AOPA Pilot Magazine - August 2021 - 96

RUDDER & WRENCH
Savvy Maintenance coverage sponsored by AIRCRAFT SPRUCE
SAVVY MA INTENANCE /OPINION
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Machine learning
This cutting-edge technology could revolutionize
GA maintenance
BY MIKE BUSCH
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THE EXHAUST VALVE is the most likely
component of a piston aircraft engine to
fail catastrophically. When one fails, combustion
ceases in the cylinder, and the
engine loses power and starts running
rough. This usually results in a precautionary
landing-on-airport if you're
lucky, off-airport if you're not. It's particularly
serious with a four-cylinder engine,
because a four runs a lot worse on three
than a six does on five. Occasionally, the
liberated valve fragment gets wedged into
the piston crown, which can shatter the
piston and cause a total power loss, sometimes
with fatal results.
That's why it's so important to detect
incipient exhaust valve failures early
before they can cause serious problems.
The traditional way is the annual compression
test, but that isn't a very reliable
method because loss of compression typically
doesn't occur until the valve is very
sick and close to failing.
A borescope inspection is vastly better
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and can detect failing valves a lot earlier.
The AOPA Air Safety Institute publishes a
great poster to help mechanics understand
what to look for-Google " Anatomy of a
Valve Failure. " Unfortunately, most shops
don't do regular borescope inspections,
and the ones that do typically do them
only at the annual. That may not be often
enough, especially for engines that fly a lot.
96
AOPA PILOT / August 2021
There should be a better way. If your
airplane has a recording digital engine
monitor-and nowadays over half the piston
fleet does-the answer might be hidden
in your engine monitor data.
Predictive analytics
Predictive analytics is the use of data, statistical
algorithms, and machine learning
techniques to identify the likelihood of
future outcomes based on historical data.
Instead of just using data to analyze what
happened, the goal of predictive analytics
is to assess what is likely to happen in
the future.
Over the past decade, remarkable
advances in this technology have been
made in the airline industry. Boeing has
been in the forefront with its groundbreaking
Airplane Health Management program
for the 777 and 787, but Airbus, GE, Pratt
& Whitney, and Rolls-Royce have been
investing heavily in this area. The resulting
capability to use aircraft sensor data to
predict incipient component failures has
been remarkable.
Piston GA ought to be able to benefit
from this technology, too, I thought,
so in 2014 my company launched a program
whose goal was to predict incipient
exhaust valve failures based on digital
engine monitor data. We dubbed it FEVA-
Failing Exhaust Valve Analytics.
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AOPA Pilot Magazine - August 2021

Table of Contents for the Digital Edition of AOPA Pilot Magazine - August 2021
