Arrow auto gear extension oddness

James M. Knox wrote:
snip

: It doesn't take MUCH movement of the gear door to be enough to let one of
: those little microswitches come on (they are notorious for not going off
: even with the gear up - and get adjusted and adjusted, until they break).
: That far back (where the gear doors are) is probably a lower pressure area
: (try to close the cabin door in flight some time G) and the extra speed
: pulled it out a few millimeters.

The landing gear doors aren't directly actuated by the hydraulic system;
there is a mechanical linkage to the nose gear. The last couple inches of
travel pulls the nose gear doors closed. As you say, a very small amount
of downward creep of the nose gear will cause the gear doors to open a
considerable amount. Add the low pressure area trying to pull the doors open
to a tiny leak in the actuating clyinder and you'll see just this phenomenon.

: Another likely factor... this is an older Arrow 180. They came with 1400
: PSI switches. The 1400 PSI system was marginal. Newer ones came with 1700
: PSI, which held the gear doors shut better (and for longer periods of
: time). Many (but not all) have been upgraded, but we don't know if this
: one has.

Ah, I did not realize that.

--
Aaron Coolidge (N9376J)