AOPA Pilot Magazine - November 2022 - 94

RUDDER & WRENCH
SAVVY MA INTENANCE / OPINION
GUARDING
YOUR LEGACY
Since 1939, AOPA has
fought to protect the
freedom to fly while
keeping general
aviation safe, fun, and
affordable. Today, we
continue investing in
and developing
programs to meet the
needs of current and
future pilots.
You can help create a
brighter future for
general aviation by
becoming an AOPA
Legacy Society member.
When data
doesn't look right
Using AI and deep learning to detect
anomalous engine monitor data
BY MIKE BUSCH
NOWADAYS, MORE THAN half of the piston
GA fleet is equipped with some sort
of recording digital engine monitor. Older
ones tend to be primitive and record just
exhaust gas temperature (EGT), cylinder
head temperatures (CHT), and not
much else. Modern ones have myriad
sensors and capture numerous temperatures,
pressures, voltages, currents, air
data, attitude, acceleration, and GPS position
data. A modern engine monitor with
a few dozen sensors and a one-second
sampling rate records more than 100,000
measurements per hour of flight. This data
can have immense diagnostic value.
In a perfect world, our engine mon "
I
believe in what the
AOPA Foundation is
doing and want to see it
continue. If my wife and I
can leave something behind,
we want it to go where it
can make a difference and to
things we believe in-like our
daughter and general
aviation. "
- George McMillin
AOPA Foundation
Legacy Society member
To learn more, visit:
aopafoundation.org/legacy
itors would analyze all this data in real
time and alert us whenever something
doesn't look right. But even state-of-theart
avionics have an extremely limited
ability to do this. Some engine monitors
will alarm when various data values-
CHTs, turbine inlet temperature (TIT),
oil temperature and pressure, and more-
fall outside user-configurable minimum
or maximum values. Others alarm only
when values hit the manufacturer-specified
redline (which is often way too late
to save the day), while others offer no
alarms at all.
No engine monitor does what our
human data analysts at Savvy Aviation
are trained to do: to look for patterns in
the various sensor values. If cylinder number
3 has an EGT that differs significantly
from the other cylinders, is there a corresponding
divergence in its CHT that
would confirm abnormal combustion, or
could it just be a bad EGT sensor or flakey
94
AOPA PILOT / November 2022
harness? Or if cylinder number 1 looks like
it was starting to flame out when the pilot
leaned for cruise, what were the fuel flow,
manifold pressure, and rpm, and what
were the other cylinders doing?
You get the idea. To really understand
what's going on, it's necessary to look at
lots of different sensor data and integrate
it into a coherent picture. Our human analysts
do this quite well, but our avionics
don't even try-at least not yet.
Drowning in data
Here's the problem: We have more than
5 million flights of piston GA airplanes in
our database, with more than 10,000 new
flights uploaded each week (and accelerating).
Our staff of trained analysts numbers
10 people. Obviously, they can't look at
every new flight that comes in.
Which flights do they look at?
Typically, the ones that our aircraftowner
clients ask to be looked at, generally
because a client believes that their engine
is performing abnormally and they're
looking for a pinpoint diagnosis. Maybe a
client's engine hiccupped or started running
rough or losing power. Maybe the
engine monitor triggered a CHT or TIT
or oil temperature alarm. That's usually
when a client will upload flight data and
ask us to look at it.
We'd really like to do better than
that. We want to be more proactive, to
detect incipient engine problems that the
aircraft owner doesn't even know he
has (yet). To do this, we need to develop
computer software capable of studying
each new flight that is uploaded and
http://www.aopafoundation.org/legacy
AOPA Pilot Magazine - November 2022

Table of Contents for the Digital Edition of AOPA Pilot Magazine - November 2022
