AIRCRAFT APPRAISAL
DE-ICING SYSTEM GRADING
CRITERIA
Wing and Horizontal and Vertical
Stabilizer Anti-Icing Systems for
Aircraft Appraisals
The wing leading edges, or leading edge slats, and
horizontal and vertical stabilizer leading edges of
many aircraft make and models have anti-icing
systems installed to prevent the formation of ice
on these components. The most common anti-
icing systems used are thermal pneumatic, thermal
electric, and chemical. Most general aviation (GA)
aircraft equipped to fly in icing conditions use
pneumatic deicing boots, a chemical anti-ice
system. High-performance aircraft may have
“weeping wings.” Large transport-category aircraft
are equipped with advanced thermal pneumatic or
thermal electric anti-icing systems that are
controlled automatically to prevent the formation
of ice.
In the NAAA Certified Aircraft Appraisal, our
appraisers consult the following condition rating
criteria.
#10 Rating:
De-icing boots condition are flawless. Rubber is
soft, no blemishes, and appear to be in new
condition. The age of the boots may be no more
than one year old if the aircraft is stored outside,
and no more then two years old if stored inside.
#9 Rating:
De-icing boots condition are almost flawless and
met the #10 rating criteria except for the age of the
boots since installation. The boots will have no
physical evidence of any deterioration except they
may not be shiny, although they will be soft to the
touch. aircraft appraiser
#8 Rating:
There are no patches on the de-icing boots and the
adherence to the airframe surfaces is excellent.
The boots are losing their glossy look and in
general no longer look like new but do not show
any evidence of dry rot.
#7 Rating:
Generally the boots would have a rating of #8
except there may be one or two patches which
have been properly applied and are adhering to
the surface of the de-icing boot.
#6 Rating:
There may be several patches or other boot repairs
which have been done properly. Additionally there
may have been some boot repairs, such as re-
adherence to the airframe etc. The boots appear to
be dull but are not dry rotting.
#5 Rating:
Several patches and repairs have been
accomplished. The texture of the boot is beginning
to harden and tiny hair-line cracks are beginning to
become visible. The boots are functioning properly
and are in airworthy condition.
#4 Rating:
Boots are beginning to show definite signs of dry
rot. Additional evidence of the condition is shown
by the number of patches existing on the boot.
#3 Rating:
Boots look poor, dry rotting is very evident,
patches numerous and in general the boots are
ready for replacement although they still appear to
be functional.
#2 Rating:
Boots are no longer airworthy and must be
replaced.
#1 Rating:
Boot de-icing system is in need of repair and boot
replacement. Estimate of repairs required for de-
icing system repairs.
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