November/December 2023 - 33

and usage, affirms Bill Lesser, global aviation manager
of Hewitt, A Husky Company. " If the hose is in
constant use and not removed from service, it can
last anywhere from six months at major airports
to 10 years at the smallest facilities, " he said. " It is
the responsibility of the user to conduct at least
monthly inspections of hose assemblies for wear, as
well as any movement of the fittings on the end of
the hoses. In addition, pressure testing of an assembly
to a minimum of working pressure should be
conducted at least every six months. "
Time to Inspect
Kerkman said aviation ground fueling hoses are
checked routinely - daily, monthly, and during preventive
maintenance of the equipment the hose is
installed on. " Also, all fueling hoses have to meet
the requirements of the EI 1529, Type C standards
or those of EI 1529 Grade 2 Type CT standards for
cold temperature hoses, " he said.
According to Lesser, one should immediately discard
the hose assembly if it is more than 10 years old,
if it indicates general signs of wear, or if it was stored
for more than two years. " The aviation ground fueling
hose assembly should also be discarded if it is
put into service, then removed and not rotated back
into service within 15 days, if it shows any movement
of the permanent fittings on the end of the
hose, or if it is in service with a hose cover that has
cracks, nicks, and/or gouges in which the braid or
spiral wraps are visible, " he said.
In general, affirms Parsons, any exposed airborne
hoses should be inspected during the aircraft walk
around prior to every flight. " Naturally, exposed
hoses experience some wear and tear a little more
quickly, due to environmental factors and hoses
within the aircraft body should be inspected during
regularly scheduled maintenance checks of
the other aircraft systems, " she said. " Ultimately,
the user is responsible for making the decision
of when to replace the hose and should use their
own analysis, testing and review of maintenance
records and data. It is important that the user diligently
ensures all performance, safety and warning
requirements of the application are properly followed.
The SAE Aerospace Committee's inspection
guide for installed hose assemblies was designed
to help in that determination process. "
On commercial aircraft, polytetrafluoroethylene
(PTFE) hoses are normally used, while aircraft rubber
hoses are more common on smaller aircraft,
explains Parsons. " This is because while PTFE hoses
are more expensive, they are generally preferred over
other hose types since they are extremely robust
and built for extreme environments experienced
on commercial aircraft, " she said. " Capabilities for
the PTFE hose might include vibration loading,
chemical resistance, and temperature extremes,
which is why they can be used on multiple systems
throughout the aircraft. Once installed, they rarely
need to be replaced, unless damaged. "
Repair or Replacement
There are few options to repair aviation ground fueling
hoses in the field, affirms Lesser. " If a fitting is
damaged, one can send the hose back to an aviation
hose company like Hewitt for the fitting to be
removed and a new fitting to be attached, inspected,
pressure tested, checked for continuity and a new
certificate is issued, " he says. " Outside of the US, one
can make use of reusable couplings to repair damage
couplings or, if one wants to shorten the hose,
this can be done in the field by a qualified person
with knowledge of how to assemble the reusable
couplings to the hose. The assembled hose does need
to be tested for pressure and continuity prior to use. "
In case of damage to aviation ground fueling
hoses, these can be sent back to approved facilities
to perform a pressure test and more thorough
inspection of the hose to see if the hose can be recoupled
or if a replacement hose is required, according
to Kerkman. " Typically, for maintaining equipment
uptime, hose replacements are more prevalent than
having a hose sent in for inspection or repair. In the
US, as the hoses are typically coupled with nonrepairable
ends, there is no 'in the field' repair option
for hose coupling ends, " he said.
According to Parsons, due to airborne hose construction,
damaged hoses should be replaced, not
repaired. " Unlike rigid tube assemblies, hose assemblies
are made up of layers of different material
and unique structural components, which may be
bonded to each other, with end fittings permanently
attached in many cases. If there is even a minor
indication of damage to a hose, such as kinking,
the hose needs to be proactively replaced, " she said.
" In the short term, if a minor abrasion is seen, an
additional abrasion sleeve can be put on a hose as
chafe protection. As always, the application and
operating condition matter when evaluating this
type of repair, which is not a long-term option for
safety and reliability reasons. "
www.AviationPros.com 33
http://www.AviationPros.com
November/December 2023

Table of Contents for the Digital Edition of November/December 2023
