AOPA Pilot Magazine - February 2019 - 89

AOPA

Be thoroughly skeptical any time an aircraft
comes out of the shop.
failure to properly secure the bolt connecting the throttle cable to the carburetor
during the installation of the carburetor,
which resulted in a loss of engine power."
In November 2016, a Cessna P210 crashed
near Pleasanton, Texas, only a few hours following recent maintenance. The commercial
pilot reported that, about 20 minutes into the
cross-country flight, the engine suddenly
experienced a partial loss of power. During
the subsequent forced landing on a road, the
airplane struck a car, resulting in substantial damage to the fuselage and both wings,
and injuring both occupants of the airplane.
Examination of the airplane revealed that
the hardware that attached the throttle linkage to the engine was not present. Probable
cause: "Maintenance personnel's improper
installation of the throttle linkage attachment
hardware, which resulted in a partial loss of
engine power when the hardware separated
in flight."
In April 2016, a flight instructor and his
student departed normally from the San
Carlos, California, airport and climbed to
an altitude of 1,000 feet above ground level.
The pilot attempted to reduce engine power
to a climb power setting, but the engine was
unresponsive to throttle inputs. The pilots
returned to the airport, pulled the mixture
control to the idle cut-off position when
the airplane was over the runway threshold, and landed uneventfully. Examination
revealed that the throttle cable had broken.
Probable cause: "The failure of maintenance personnel to properly install and
secure the input swivel boot on the swivel
joint, which resulted in excessive vibration
that led to fatigue cracks and failure of the
throttle cable."
In July 2013, a Mooney M20J crashed
near Leonardtown, Maryland, injuring the
pilot and his flight instructor. They were practicing instrument maneuvers at about 1,500
feet mean sea level when the engine stopped
responding to throttle control inputs and
producing enough power to maintain level
flight. The pilots chose to land in a field,
which resulted in substantial damage to

the fuselage and wings. A bolt and nut were
found resting on the bottom of the cowling,
and the throttle arm linkage was not connected to the throttle body arm. Probable
cause: "The improper installation and
inspection of the throttle linkage by maintenance personnel, which resulted in the
throttle linkage coming loose and a subsequent partial loss of engine power."

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ERRORS OF DISTRACTION

Distractions often play a big part in such
maintenance errors. A common scenario is
that a mechanic installs nuts or bolts or ignition B-nuts finger tight, then gets a phone
call or goes on lunch break and forgets to
finish the job by torqueing the fasteners. I
have personally seen some of the best, most
experienced mechanics I know fall victim to
such seemingly rookie mistakes. Many fatal
accidents and countless less-serious incidents have been caused by such omissions.
Just as pilots need a sterile cockpit
during high-workload phases of flight,
mechanics need a distraction-free workplace when performing safety-critical
maintenance tasks. Unfortunately, the
typical small piston GA shop is a distraction-rich environment. Phone calls come
in. Customers drop by unexpectedly. UPS
and FedEx drivers deliver anxiously awaited
parts. The Snap-On tool truck stops by. The
shop's FAA principal maintenance inspector pays a surprise visit.
Aircraft owners and pilots need to be
mindful that maintenance errors create a
significant hazard, and must act accordingly. The most likely time for an aircraft to
experience a mechanical problem is on the
first flight after maintenance. Be thoroughly
skeptical any time an aircraft comes out of
the shop. Your preflight and post-maintenance test flight are the last line of defense
against maintenance errors.
AOPA
MIKE BUSCH is an A&P/IA.
EMAIL mike.busch@savvyaviator.com

www.savvyaviation.com
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AOPA Pilot Magazine - February 2019

Table of Contents for the Digital Edition of AOPA Pilot Magazine - February 2019
