January/February 2023 - 22

INSPEC T ION & TEST ING
" What I tell folks is we'd all love to be driving around in a
brand new, decked out Mercedes S-Class, but unfortunately, we
all can't do that. We recognize that there's other vehicle options
that can meet our requirements and fit in our budget. So heated
seats, heated mirrors, other fancy options are nice to have, but
do you really need that to get from Point A to Point B? And the
same is true of borescopes, " French said.
In aviation, having an articulating borescope, one where a
technician is able to maneuver or steer the tip of the probe in
different directions, is often crucial.
" You're able to maneuver or steer the tip of the probe in different
directions. And so, some do that in two ways. Some do it
in four-way. Others do it in a joystick, 360 degrees, " said French.
Another factor to consider is reachability.
" If it is for aircraft engine inspection and general use, the internal
accessibility port, length and the angle view to the blades required
for the borescope will dictate the best choice for the borescope. The
most common borescope size used is a 3.9-4mm or 6mm diameter
with a 1 ½ meters to 3 meters length, " said Ewert.
Ito adds that since various types of engine inspections are
required, from small engines in small aircraft, such as helicopters
and business jets, to large engines in large passenger aircraft,
scope choice will change depending on the job.
" Borescopes with different scope diameters and insertion
lengths are required for each type of engine inspection. For this
reason, a borescope with interchangeable scopes is efficient in
terms of saving costs and managing inspection equipment when
various types of engine inspections are required, " he continued.
Then comes observational performance. French says image quality
can be a big difference maker when deciding on a borescope.
" Are you okay with VHS quality, or do you want DVD, or do
you want Blu-ray? The image quality is a big difference, " he said.
With image quality also comes image capture, with some
probes able to capture multiple angles and switch between different
points of view with just the press of a button.
" Some of the newer systems that we offer have a dual-camera
probe, " French said. " So the probe has a front-facing camera and a
side-facing camera on one probe. And that makes it nice for guys
in that they don't have to worry about losing a tip, cross-threading
a tip, pulling the probe out to have to put a tip back in, then try
to get back in the same spot. You just push a button, and you can
toggle between those two views. "
Finally, Ito explains that diagnostic performance should always
be considered for borescope needs.
" It is important to select a borescope with the excellent resolving
power and a wide measuring range that can measure defects
such as cracks, corrosion, curls and dents from a greater distance.
This can be done using a measuring optical adapter with a deeper
depth of view (DOF) and a wider field of view (FOV).
" While the wide measuring range is useful for measuring large
defects, the ability to measure from a greater distance provides
another important advantage - inspection speed, " Ito said.
22 JANUARY/FEBRUARY 2023
Borescopes are delicate instruments and require a delicate touch.
EVIDENT SCIENTIFIC
Putting It to Use
Once the right borescope for a technician's needs is in hand, the
next step is knowing how to use it. Each borescope will have a
learning curve to it which can vary depending on its features,
said Ewert.
" There is a learning curve on first use of a borescope. Utilizing
the borescope features will take some time hopefully supported
by clear manual instructions, " he said.
Ewert said some general rules of thumb include first reading
the manual and verifying the internal features and limitations
of the borescope.
" Test and understand the articulation, lighting control, image
capture, image storage. Determine how you will set up your physical
body and scope position to maximize the ease of inspection, "
he continued.
For those looking to become certified and all-around masters
of borescope-based maintenance, there is advance training that
can be undertaken. Using airlines as an example, Ito said postemployment
certification consists of three main levels of training:
1. Post-employment training to obtain aviation-related national
certifications. Examples include national certifications for
mechanics from the Federal Aviation Administration (FAA),
European Union Aviation Safety Agency (EASA), and Civil
Aviation Administration of China (CAAC). This training takes
approximately five years to complete.
2. Training to obtain in-house certifications for each aircraft
model and engine model takes about six months to one year
to complete.
3. Continuous training is required to obtain new internal certifications,
renew certifications and maintain certifications.
For those who merely need to use a borescope routinely or less,
French said there a number of factors to keep in mind to ensure
the equipment is protected and used properly. First is heat.
" Some of the borescopes out there will have a temperature
sensor at the tip. So if the mechanic puts it into the engine, the
engine's too hot, it'll give a warning on the screen to remove the
borescope and, 'It's too hot. Cool it down.' Others don't do that,
AIRCRAFT MAINTENANCE TECHNOLOGY
January/February 2023

Table of Contents for the Digital Edition of January/February 2023
