DG Questions

Jay,

Two can die close together if you lost or the previous owner lost a
vacuum pump and did not check for backwash in the lines from the
intruments to the pump. Carbon has been know to get sucked back into the
lines and make it into the instruments.

Michelle

Jay Honeck wrote:

Six weeks ago my attitude indicator gave up the ghost, after slowly dying
over a period of several months. It's been replaced with a re-built unit
that's working fine.

Two days ago my directional gyro abruptly failed. It worked fine flying
into Pella, and it didn't work at all flying out. The thing wouldn't spin
up at all -- as if the gyro failed catastrophically, or, perhaps, a vacuum
line had come detached. The setting button would pop out, and the thing
would momentarily spin (10 degrees or so), but nothing would happen from
that point on.

My A&P says all the lines look fine, so the cheap fix is apparently out
(naturally). This leaves the DG -- and, of course, it's the real expensive
one with the heading bug for my autopilot...

Doesn't it seem just a little weird to lose both vacuum instruments in a six
week period? Is there any way my vacuum pump could still be putting out 5
inches of suction, and somehow sending junk into the instruments? Could the
AI failure last month have influenced the DG failure this month?

Or is it just bad luck that they've failed together? Any opinions?



--

Michelle P ATP-ASEL, CP-AMEL, and AMT-A&P

"Elisabeth" a Maule M-7-235B (no two are alike)

Volunteer Pilot, Angel Flight Mid-Atlantic

Volunteer Builder, Habitat for Humanity