Avionics News January 2017 - 33
it, but it wouldn't be very efficient. When faced with situations
swapping sides and seeing if the problem persists."
like that, we say, sorry, we can't help you."
Once the faulty component has been identified, the rapid
And then the shop draws on its 38 years of experience
response team at the nearest Duncan satellite shop loads the
to connect the operator with another shop, the avionics
needed component and tools and test equipment, and hits the
manufacturer, and others it knows who do have the knowledge
road for the airplane. If it does not have the needed component
and experience necessary to help the operator. "We're here to
on hand, Harpster said, Duncan calls the manufacturer and has
help anyway we can," Prince said.
the loaner, rental or replacement component drop-shipped to
AOGs on Part 23 aircraft are rare, according to Prince, who
where the airplane is on the ground.
can count on one hand the number he's served during the past
At some point in the process of a Part 25 AOG, there's a call
15 years. Troubleshooting them has become easier with digital
to the manufacturer of the component involved. The telephone
avionics because its software includes fault-test programs that
tree depends on the situation and the operator.
help identify the problem. With the source of the AOG accurately
"The owner might call the airplane's director of maintenance
defined, they resolve it with a repair, replacement, a loaned
first, but he might not have the troubleshooting expertise,"
component, or a call to another shop or a call to the manufacturer
Harpster said. "He might not want to tackle the problem
of the component involved. It depends on the situation. The only
because of the added expense of renting and shipping a
after-hours AOG request Peninsula
replacement component, and the cost
Avionics has dealt with was a Hawker
of shipping, testing and retagging it
800 SP, a charter flight bringing its
for future use as a loaner if it does not
IN ANY CASE, AN AOG
passengers to a NASCAR race. "It had
solve the problem." So the director
an EFIS failure. We trouble-shot it,
of maintenance calls someone like
SITUATION IS UNIVERSALLY
and the charter company sent down a
Duncan, or shops like it that are geared
replacement unit that we swapped out."
up and ready for Part 25 AOG calls.
EXPENSIVE, WITH THE
LATTER EVEN MORE SO WHEN
Part 25 AOG complexity
While the fundamental steps of
dealing with an avionics AOG are the
same, the knowledge and experience
of the technician troubleshooting the
problem must be make-and-modeland-system specific, according to Gary
Harpster, senior avionics modification
sales representative at Duncan Aviation.
"New Part 25 airplanes like the Dassault Falcon 7X or the
Bombardier Global Express have more complex, integrated
systems that talk to each other," he said. "It is a totally
different mindset because those aircraft have unique system
idiosyncrasies, and you have to know them to troubleshoot
them accurately. Some components you can't check until the
weight is off the squat switches, for example, so it's critical that
technicians know what they are doing on each make and model."
Experience is equally important with older airplanes, like the
Lear 35, added Harpster, because there are not as many people
around who know, for example, the autopilot system on that
aircraft and others of its era. And the accumulation of this makeand-model expertise is continual as the Duncan network serves
the needs of 150 to 160 aircraft a week.
Duncan gets an AOG call about once a week, Harpster
noted, and the specifics of the situation determines the
members of the emergency response team. First up is the
person with the knowledge and expertise to help the caller
troubleshoot the problem down to the component, which can
involve "swapping out the component, or on a dual system,
What warranties are in effect is
another component of resolving an
AOG situation. "A lot of our end
customers come directly to us," said
Robert Nierenhausen, customer service
and warranty manager for Universal
Avionics Systems Corp. But operators
flying Cessna, Lear, Bombardier and
others that offer extended warranties on their aircraft would
contact the source prescribed in those agreements when facing
an AOG. "And then Cessna, Lear, Bombardier and the rest
would contact us to drop ship the components they need, and we
bill the manufacturer."
Given the reliability of digital avionics, AOG situations
caused by them is not a pervasive problem. "As far as Universal
Avionics is concerned, some of the flight management systems
we sold in the early 1990s are still flying, and we've had a huge
upgrade in the units since then," Nierenhausen said. "But we
support all of them, so we have to have an adequate supply of
support product available for all of the units because I might get
calls for eight of the same units on the same day."
At some point during the AOG process, whether it is for
troubleshooting assistance or to arrange for drop shipping a
component, the avionics manufacturer gets a phone call, he said.
"I've got three people on the phones at all times, and they have
18 to 20 years of experience at Universal. When they hear the
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