The most common complaint we hear from customers who have purchased a Bendix/King radar sensor (RS-811A, RS-181A, RS-841A, RS-861A) is:
“This unit causes a constant ‘stab off’ condition. Pushing the stabilization switch on and off has no effect.”
However receiving a warranty unit as a replacement may not automatically fix this squawk.
In most cases the root cause of this squawk is when the radar sensor is installed the very first time and the 400 Hz reference adjustment has not been aligned in the aircraft. When this adjustment is outside of its range it will trigger a constant stab off condition. And depending on the 400 Hz reference adjustment of another unit, installation of a warranty replacement unit may or may not fix the problem.
It is important to remember when installing a radar sensor for the first time to perform the stabilization alignment procedure. Once the adjustments are made within the unit, it not necessary to do them again.
If you are sending this unit in for repair, it is not necessary to repeat the adjustments if the unit is going back on the same aircraft. The problem shows up when installing a radar sensor for the first time.
We include a copy of the stabilization alignment procedure with the 8130 of all Duncan overhauled units.
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