs are positioned on the right
outside edge of the airspeed tape. They consist of a horizontal T-shaped symbol with its respective
label positioned to the right of the symbol. All the takeoff set bugs will be removed from the display
when the airplane airspeed exceeds 190 knots and the landing speed bugs are removed upon
touchdown.
When the airspeed is below 40 knots and weight on wheels is indicated, V
1, VR, V2, and VENR are
displayed in the bottom portion of the airspeed tape in the form of a digital readout. The digital
readout of the set value is displayed along with the bug symbol and are labeled in ascending order,
starting with V
1. Upon power up, the digital readouts for the set bugs will be dashes. As the V speeds
are set, the digital readouts will follow the readout on the MFD (PFD menu) and set accordingly. The
digital readouts are removed from the display when the first V speed value comes into view on the
airspeed tape.
Standby altitude and airspeed are available, in case of main electrical system failure, from the
standby altimeter and the standby airspeed indicator, which are located in the standby flight display.
These indicators receive their data from a standby micro air data computer (MADC). The standby
MADC, powered by its own battery source, obtains its pneumatic data from the standby pitot-static
system and converts it to digital electrical outputs for the indicators.
OVERSPEED INDICATIONS
Below 8000 feet altitude the limiting airspeed (VMO) is 260 KIAS; between 8000 feet and 28,907 feet
the limiting airspeed is 305 KIAS. When one of these limits is exceeded, the airspeed indication in
the window to the left of the attitude display in the PFD will be changed to red and an amber
annunciation. Also, to the left of the attitude sphere, will announce MAX SPEED. A red indicator tape
is also presented on the inside of the airspeed scale. The thermometer extends from V
MO/MMO to
larger airspeeds on the tape and appears in the indication as the airspeed reaches into the range
near V
MO/MMO. When the limiting airspeed is exceeded the overspeed warning aural alert will sound,
and will continue to sound until the airspeed is reduced below the limit speed.
NOTE
The aural warning system consists of two separate units which receive input from
airplane anomalies of overspeed, autopilot off and altitude alert. The units will output
aural signals to both the headphones and speakers.
Cessna Citation XLS - Instrumentation & Avionics
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