Rotax 914 Turbo

Figure out where the Oil originated from.

Clean up everything and give it a short run then reinspect.

Recent OIL Change...  Confirm that the Oil filter was tightened.

It should have been tightened 3/4 (270°) from the point where the gasket first made contact.

Before touching anything, Mark the TOP of the Filter.

Now try to loosen it One (360°) turn. Lefty Loosey!

If it can be turned without a filter wrench, it is way too loose.

Now start to tighten it until it starts to seat.

Your top mark should now be somewhere near the 3 o'clock position.

If so, tighten it 3/4 of a turn to the 12 o'clock position.

Otherwise, make a new mark and then give it 3/4 of a turn.

Your mechanic should have placed painted witness marks on the filter rim and the engine casing to show that it was properly tightened.

How do those marks line up???

 The next thing to Check is that the Turbo Oil Sump is not "Coked Up".

The Oil is pumped to the turbo bearings and then drips into the sump where it is sucked back to the Oil tank.

If the drain Line is clogged with charred Oil (Coke) debris, the sump will overflow and oil will end up in the exhaust one way or the other.

Oil filter and quick drain area showed no evidence of leaks as I stated. There were only a few drops of oil on left bottom cowling. No evidence of major liquid oil spill/loss. Filter and quick drain were tight. 

Staining on belly suggested smoke not liquid oil.

Mechanics will work on it this week. 

Perhaps related to the turbo oil system. There is a very good video describing that system on this website.

Initial reports from mechanic:
 No metal in filter or scavenger pump. There were flakes of what appear to be brass in oil sump on bottom of turbo likely from bearing. Turbo blades, exhaust side were bent. Abnormal play found in turbo shaft. One supporting bracket for turbo was cracked indicating vibration prior to failure. No evidence of oil "coking".
Oil analysis, bore scope pending.
Link to photos is shown below. Any advice comments or reports of anything similar are welcome.

https://www.dropbox.com/sh/wmrghn7hcl1soqq/AAD4-QWE9vev5zNPsGa8cw8pa?dl=0

It sounds like the summary is that the Exhaust side Turbo bearing failed, causing the turbine blades to bend when they contacted the housing wall an also allow for the uncontrolled release of Oil into the muffler and out the exhaust creating all the smoke.

It is not certain whether the cracked bracket caused to bearing to fail under vibration or the vibration caused by the failed bearing caused the bracket to fail.

In either case, a replacement Bracket and Turbo Assemble are in your near future.

It is not a welcomed answer to the Missing Oil question, but at least it is a solid answer.