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Learjet Spoileron System Troubleshooting

December 2009

I field a lot of questions in regards to troubleshooting classic Learjet Spoileron systems. Following are the steps that I take to troubleshoot this area. It is a very simplified, but effective method.

Before beginning, jack the aircraft and have a hydraulic mule hooked up and in place. There is a hierarchy of components that I use to get started. Always verify the operation of the system in the following order. Each step must operate before moving on to the next mode.


There are very few components required for Ground Spoilers to deploy properly. They are the spoiler solenoid, the spoiler actuators and the switch in the pedestal. Use 28 VDC and 1500 PSI of hydraulics, up they should go!


Use the components listed in step one and add the Servo Valves on spoileron manifold and the spoiler follow-ups. 115 VAC is required. The Air Spoilers use the actual squat switches, not the squat switch relay panel. Pulling the squat switch C/B will not work for this mode of operation.


Part one

The 25º Flap switches that activate the Spoileron mode essentially create a jumper circuit external of the Spoileron computer. Drop the flaps and check for continuity. If there is continuity, proceed.

Part two

Now add the Aileron Follow-ups. Move each aileron independently and the spoiler board will go up with the on-side aileron. Add the 16º switches on each side. If either one opens, the Spoilerons will fail with an “Aug Ail” or “Spoiler Mon” annunciator, depending on model.

Keep in mind that this is a very simplistic method to get you started. Always refer to the applicable aircraft maintenance manual for the actual rigging and operational checks.

If you have questions about gust locks or other Learjet tech issues, contact your Duncan Aviation Learjet Tech Rep.