Prior to installation, all field-fabricated hose assemblies must be
pressure tested; factory or depot lubricated assemblies must be
pressure tested regardless of whether they were tested at the time of
During installation, care must be taken to ensure the line is not
twisted or bent to exceed limitations. Hose must be supported along
its length at intervals of 24 inches or less, depending on the size
of the hose.
The swiveling parts and mating surfaces of hose assemblies must be
lubricated before installation to ensure effective seating of the
component parts. Self-sealing hose must never be lubricated.
Aircraft hose and rubber
components must be stored in a dark, cool,
dry place protected from
exposure to strong air currents and dirt.
Neither Teflon nor rubber
hose is limited in its shelf life; however,
prior to installation all
hose assemblies and seals must be inspected
to ensure serviceability.
PART C - SEALS AND GASKETS
Seals and gaskets are used throughout aircraft plumbing systems to
prevent leaks when two components are joined together. The material
from which the seals are manufactured varies depending upon the fluid
or gas being conducted and the operating pressure range of the
Using the proper type of seal and exercising care during
installation are two of the most important phases of plumbing
maintenance. Lack of care during this phase of maintenance is one of
the most frequent causes of system failure or leaks.
In this part,
the types of seals and gaskets used in aircraft plumbing systems are
discussed; and their capabilities, advantages, limitations, and
installation procedures are presented.
The seals or packings used in hydraulic systems are manufactured from
rubber, leather, teflon, metal, or a combination of any of these.
Two types of rubber, natural and synthetic, are used for making
hydraulic seals; however, only synthetic rubber seals can