AMT_June-July_2021 - 12

COVER STORY
Supplier Highlight
SEAL Aviation helps prevent, inspects for and removes
corrosion. " It is important to do all work per the maintenance
manuals of the aircraft which may vary, " explained
Jerel Bristol, president and owner of SEAL Aviation. SEAL
Aviation has worked on aircraft straight out of the factory
but more so middle-aged aircraft between 20-30 years of
age and even vintage and military aircraft.
When it comes to prevention, the company works with
preventative compounds, primers and protective chemicals,
performs nondestructive testing by x-ray, eddy current,
ultrasound, penetrant, visual inspections and roto/
flap peening. If corrosion has already taken hold, SEAL
can remove it by blending or cutting the corrosion from
the aircraft. " Similar to human cancer, you don't want to
leave any corrosion behind, or it will come back like cancer, "
Bristol noted.
Modern aerospace paints rely on very specific
metal surface preparation conditions.
ROHNER
" The issue with the current corrosion inhibiting primer systems
Corrosion from dissimilar metals at bonding strap.
SEAL AVIATION
Paint plays an important role in keeping corrosion at
bay. And to ensure proper painting conditions, Rohner
engineers and manufactures paint and de-paint hangar
media blast inserts along with a variety of standalone
paint and blast booths for aircraft component refinishing.
Modern aerospace paints rely on very specific metal
surface preparation conditions. Soft media de-paint
blast process allows for complete removal of all paint and
primer without damaging the soft aluminum airframe. An
alternative method of paint removal is chemical stripping
and mechanical sanding, which can be safely performed
in a paint hangar insert benefiting from continuous ventilation
improving operator safety.
" In all aerospace paint stripping and applications
processes operators must evaluate the presence of
Hexavalent Chromium found in many corrosion control
coatings, " commented Dave Rohner, president and
founder of the company. " Hazardous to both operators
and the environment, Hexavalent Chromium exposure
and discharge limits have strict OSHA and NESHAP
regulations. "
12 JUNE/JULY 2021
contain chromium (VI) trioxide, also commonly known as hexavalent
chromium or CrVI. CrVI is a carcinogen which may increase
the risk of cancer and can decompose into toxic hydrogen cyanide
gas. It is extremely destructive to tissues in the respiratory tract.
Recognizably, this compound is hazardous to workers who are
handling the chemical and applying the corrosion inhibiting primer.
It has been Piper's mission to eliminate the usage of CrVI primers
while still maintaining performance requirements.
Back in 2014, Piper's Materials & Processes Engineering performed
a baseline corrosion assessment of all Piper's production
primers and topcoats to ensure adequate corrosion protection of
interior areas that are difficult to inspect. The scope of the project
was to determine the expected life of primers and topcoats when
put under extreme environmental stresses such as salt fogging
per ASTM B117. The results would help provide a standard for performance
that could later be used to find chromate-free primers.
As of May 2021, Piper has switched the exterior aircraft primer
to a non-chromate alternative, Alumigrip 4101, a magnesium-rich
primer. This is huge win for Piper's initiative to be chrome-free for
the health and safety of its employees and customers.
For newer aircraft, it is important to ensure that there is no missing
primer or paint on the aircraft where there is intended to be
primer or paint. If there's any missing, touch up is required to keep
that sacrificial layer intact. " Keeping up with inspection intervals
and preventative maintenance will prolong the life of the aircraft
and keep it operating safely, " explained Hayes. " Once corrosion
appears, it's paramount to keep it from propagating. Removing as
much of the corrosion as possible while still maintaining structural
integrity is key. After the corrosion has been removed, treating the
area with an appropriate corrosion preventative is necessary to
keep the corrosion from spreading. "
AIRCRAFT MAINTENANCE TECHNOLOGY
AMT_June-July_2021

Table of Contents for the Digital Edition of AMT_June-July_2021
