AOPA Pilot Magazine - August 2020 - 76

The Piper PA-24-260
Comanche is a comfortable,
capable traveler with decent
speed, long range, and good
useful load. At maximum gross
weight of around 3,200 pounds
and at 3,300 feet density altitude, it will still climb at 1,100
fpm. Even over gross by about 4
percent it has good performance.
Four percent over gross
with an engine producing a little less than full output, it will
fly and climb. Over gross with
a sub-par engine and a center of gravity some 2.2 inches

the student pilot had flown
together. The student pilot had
neither a medical nor a student
pilot certificate. The CFI had
some Comanche time, but his
only flight in the mishap airplane was the flight down to
Scottsdale, which had originated from Las Vegas just
prior to sunset and landed at
Scottsdale an hour past civil
twilight.
Witnesses reported a
seemingly normal engine runup. The Comanche departed
and during rotation imme-

A CFI with a new student, unaware of the aft CG,
might think it was a problem with pilot skill and at
first be unalarmed-only to learn too late, when he
took full control of the airplane, that the problem
was more complex.
behind the aft limit, however,
the reliable workhorse has virtually no chance. According to
the NTSB final report, those
were the conditions leading
to a crash that took six lives
during what should have been
a fun jaunt from Scottsdale,
Arizona, to Las Vegas in the
spring of 2018.
A CFI flew the Comanche
from Las Vegas to Scottsdale
just prior to the mishap flight.
Ten minutes after landing at
Scottsdale, he began loading
passengers: two women in
the aftmost seats, a couple in
the middle seats, and the student pilot in the left seat. He
departed Scottsdale 20 minutes later-after a total of 26
minutes on the ground to taxi
in, load, brief a new student on
a night cross-country flight,
crank, taxi out, and depart.
NTSB investigators believe it
was the first time the CFI and
76 | AOPA PILOT August 2020

diately began a series of
"extreme" roll oscillations,
which continued after liftoff. The tower controller also
noted the engine sounded as if
it was not producing enough
power, and she asked the
Comanche if they were experiencing any difficulty. A pilot,
likely the CFI, responded that
they were "in training mode."
The oscillations subsided and
the airplane appeared to be
under control, albeit not gaining altitude as expected.
At the departure end of the
runway, the airplane began a
climbing left turn. Witnesses
reported the engine sounded
normal. A voice, likely the
CFI's, began to transmit
what seems to be a change
of plans for departure, but
the transmission was truncated. The Comanche's climb
peaked at about 200 feet agl
and, continuing the left roll,

transitioned to a nose-down
attitude and crashed onto
a golf course-less than 30
minutes after the CFI's initial
arrival at Scottsdale.
By far, the most devastating of the problematic
conditions that hot spring
night was the substantially aft
center of gravity, found by the
NTSB to be at least 17 percent
out of limit. Such an aft CG
would make a Comanche-
and most airplanes-close to
uncontrollable immediately
after liftoff. The nose-up
pitching moment caused by
the aft weight would require
close to, and perhaps exceed,
the available nose- down
elevator authority to fully
counteract. The easy and
quick pitch-up at rotation
would likely cause an early
liftoff, at slower than desired
speed, possibly causing wing
rocks similar to action in
slow-speed or stalling conditions. Control inputs would
be unusual, exaggerated-
it wouldn't feel right-and
the resulting oscillations
would be discomforting for
all. A CFI with a new student, unaware of the aft CG,
might think it was a problem
with pilot skill and at first be
unalarmed-only to learn too
late, when he took full control
of the airplane, that the problem was more complex than
just a student struggling with
a heavy-weight take off on a
moonless night in an unfamiliar airplane.
NTSB investigators noted
a broken intake valve spring
in the number three cylinder that likely contributed to
substandard engine performance. Investigators noted
scoring on the valve spring,
AOPA Pilot Magazine - August 2020

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