RE: Tam Jets Gear Fail Safe
Yes Dave you are correct so belt and braces may be the way to go. That said I have always had complete success with Clippard units and the rare leakage problems I have had have been internal cylinder seals in the retraction pistons which would be handled by my system.
Now you have raised the issue (thank you !) I will protect against the leak you suspect by inserting a one way valve in the line between the T and the micro switch. Should solve that problem as you would need a simultaneous leak in two components, both the NRV and the micro switch before you lost all air, extremely unlikely. ( By the way in this shot the hoses on the switch are transposed.)
I have had an air micro switch on the nose gear door of my. BVM F4 which is actuated on every flight by the nose leg which signals all doors closed, still working perfectly after 12 years.
I guess nothing is absolutely certain as discovered by the captain of the Polish Boeing 767 when both his primary and alternate gear extension system failed and he landed wheels up at Warsaw !
Regards,
David.