|
Message
Greetings,
Well, I got the plane
hauled back to the hanger, and managed to find the problem. I had fully
expected to find the oil cooler (evap core) split at one of the seams in the
tank, but I couldn't see a thing wrong with it. After wiping off the oil,
and checking all the oil components, I still couldn't see anything
wrong.
At that point, I drained
the pan, and only measured 1/3 quart. This is clearly below the oil
pickup, which is at least a half inch off the bottom of the pan due to the
sandwich mount plate. I proceeded to remove the oil cooler, and inline
filter. The filter wasn't plugged, or collapsed, though there are some
flakes of something in it. Even on the workbench, the cooler looks
absolutely fine, but it isn't. Blowing through it demonstrates a definite
leak at one of the seams on the tank.
If you look at the way
these are constructed, the core is made up of a number of layers, stacked
together like slices of bread. To close up the open ends of the tanks,
there's about a 1/16" aluminum plate brazed at the end of the tanks. The
seam between this plate, and the main part of the core is what leaked on both of
my oil cooler cores. The attached pictures show an old core that Ed
sent me to do some testing with a couple years ago. It had developed a
leak from what he believed to be too much strain/vibration on the hoses.
Both of my oil cooler evap
cores leaked at this same seam. The latest one was on the end of the tank
with the fitting that I welded on. You could suppose that the welding
process overheated the seam, and caused it to leak, however, it sure took it's
time (at least 10 hours for this one, and about 30 hours for the first one)
deciding to leak. You could also suppose that the strain on the hose
caused fatigue. My oil hose is long, and has lots of room to flex. I
just can't imagine that putting any strain on the oil cooler fitting. The
first leaking oil core happened on the end without the welded fitting,
though that one was dented in. In other words, welding, or strain
from a fitting couldn't have been the cause in that
case.
I find it too much of a
coincidence that my two water cores have not had any problems, yet both of
the cores I've tried on oil have leaked at the same point of
construction. Of course Ed did have a water core that leaked at the same
point. Bottom line is that this seam seems to be the weak point of these
cores. I can't explain exactly why they're failing, but I have to conclude
that they aren't so robust as I'd like them to be. I'd be interested
to know if this is where they commonly leak on cars as
well.
As for the engine, all
6 rotor faces seem to have even compression when turned by hand.
Unfortunately, I'd have to say that the compression is considerably less
than it used to be. The engine will definitely have to come
apart.
As for the plane, I've
already received one email asking if I want to sell it, so I might pursue
that. As you know, only a couple weeks ago, I was saying that I
planned to sell the RV-3, and transplant the engine into an RV-7.
Well, the plane's apart, and I would end up putting a significant amount of time
into getting it back in the air. With that in mind, I'm thinking that it
might be just as well to go ahead and sell the airframe now. Haven't
decided for sure, but I could see getting the Slingshot back together in
fairly short order with the 912S, then either starting on a single rotor
conversion for the Slingshot, or starting on an
RV-7.
Cheers,
Rusty
(undecided)
|