AOPA Pilot Magazine - September 2020 - 92

P&E

OWNERSHIP

THE NEW D'Shannon baffle kit looks great and seals up the engine compartment well,

directing all available cooling air down through the engine.
A CRACKED crankcase falls into the "calls

you don't want to get" department. Here,
the crack has been hit by an arc welder to
make it more visible and to assure that the
case goes into the scrap pile and is never
used again.

92 | AOPA PILOT September 2020

If there's one must-do with an engine
overhaul, it is replacement of the engine
mounts. I knew that when it was overhauled in 2002, but the shop that did that
installation convinced me that the old
mounts were in good condition and didn't
need to be changed. Clearly, 18 years later,
they had failed and caused damage.
The old baffling was just that. Rather
than piece it back together, I sprung for
a new D'Shannon Aviation baffle cooling
kit. I have to say, it looks great; fits super
tight; and appears to be doing a good job
of cooling the engine.
As you've surmised by now, the pieces
and parts all came back together. The prop
and engine made their way back to Royal
Aircraft and were installed successfully.
The test flights and subsequent breakin period show an incredibly smooth and
fast engine. Flat out it moves the old A36
airframe along at 178 to 180 knots true airspeed. At 75 percent it is typically 172 to
175 KTAS.
Many people commented on how
smooth the old engine was. But the newly
overhauled one is even better. This is like
turbine-smooth.
After about 18 hours of flying with mineral oil, I changed it out for regular ashless
dispersant oil and am on my way to what
I hope is another couple of thousands of
hours of trouble-free flying.
AOPA
EMAIL thomas.haines@aopa.org

LEFT: COURTESY OF PINNACLE AIRCRAFT ENGINES, RIGHT: MIKE COLLINS

regrinding if necessary. All bushings are
honed in house because they believe they
get better quality control that way.
Any new parts are ordered while the
reusable parts move into the paint shop.
New and reusable parts come together
in the rebuild room where all of the parts
are measured again. Pinnacle uses a buddy
system for the reassembly process. One
technician does the build; another checks
the work.
Pinnacle's engine test cell is more
sophisticated than many in that it includes
a downdraft cooling system which closely
mimics the baffling system installed in an
airframe. This improved airflow plus a
water misting system means they can run
the highly instrumented engines longer on
the dynamometer without fear of overheating. Kuti said my engine did so well in the
dyno that they ran it for an extra hour to conduct their regular calibration processes. "We
can see crankcase pressures drop off while
on the dyno," Kuti said, indicating that rings
are often seated during that initial run, which
means much of the break-in process is complete before the engine leaves the test cell.
Kuti said when it was torn down, my
engine looked much as he would expect

of a big-bore Continental run to TBO and
beyond. The lifters had some spalling; the
oil cooler was rejected because of a crack;
and the starter adapter shaft and gear were
worn beyond limits-all common findings.
However, one important and expensive
part didn't pass muster: the crankcase. After
cleaning and upon inspection, Pinnacle discovered a crack that was not repairable. Cha
ching! An overhauled case added $6,500 to
the bill. The original was a "heavy" case-as
opposed to earlier models with thinner cases.
The thicker, heavier cases were introduced
to reduce cracking, but Kuti says they see a
fair amount of cracking of heavy cases. It may
be too much of a good thing, he suggests: the
heavier cases don't flex under stress, which
may lead to cracks. Nonetheless, that is still
the recommended case.
One should go into an overhaul expecting a few "extras" such as that. Royal Aircraft
informed me that the propeller shop was
recommending the prop governor be overhauled as well. As it turned out, the cost
of the overhaul rivaled the price of a new
McCauley governor, so I went with new.
With the engine out of the airframe,
Royal technicians noted that the engine
mounts had sagged enough over the
years to allow the engine to damage the
nose bowl inner panels-wearing holes
through in a couple of places and causing a crack. Because of the complex shape,
they couldn't be repaired with doublers.
New panels were ordered.

AOPA Pilot Magazine - September 2020

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