Gyro Suction and Pneumatic Pressure Guages
The Gyro Suction and Pneumatic Pressure Gauges indicate their normal ranges with green arcs.
Oxygen Pressure Gauge
The Oxygen gauge displays current oxygen pressure in PSI. This reading will normally change with altitude, and duration charts are available in the POH/AFM.
Alternate Static Switch
The Pilot's Alternate Static Source switch allows the pilot-side pitot-static instruments to utilize an alternate static source in the event of icing or blockage of the normal static source. Correction charts are available in the POH/AFM for when the alternate static source is in use. No alternate static source is provided for the copilot's flight instruments.
Copilot Side Panel Breakers
Many C90s have additional circuit breakers installed on the copilot's side panel.