AOPA Pilot Magazine - October 2020 - 100

P&E 

NEVER AGAIN

Whispers
of trouble
The accident that never happened
B Y R U S T Y H E R R I N GTO N

100 | AOPA PILOT October 2020

room physician. My commute is from
Statesboro, Georgia (TBR), to LaGrange,
Georgia (LGC), one to two times each
week. The flight is 172 nautical miles and
takes about 70 minutes each way in my
highly modified North American Navion.
My engine was a Continental IO-550-B that
was freshly overhauled just a few years ago.
I always changed the oil between 25 and
35 hours instead of waiting until 50 hours.
On two occasions my engine instruments have displayed unusual oil pressure
indications. The first occasion was in June
2016 during a return trip from New Mexico.
The June weather was beautiful and VFR
but very hot all along the route home.
During the flight the oil pressure ran about 5
to 7 psi lower than usual but otherwise acted
normally. Oil temperature was less than 200

SARAH JONES

IF AIRPLANES COULD TALK what would they
say? Well, they can talk if we learn how to
listen and pay attention. Sometimes the
language is subtle, as in a new sound or
vibration. Sometimes they scream, as when
my friend's number 5 cylinder unexpectedly dropped a valve resulting in a broken
piston, complete oil loss, and prompt engine
failure. Some sudden catastrophic failures
are impossible to predict, but others can be
predicted and possibly avoided. As pilots
we should keep a mental note of what our
instruments usually indicate and look for
deviations that could indicate a problem or
pending failure. Just because the indication
is still in the green range does not mean that
nothing is wrong.
I am fortunate and get to fly 300 hours
a year commuting to work as an emergency

degrees Fahrenheit for the entire flight. The
engine ran great and continued to produce
plenty of power. I nervously watched the
pressure as it stayed steady in the green
range and continued our trip home. The oil
consumption remained as usual during that
trip and we arrived home uneventfully.
Once home the oil was changed and
a new paper element oil filter installed.
Prior to this oil change I was using a reusable stainless-steel mesh oil filter that was
removed and disassembled for inspection
at each oil change. On inspection I found
that the steel mesh had accumulated
some residue that narrowed the openings
in the mesh. I reasoned that the oil filter
was restricting flow and oil pressure, so I
returned to using a paper element oil filter that is discarded at each oil change.
The oil pressure returned to normal, and
I returned to flying with my usual oil pressure of 45 to 46 psi in cruise flight.
That engine continued to run great and
showed no problems. Regular oil filter cutting revealed no metal and oil analysis was
always normal-so normal that I skipped
cutting the filter and oil analysis when I
changed the oil in December 2017. I continued to fly my Navion until late February
2018 when something changed. I was flying to work and noticed my oil pressure
was once again lower than usual. It was
down into the middle 30s but remained
in the green range and steady. I increased
rpm from low cruise 2,300 to high cruise
2,500, and the oil pressure returned to the
usual 45 to 46 psi. The oil temperature was
around 160 degrees F, which is the usual
oil temp in cool weather for that engine.
I was concerned about the oil pressure
indication, but I had seen this occurrence
previously. The weather was good and the
pressure was back up to usual so I continued on to LaGrange.
Three days later I returned home to
Statesboro. Now comes the lucky and scary
part. The flight home was night IFR and I
flew the RNAV Runway 32 approach into
Statesboro. Before departing LGC I checked
everything carefully and the oil pressure on
run-up was normal. I watched the oil pressure carefully and flew home at high cruise
power setting. I landed uneventfully at TBR
but noticed that oil pressure at idle was a lot
AOPA Pilot Magazine - October 2020

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