"Product Review: Visual Instruments Flap Position Indicator
STC SA00819SE
By Charles Lloyd
The Problem
Cessna single-engine aircraft flap systems changed from a manual to an electrical design in the 1960s. Bill, a 1966 Cessna 182J and his pilot endured life with the curse of this design until installing the Visual Instruments Flap Position Indicator STC.
The original Cessna system is a look-at-it-until-you-get-it-right-type workload. You hold the switch down until the flap indicator shows the flap angle that you hope is close to your desired setting. The first problem is that the flap indicator accuracy is plus or minus 10 degrees. Second, the indicator is in the lower right panel and the pointer is hard to see. With this challenge, two “tribal knowledge” flap-setting methods are: 1. The “one potato two potato” method where you count two potatoes for each five degrees of flap setting desired, and 2., lower the flaps until you feel a slight vibration and viola! you have oh, about a 30-degree flap setting.
The Solution
Visual Instruments Flap Position Indicator, STC SA00819SE, is a high quality, workload-reduction solution to this problem. A Light Emitting Diode (LED) bar graph display replaces the original pointer indicator in the instrument panel and a precision quality position transmitter mounted in the wing replaces the original Cessna unit.
The LED is a nine-element vertical bar graph display. The top five are green elements and then four amber elements. The first green element at the top of the display lights when the master switch is on. Then another LED illuminates for each five degrees of flap travel. Flap indications through 20 degrees are green LEDs, five green LED will now show in the indicator. The final four LEDs indicating 25-40 degrees are amber. An auto dimmer circuit controls LED brightness to a comfortable level for day and night operation.
Documentation
Wow, a seven-page installation document that is easy to read and covers everything you need to know about installing flap indicator components! Section "a" describes the two components. The indicator and transmitter are essentially direct replacements for the original components.
Section “b” discusses installation and rigging. This section combined with two drawings and wiring diagrams for both single and two wire systems make the installation an easy to follow process. Remove the old transmitter. Crimp on the proper supplied connector and then install the Visual Instruments Transmitter on the original bracket and connect to the flaps. Then, remove the old position indicator and install the new nine-element LED indicator.
Rigging is a two-step process. Set the flaps to ten degrees and adjust the flap position transmitter to show three green LEDs. Tighten the adjustment screws and then lower the flaps to 40 degrees and adjust the bias screw in the LED indicator to show nine LED elements. Close up the access panels, and you are done with the mechanical work.
The Instructions for Continued Airworthiness, Troubleshooting and Flight Manual Supplements are all there. The icing on the cake is a Form 337 with the backside already completed. All your A&P/IA needs to do is fill out the front with your ownership, aircraft information, sign the Form 337, make your logbook entry and you are done.
Installation
Installing this $399 system is an easy four-hour project. Following the old saying, “Measure twice and cut once.” means taking to time read the installation instructions, then open up the aircraft and look at how you are going to remove the old and install the new components. This step takes approximately 30 minutes.
The flap position transmitter installation is more involved with removal, connector crimping and installation. This process requires an hour or less.
The LED Position Indicator is straightforward. The instrument panel location is accessible and is a thirty-minute job. However, the hole in Bill’s Avion Research panel did not match the shape of the new indicator. Using a small file and removing a bit here and then a bit there required another thirty minutes effort to do the work correctly.
Expect thirty minutes for rigging and logbook entries and Form 337 completion and you have a finished installation.
Operation
The cockpit workload reduction is dramatic. The “one potato two potato” count vanishes from flap selection. All you need to do is hold the flap switch down, glance at the LED bar and you know flap setting instantly and accurately. The Visual Instruments flap transmitter is accurate and you no longer have to set the flap and look out the window to confirm what setting you have.
The only question I ask myself is why I did not install the STC on Bill earlier. The Visual Instruments Flap Position Indicator is proof that there is always room for a better mousetrap."
Cessna Flyer
