TWIN COMANCHE C/R
INSTRUMENT PANEL
The instrument panel is designed to accommodate the customary advanced flight instruments on the
left side in front of the pilot and engine instruments on the right side. The optional instruments such as the
gyro instruments of the flight group are shock mounted. The Artificial Horizon and Directional Gyro in this
group are operated by an optional vacuum pump on each engine. The vacuum system standby is the
optional, electrically operated Rate of Turn indicator.
INSTRUMENT STATIC PRESSURE SYSTEM
Static air for the airspeed indicator, altimeter and vertical speed indicator is supplied from two static
ports, one located on each side of the aft fuselage section.
An optional, alternate static source is available to provide continuous operation of the pitot static
instruments should the static system ports or lines become obstructed. The alternate static source is located
in the cabin on the lower left side of the control quadrant.
If incorrect instrument readings are suspected the alternate static source valve should be opened,
venting the static system to cabin pressure. Cabin pressure will vary, however with cabin ventilators open,
cabin heater operating and various airspeeds.
Use of the alternate static source may result in the following instrument indications: The altimeter
reads higher than normal; indicated airspeed greater than normal; and the vertical velocity indicator
momentarily shows a climb.
The following table shows airspeed corrections for the standard static system and the alternate static
system:
IAS
MPH
80
88
120
160
200
220
80
91
100
120
Standard
Alternate
Static System
Static System
CAS CAS
MPH MPH
82
81
90
91
121
113
160 148
197
185
216 204
80 81
90
91
98
97
117
113
Gear and
Flaps
Retracted
Extended
PAGE
10
AIRPLANE
AND SYSTEMS
ISSUED:
June 1,197O
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