First
there has to be said that it’s not possible to give a short
and 100% correct answer. It
varies a lot depending on the statement from the manufacturer
of the aircraft to the manufacturer of the hose assembly or the
manufacturer of the engine. As a guidance we are able to say following:
Rubber
hose assemblies
The
manufacturer of the aircraft is responsible for making life
limitations on hose assemblies. In practice this interval is
between 5 and 10 years, most times depending on the different
manufacturers. If the manufacturer made no limitation or maybe
the manufacturer doesn’t exist any more (a well known problem in Germany),
ask your local aviation authority. For example the German LBA made
clear that any hose assembly that is not specified with it’s
lifetime and also not with a concrete inspection instruction,
has to be overhauled every 5 years.
PTFE
hose assemblies
“On
Condition” is
a well known argument for the lifetime of PFTE hoses. As
a remark, some manufacturer also demand the replacement of PFTE
hoses for special applications.
What
we can tell you for sure are criterions for damaged hose assemblies.
Criterions for the hose inspection
- Inspect hoses frequently
- Replace worn or damaged hoses
- Proper clamping is critical
Hose
assemblies have to be replaced if following is applicable
- Chafed Hose
- Abrasion
- Improper clamping
- Kinked Hose
- Smooth-bore PTFE hose is prone to kinking
- Restricts fluid flow
- Damaged beyond repair
- Broken Wires
- Inspect external wire braid
- Any broken wires is cause for removal/scrap
- Twisted Hose
- Hose is not designed to be twisted
- Induces stress
- Promotes premature wear
- Heat Damaged (Brittle) Hose
- Elastomeric, PTFE and Metal Hose have heat limitations
- Cracks during flexing
- Leaking Hose
- Wetness around fitting
- Aged hose
- Improper fitting attachment
- Rusted Hose
- Corroded
wire braids
- Any
corrosion makes hose assembly suspect
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