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Debonair landing gear

Hi. I'm trying to understand the gear retraction system. Can anyone explain how the microswitch (weight on right main wheel) works in preventing inadvertent gear retraction on the ground? Doe it open or close a circuit? Where does it go to (gear computer somewhere on the airplane?). How do I know if it works (without commanding a gear up on the ground and hoping for the best). Is there a way to test it?
Sorry for the basic question. Thanks!

Model: Debonair 35-B33
Posted 3/11/2023 - 2 months ago

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These are all good questions. The answers are based on an un-modified 35B33.

The squat switch is actually a dual switch, one normally open circuit and one normally closed. 'Normally' refers to its un-actuated state, which in this case is when it is on the ground (not compressed). There are multiple circuits running through / actuated by the landing gear reversing switch (the instrument panel retraction switch). One is a low current circuit that goes to the normally closed circuit of the squat switch so when gear is selected up on the ground, the squat switch supplies current to the gear horn to tell you don't do that. The reversing switch also sends a higher current to the normally open set of contacts that is the main power wire for the motor to raise the landing gear: On the ground that set of contacts is open, no current flow to the motor, but in the air, the contacts are closed, and gear goes up. In the air, the normally closed circuit is open, that is why no gear horn actuation by the squat switch.

No computer, just a series of mechanical switches that need certain conditions to perform certain functions.

This switch is a check-list item for your annual inspection. If your IA is doing their job correctly, it is checked at least once a year.

Note there is a separate /independent circuit to operate the gear horn in flight under similar series-set conditions when gear is retracted and power from the engine is low.

ABS Tech Advisor

Posted 3/11/2023 - 2 months ago
Approved by Bob Ripley


Lets give you a reason to go flying. Let me assume that your B33 is airborne. Should you want to check you landing gear switches to see if they are working properly.

So, I would climb to about 5000 AGL (to give you enough room to recover if something goes wrong.)

Then slow down. Put the flaps down and then when you are in slow flight (with the landing gear retracted), pull the throttle all the way out. Soon you should hear a noisy sound. Then push the throttle in about an inch. The noise should cease. Now you know that your throttle's gear warning is working.

Then put the gear down. Repeat your closing the throttle. With the gear down and the throttle closed you should not hear any gear warning horn noise.

Now the only thing remaining is to confirm that your squat switch is working properly. The only way i can think of is to elevate your plane on jacks. Your throttle warning horn will go off. Now disconnect the rod between the squat switch and the landing gear. Now when you try to operate the landing gear, nothing will happen if switch is pushed down. IF the switch is up, then you gear should to retract (you do not have to fully retract the gear. Just pull the CB to stop the gear from moving. Then put the gear switch down and push in the CB.

When I am playing with the gear while on the ground I use the Circuit Breaker to avoid sudden reversal of the gear.

So, now i have given you a good excuse to go fly.

Oh, while you are airborne become comfortable with slow flight. In my experience I see too many people being afraid to fly their plane slow. They occasionally run off the far end of a runway because their landing speed is too highT.

You will find that your B33 is very capable of making a landing and exiting a runway within 1500 feet.

Have fun.


Posted 3/12/2023 - 2 months ago

Debonair landing gear