spring2022 - 12

COVER STORY
requires very specific processes, procedures
and equipment for proper alignment and
calibration to achieve optimum accuracy,
Olivastri said. " We support the end user
with hands-on initial training and refresher
training. We assist with in-country troubleshooting
and problem solving to ensure this
essential piece of equipment does not cause
their aircraft to be grounded. "
Elbit Systems HUDs must be certified by
the applicable civil authorities to the highest
design assurance level since they are utilized
as the pilots' Primary Flight Display.
This means that a failure of the HUD would
ultimately cancel the mission or ground
the aircraft.
An improperly calibrated HUD could
result in multiple issues such as blurry or
shifted imagery, display brightness while display
refresh issues could cause a noticeable
blinking of the image.
For the optics, chips and scratches could go
unnoticed. A chip or scratch within the field
of view (FOV) may seem like very minor issue
but could result in a profound effect on the
pilot's ability to read the display
" All these calibration and optics issues
may go unnoticed for the untrained maintainer
but could result in critical information
unreadable by the pilot resulting in an unsafe
operating environment, " Olivastri said.
Bigwood said Excelitas supports all of its
HUDs throughout the lifetime of the aircraft.
HUDs are sent back to its facility for inspection
and test. Excelitas determines if repair
is viable or whether the HUD is beyond economical
repair (BER). In most instances, the
company can maintain/repair the HUD and
re-life the product getting it back to the user.
" As an OEM, we can re-manufacture
failed or damaged elements, or in some cases,
re-work components to restore their as-new
condition, " he said. " All repaired HUDs are
then fully tested prior to return to the platform
integrator. "
If there is a suspected fault in the avionics
head-up display system, Bigwood said a team
of specialists exchange the line replaceable
unit (LRU) to maintain operation of the aircraft.
The suspect LRU will then go to the
airbase or airline maintenance back shop
Excelitas Technologies offers holographic combiners used on many of the
military platforms.
for further diagnosis. Using the repair procedures
created with Excelitas expertise, the
HUD is diagnosed and either repaired by fitting
Excelitas supplied replacement sub-assemblies
or returned to Excelitas is the OEM
where the LRU can refurbished.
Keep an Eye on
Combiner Damager
Bigwood said the most common issues are
damage to the combiner, where if used as a
step for entry and exit to the aircraft, they
can get damaged. Sometimes on commercial
airliners, the combiner is used as a handle
for the pilot to haul themselves out of
their seat. This can cause wear in the combiner
mechanism.
If a combiner is scratched, Bigwood said
it needs to be returned for repair or replacement,
otherwise it can obscure symbology.
Similarly, if the combiner mechanism is damaged,
it needs to be returned to the OEM for
strip down and repair.
" Combiner damage is visible by inspection
and mechanism operation is simple to assess
by exercising the stow and deploy operation, "
he said. " The HUD projector assembly is a
sealed and purged unit, which has a main12
e-Military Product News For Aviation * SPRING 2022
tenance schedule. If there is a reduction in in
image brightness of the HUD, a re-purge may
be the solution or a replacement of the display
source itself might be necessary. "
If you wear a ring, Kowash said to be careful
working around the Combiner to avoid
chipping the glass edges. When deploying the
Combiner, let the arm snap into the detent for
repeatable positioning.
" One unique procedure some of our systems
may require when swapping LRUs is
electronic alignment, " he said. " To accurately
provide precision flight information to pilots,
HUDs and EFVS sensors must be aligned to
the outside world with tight tolerances. When
replacing LRUs, it may sometimes be required
to confirm or recalibrate this alignment using
electronic adjustments. Collins provides
detailed instructions for these procedures. "
Excelitas Technologies
spring2022

Table of Contents for the Digital Edition of spring2022
