Emergency Landing today

Took off from KASH this morning and, shortly after take-off, noted that my
oil pressure indicator was jittery -- usually it's pretty steady but today
the needle was a bit jumpy. Wanting to believe it due to a gauge
malfunction, I pressed on for a bit while trying to figure out what kind of
gauge malfunction would cause this problem. (This attempt was
unsuccessful).

The pressure remained in the green, and there were no changes in oil temp
or engine sounds.

However, when directly over KSFM some of the needle jumps were hitting the
top of the yellow, so I decided (finally) that being on the ground was a
real good idea. Declared an emergency and asked for the fire/rescue
equipment to be available (note to self: call back FAA Monday; first time
after an emergency that they've called me).

On the ground there was a definite oil leak coming out where the vacuum
pump is mounted. And I'd lost two or three quarts of oil.

The rear accessory case of my Lycoming IO360 has an oil scavenger pump (for
my RayJay turbonormalizer) and then, attached to this pump, my vacuum pump.
When we removed the vacuum pump, the Garlock seal that belongs in the
scavenger pump was loose and sitting on the vacuum pump shaft.

That Garlock seal was changed last December -- about 70-75 hours ago. It
was still in place on that occasion, but was clearly leaking.

The vacuum pump was changed about 15 hours ago due to malfunction of the
previous one after about 750 hrs.

The mechanic cleaned things up; replaced the seal; checked the screen and
filter (found what he considered an acceptable amount of metal); and
changed the oil. He ran it up and found no evidence of an oil leak after
this repair.

But what could have caused the Garlock seal to come out of the pump? He
did not know. Could there be something else going on with the engine or
the pump? Or is just one of those things unlikely to recur?


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)