Avionics News January 2014 - 35

Rockwell Collins'
Pro Line 21,
shown here as a
retrofit for Falcon
50/50EX, brings
next-generation
avionics
technology on
8-by-10 inch LCD
displays.

According to Gary Harpster, senior avionics sales manager for
Duncan Aviation, "Looking into the near term, supportability is
the primary issue with CRT longevity. A lot of DOMs (directors
of maintenance) pride themselves on the dispatchability of their
aircraft, and owners like this. But when a component like a CRT
becomes long in the tooth and reliability becomes an issue, it
becomes a sore subject real fast.
"While repair is an option, it's not as easy as you might think.
These units were designed and certified nearly 30 years ago. And
when you put them on the bench today, it still has to meet the
same criteria as it did when it was new. That's a huge challenge
for many shops."
Craig Peterson, director of avionics marketing for Rockwell
Collins, said, "The specifications for color cockpit CRTs have
always been stringent, and very few companies ever pursued this
market. With the technology becoming obsolete, the sources of
supply have declined to just a couple. Typically, CRTs will last
for at least six years in commercial and regional aircraft that are
in continuous service."
The problem identified by these experts was that while you
can repair a CRT-based EFIS unit, even the best-intended repair
could have significant repercussions to other components that
can quickly raise the repair costs.
"You can imagine how faded out a 28-year-old TV would be,"
Harpster said. "To meet the original specifications, the technician's options are to turn up the RGB (red, blue and green) guns
or run more juice through the tubes to get the colors up there.
But then the colors start to bloom, and you lose sharpness. In
addition, when you increase the power, you are putting a huge
extra load on the old power supply, which has been at best stable

and probably degrading for years. Ultimately, this will shorten its
service life even more."
Speaking of service life, how will you know when the CRTs in
your panel are heading for problems?
"Some signs the display is heading for future trouble would
be seeing the time to power up the unit getting progressively
longer," Beazley said. "The colors will not be as bright and
crisp. And probably the loudest message will be when the first
display fails."
Beazley explained that the displays are manufactured and
shipped as part of a complete aircraft set. Once the airframe
OEM (original equipment manufacturer) receives them, they are
installed on the same aircraft. This means they are all exposed
to the same environment, good and bad. When one display fails,
the odds skyrocket for a near-term failure to a sibling unit.
The CRT Replacement Path
According to Beazley, "For now, CRTs are still being repaired,
but the cost for this service will continue to escalate. Additionally, it is estimated that in the 2018 horizon, and even earlier for
certain CRT sizes, the source of some of the critical components
inside a CRT display will no longer be available. The CRTs just
can't do what today's large, flat-panel LCD type units can do."
And while the temptation is to rip out the CRTs at the first sign
of trouble and replace them with ramp envy-generating LCD
displays, there are a few things to consider.
First, how long do you expect to keep the aircraft? If you're
comfortable with the airplane and it meets every mission goal
Continued on following page
avionics news

january

2014

Avionics News January 2014

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