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Astra Landing Gear "Squat" Switch: Double Discrepancies

September 2009

Recently, we had an Astra SPX at our Lincoln, Nebraska, location for a “C” Check. The customer had incoming discrepancies for the #1 & #2 Engine DEEC buffers filling up every flight. In addition, the thrust reversers weren’t deploying on touch down until about 80 knots.


At first glance, the connection between the two discrepancies isn't obvious. Both conditions were solved by installing new right and left main landing gear ground contact switches—also called "squat switches". When both left and right main landing gear contact switches were replaced and rigged, the discrepancies were solved during the post-maintenance flight.

The charts in the maintenance manual give the pin outs for the main (32-60-01) and nose (32-60-04) landing gear ground contact switches. There are no pin outs for the DEECs. In order to locate them, you will need to go to the Wiring Diagram Manual 32-30-13.

Please contact a Duncan Aviation Astra Tech Rep for more information.