Flap Position Indicator

The Cessna system employed a sending unit that was not hermetically sealed, causing the electrical wire windings of the rheostat to become corroded. This happens especially fast if you keep your aircraft in a wet climate. The corrosion is accelerated by Electrolyses, as the windings are electrically energized whenever the master is turned on.

The Visual Instruments Indicator employs a high quality sealed potentiometer in its sender. The potentiometer is rated to 40,000 ft.  It uses low-level electronic signals to communicate with the display, so the higher currents employed by the older style gauges are not necessary.

The Cessna unit uses a thin wire rod to connect the sender transmitter to the flap pulley. This wire is easily bent and is difficult to adjust. It is the source of many reading errors.

The Visual Instruments Indicator Design is quite clever.  It uses a solid aluminum follower arm, which is connected to the flap pulley. The arm is allowed to rotate on the shaft of the potentiometer making the adjustment process simple. Three screws are tightened to secure the position permanently.

Cessna’s flap position indicator systems were made by AC Spark and then by Stewart-Warner until these companies went out of business several decades ago. Since then these systems have been made by Rochester Instrument Co. THE ORIGINAL GAUGES AND SENDER UNITS MADE BY AC SPARK & STEWART-WARNER ARE NOT COMPATIBLE WITH THE ROCHESTER GAUGES AND SENDER UNITS. THUS, IF YOU OWN ONE OF THESE OLDER COMPONENTS AND IT GOES OUT, YOU THEN HAVE TO PURCHASE BOTH THE FLAP INDICATOR DISPLAY GUAGE AND THE SENDING UNIT AT A SALES PRICE FROM CESSNA OF APPROXIMATELY $1,800.00, AND CURRENTLY THERE HAS BEEN A 12-WEEK TO 6- MONTHS WAIT TIME.

The good news is that you can purchase the Visual Instruments Flap Position Indicator System for less than the factory replacement system, it will have a 1-year warranty (much longer than Cessna’s warranty), our system is much more modern with an LED light bar graph & self-dimming capabilities.

The Cessna gauge is not linear. (The readings at ends of the scale are bunched up.) This is because the sender is connected to the rotating flap pulley, which moves in a sinusoidal motion.

The Visual Instruments Indicator corrects for this error in its electronic circuits. Flap position   is displayed on a linear bar graph. The Display has a much higher resolution (5-degrees) for each bar as opposed to 10-degree markings on the Cessna indicator.  It is very similar to the way commercial jets display their flap position on their Glass Cockpit Displays.

On many model Cessna’s the flap indicator is located way off on the right side of the instrument panel. This creates parallax errors and difficulties reading the indicator. At night, the gauge is not internally lit, making readings even more difficult.

Because of its LED display, the Visual Instruments Indicator is not subject to parallax errors. It has an incredibly wide viewing angle so the pilot will have no trouble reading it in the daylight or at night. Its color-coded display makes it easy to identify the 10-degree position for an emergency go-around procedure. The Indicator is equipped with an internal light sensor that adjusts the display to the proper brightness automatically.