Most of the time it is because the Vac filter has not been changed or there is a hose off and the gauge is sucking unfiltered air.Yesterday I'm noticed "foggy" glass inside turn coordinator and airspeed indicator . Should I be worried ? Can anyone explain why it happens and what can I do to prevent it?
Thanks
I don't think there are any vacuum driver turn coordinators in existence, so it would have to be something else. And even in the case of vacuum instruments, there's nothing between the instrument and the outside air on the back side to prevent airborne moisture from propagating into the instruments when the pump isn't running. Dust, yes; moisture, no.Most of the time it is because the Vac filter has not been changed or there is a hose off and the gauge is sucking unfiltered air.
I don't think there are any vacuum driver turn coordinators in existence, so it would have to be something else. And even in the case of vacuum instruments, there's nothing between the instrument and the outside air on the back side to prevent airborne moisture from propagating into the instruments when the pump isn't running. Dust, yes; moisture, no.
I don't think there are any vacuum driver turn coordinators in existence,
Those are nice pictures of turn-and-bank indicators, and I've seen vacuum-driven T&B's before. However, they are not a turn coordinator (of which I've never seen a vacuum-driven version). For an explanation of the difference (including pictures) between the two different instruments, see the Instrument Flying Handbook, pages 5-20 to 5-22.Yes there is, the turn coordinator in the
F-24 was a vac driven instrument, as is the one in the 48 170.
If you were referring to TC's, I agree. However, as Tom pointed out, there are some old vacuum T&B's out there, generally dating back to the venturi days when a separate venturi for each instrument was considered an independent power source so three venturies powering three vacuum-driven gyro instruments (T&B, AI, and HI) was legal for IFR. And I was talking strictly about vacuum-driven gyros, for which there is no moisture barrier at all (including the air filter, which only deals with particulates).These instruments (electric) are sealed and have gaskets. If moisture is present remove, send to instrument shop and have repaired correctly.