Drycleaning solvent is flammable and solvent vapors are toxic. Use P-D-680, Type II Solvent In a well-
ventilated area. Keep away from open flames. Avoid prolonged solvent contact with skin.
After proof test of a hose assembly using hydraulic fluid or oil as a test medium, flush or dip
assembly in kerosene, Federal Specification VV-K-211, or solvent, Federal Specification P-D-680. Drain assembly and
dry using by compressed air. Those assemblies tested with water as the pressure fluid will be drained and dried with dry
Install the following polyethylene protective plugs in end fittings of hose assemblies that are not
to be immediately installed after fabrication. NAS 815(*size) (*same dash number as fitting). Close openings in flanges
(or other special fittings) using pressure sensitive tape or other adequate means to prevent entrance of foreign material.
Use of Dust Plugs, Dust Caps, and Moisture Seals. The following paragraphs provide instructions for use of
plugs, caps, and seals.
Sealing with plugs, caps, and seals. Dust plugs, dust caps, and moisture seals shall be used to
provide proper closures to prevent leakage and contamination of aircraft systems when lines or units are disconnected
for maintenance, repair, shipping, storage, and bulk material in free stock. See figures 4-51 through 4-56 for types of
dust plugs, dust caps, and moisture seals. These plugs and seals are of plastic (polyethylene), aluminum, steel
(cadmium or zinc plates), rubber, and synthetic rubber. They will not scale or chip and require no tools for installation,
hand tightening being sufficient to provide proper protection. After removal, plugs and seals shall be thoroughly cleaned
and sorted for reuse.
Plugs or seals shall not be used under operating pressures.
Alternate sealing methods. Exposure to high temperature and dust conditions, such as in desert
climates, cause plastic and rubber closures to shrink, deteriorate, and become difficult or Impractical to use. Heavy
aluminum foil may be used to protect plugs and seals from deterioration and prevent dirt and sand from entering tubing,
connectors, and threaded fittings, especially on equipment stored outside. Heavy aluminum foil may also be used to
protect open lines, connections, quick disconnect couplings, etc.,. when standard AN-SAE threaded closures are not
available. Recommended aluminum foil thickness is from 0.003 to 0.005 Inch, and can be locally procured or
requisitioned from Federal Stock Class 9535.
Prior to connection on any lines where aluminum foil has been used with standard AN-SAE threaded
closures, a thorough Inspection will be made to ensure that no foil has entered lines. Any conflict between
this manual and the manual for a particular aircraft or other item of equipment concerning use of
aluminum foil will void Instruction in paragraph (2).
Change 2 4-74.1