Is it corrosion? Would a puff of Corrosion-X or ACF-50 every other month help with micro switch longevity?
Which ones? There are several.
Those are made by Crouzet in France – see here
They should not fail often. They are sealed microswitches so external lubrication won’t do much. I don’t like the way these switches are actuated – a small misalignment is going to damage the switch. So checking the alignment of the landing gear mechanism (on jacks) while operating the gear slowly manually, is essential.
I have had a problem recently that the arm that protrudes from the switch (see photo above) was ever so slightly bent and therefore the part of the gear that moved that arm did not reach it, giving me a faulty indication of the landing gear position. Carefully bending it back solved it, so you may want to look at that first..
I think in most TB20GT installations that arm is slightly bent – it has been thus adjusted to work correctly. There is no other adjustment.
It’s not a good design. Those switches “only” operate the landing gear indicator lights, but they should still be a more sturdy type.
The problem is that the “proper” ones cost about €300, which is about €2000 from an aircraft manufacturer like Socata, and everybody tell you that you have to buy them from Socata…
http://www.ebay.de/itm/Proximity-Sensor-induktiver-Naherungssensor-induktiver-Naherungsschalter-M8-/271581113333?pt=Sensoren_Regler&hash=item3f3b7eebf5
VicSorry,
I think in most TB20GT installations that arm is slightly bent – it has been thus adjusted to work correctly. There is no other adjustment.
What I meant to say was that it was bent somehow during operation of the aircraft, hard landing probably..
