AOPA Pilot Magazine - January 2014 - 38

PILOT BRIEFING
AOPA sweepstakes coverage sponsored by BANK OF AMERICA

HIGH-DEFINITION endoscopic
views show signs of even
temperature patterns and a
few deposits on the exhaust
valves (left). Intake valves
run cooler, and thus have
no heat-related issues (top).
Cylinder walls showed minor
pitting (left side of photo,
above).

The top end, in depth
Borescoping the Debonair's cylinders
BY THOMAS A. HORNE
I HAVE GOOD NEWS and bad news. The good news is
that when we bought the Debonair Sweepstakes airplane back in the summer of 2012, we inherited an
engine with just 140 hours since a major overhaul.
The bad news is that that engine had essentially been
sitting for the previous five years. Do the math: 140
hours divided by five equals a scant 28 flying hours
per year. My guess is that most of those hours were
spent flying locally, with plenty of touch-and-goes to
stay current.
So for months on end, the airplane's engine was
stopped. This kept oil from protecting the internal
components and allowed moisture to condense on the
cylinders' steel walls. Over time this caused deposits-rust!-to form on those walls. That rust showed
up after we gave the airplane its first oil change,
and the oil analysis sample showed high levels of
iron-a sure marker of wearing steel components.
Oil-analysis laboratory Blackstone Labs (www.black
stone-labs.com) sounded a cautionary note, advising
us to keep flying the airplane, and change the oil at
10-hour intervals to see if iron levels drop.
Which we did. After all, the engine runs well, its
cylinder compressions are good, and the airplane
makes book speeds and fuel consumption rates.
When the airplane had its interior work done, Air

38 | AOPA PILOT January 2014

Mod installed an Airwolf remote-mounted oil filter. Its paper element, we hope, will help catch any
iron/rust floating around and recirculating in the oil.
The ten-hour oil change intervals also would help in
flushing out any old iron particles.
But we were curious. How bad could the cylinder
walls be? Select Aircraft Service at Ohio's Clermont
County Airport did a borescope exam and the results
were somewhat discouraging. There were signs of
pitting and wear. But iron levels came down in the
second oil analysis report. Maybe the rapid-flush
strategy was working, and eventually the engine
would be freed of the excessive iron.
The next 10 hours of flying involved two very
long cross-country flights of five hours each. Then
came a leg of two hours. The extra 40 gallons of fuel
provided by the tip tanks let me fly from Clermont
County to AOPA Summit at Fort Worth's Meacham
International Airport and back, all the while running
the fresh oil through the Airwolf's conventional paper

ON THE

WEB

VIEW THE

VIDEO

WATCH the

borescope process
in this online video.

FOLLOW Tom Horne's blog (http://blog.aopa.

org/sweepstakes_logbook/) for updates on
the renovation, as well as related news.

http://www.blackstone-labs.com http://www.blackstone-labs.com http://blog.aopa.org/sweepstakes_logbook/ http://blog.aopa.org/sweepstakes_logbook/ http://blog.aopa.org/sweepstakes_logbook/

AOPA Pilot Magazine - January 2014

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