AOPA Pilot Magazine - June 2015 - 77

Arizona, for initial PC-12 training
in early May 2012-about a month
before the accident. The pilot
received four extra flight lessons
in the accident airplane, accruing
a total of approximately 19 hours,
with about three hours of actual
instrument time. The procedures
portion of the training included
about 20 hours of ground instruction covering the airplane and its
systems, and 12 hours of instruction in a fixed training device.
The pilot's training records
were satisfactory. Unusual-attitude
recovery with unscheduled trim
activation (stabilizer, aileron,
and rudder) was practiced in the
FTD and in the accident airplane.
Autopilot test procedures were
demonstrated along with autopilot
malfunction. The pilot was signed
off for a flight review, instrument
proficiency check, and high-altitude endorsement.
WEATHER. There was no record of
the pilot receiving a weather briefing from an approved source, but
he may have obtained weather
from some other source. A stationary front across northern Florida
was producing scattered light
rainshowers and thunderstorms.
However, no organized area of convective activity or icing was near
the accident site and the NTSB did
not consider weather to be a factor.
THE AIRCRAF T. T h e P i l a t u s
PC-12/47 is a low-wing, T-tail, single-engine airplane with flight load
factor limits (flaps up) of plus 3.3
to minus 1.32 Gs. The maximum
maneuvering speed is 163 KIAS,
maximum operating speed is 236
KIAS, and maximum diving speed
(VD) is 290 knots (an engineering
flight test speed used during certification and well above the red line;
it's not something pilots should
ever approach deliberately).

The airplane was manufactured
in 2006, received its annual inspection in January 2012, and had less
than 1,300 hours total flight time.
There were no records of autopilot
malfunction in the aircraft history.
The NTSB could find no preimpact failure in the flight control
system, the aircraft structure, the
engine, or the autopilot. The CAWS
system provided investigators with
a comprehensive view of aircraft
history, performance, flight path,
and systems function from well
before the accident until impact.
The investigation, much abbreviated here, went to great length to
determine why the autopilot may
have disconnected, and the components were extensively tested. Had
the pilot disconnected the autopilot, it seems unlikely that he would
have initiated a subsequent test.
According to the NTSB report,
"The flaps were found in the
retracted position, and the landing gear was extended; it is likely
that the pilot extended the landing
gear during the descent. The horizontal stabilizer trim actuator was
positioned in the green arc takeoff
range, the impact-damaged aileron
trim actuator was in the left-wingnearly-full-down position, and the
rudder trim actuator was full nose
right. The as-found positions of the
aileron, rudder trim, and landing
gear were not the expected positions
for cruise climb (italics added).
"Examination of the relays, trim
switch, and rudder trim circuit
revealed no evidence of preimpact
failure or malfunction, and examination of the aileron trim relays
and aileron trim circuit revealed
no evidence of preimpact failure
or malfunction; therefore, the reason for the as-found positions of
the rudder and aileron trim could
not be determined (italics added).
Impact-related discrepancies
with the autopilot flight computer

precluded functional testing. The
trim adapter passed all acceptance
tests with the exception of the aural
alert output, which would not have
affected its proper operation."
It is also possible that the pilot,
in the stress of the moment, manually applied trim through the
yoke-mounted trim switch-but
that is speculative.
The NTSB reviewed FAA
Service Difficulty Reports (SDR)
from 2009 through 2014 and
found none for the accident aircraft, and only two that discussed
rudder trim or yaw damper; neither
was applicable to the accident aircraft. An aside: One of the largest
PC-12 operators had no data concerning uncommanded autopilot
disconnects.
PROBABLE CAUSE. "The NTSB
determines the probable cause(s)
of this accident as: The failure of
the pilot to maintain control of the
airplane while climbing to cruise
altitude in instrument meteorological conditions following disconnect
of the autopilot. The reason for the
autopilot disconnect could not be
determined during post-accident
testing. Contributing to the accident
was the pilot's lack of experience in
high-performance, turbo-propeller
airplanes, and in IMC."
COMMENTARY. An obvious question
is why a private pilot with fewer
than 800 hours was flying a PC-12
solo. This is not to deny anyone the
opportunity to fly high-end equipment, but history is illustrated with
fatal accidents involving the financially gifted but aeronautically
inexperienced. That's a tough call,
because many complete training
and are successful by being cautious-and easing into the left seat.
Before getting too sanctimonious, however, let's look at some
facts. In 1987 the FAA amended
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AOPA Pilot Magazine - June 2015

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