Piper SARATOGA PA-32-301 Maintenance Manual page 97

PIPER AIRCRAFT
PA-32-301/301T
MAINTENANCE MANUAL
IDENTIFICATION OF FLUID LINES. (Refer to Figure 20-4.)
Fluid lines in aircraft are often identified by markers made up of color codes, words, and geometric
symbols. These markers identify each line's function, content, and primary hazard, as well as the direction of
fluid flow.
In most instances, fluid lines are marked with 1 inch tape or decals. Paint is used on lines in engine
compartments, where there is the possibility of tapes, decals or tags being drawn into the engine induction
system.
In addition to the above-mentioned markings, certain lines may be further identified as to specific
function within a system; for example, DRAIN, VENT, PRESSURE or RETURN.
Lines conveying fuel may be marked FLAM; lines containing toxic materials are marked TOXIC in place
of FLAM. Lines containing physically dangerous materials, such as oxygen, nitrogen, or freon, are marked
PHDAN.
The aircraft and engine manufacturers are responsible for the original installation of identification
markers, but the aviation mechanic is responsible for their replacement when it becomes necessary.
Generally, tapes and decals are placed on both ends of a line and at least once in each compartment
through which the line runs. In addition, identification markers are placed immediately adjacent to each valve.
regulator, filter or other accessory within a line. Where paint or tags are used, location requirements are the
same as for tapes and decals.
INSTALLATION OF FLEXIBLE HOSE ASSEMBLIES.
1. Flexible hose must not be twisted on installation.
Flexible hose which is installed with a twist may have a reduced service life and may cause a loosening of
the fittings to which it is attached.
2. Never exceed the minimum bend radius and avoid tight bends in flexible hose assemblies. (Refer to
AC43:13-1, Chapter 10.)
3. Never stretch a hose tight between two fittings as this may result in overstressing and eventual failure.
The length of the hose should be sufficiently long to provide 5 to 8 percent slack.
FLARELESS TUBE ASSEMBLIES. (Refer to Figure 20-5.)
Although the use of flareless tube fittings eliminates all tube flaring, another operation, referred to as
presetting, is necessary prior to installation of a new flareless tube assembly which is performed as follows:
1. Cut the tube to correct length, with the ends perfectly square. Deburr the inside and outside of the
tube. Slip the nut, then the sleeve, over the tube (Step 1).
2. Lubricate the threads of the fitting and nut. See Figure 20-5 for proper lubricant to use, depending on
the type system the tubing assemblies are to be used on. Place the fitting in the vise (Step 2), and hold the tubing
firmly and squarely on the seat in the fitting. (Tube must bottom firmly in the fitting.) Tighten the nut until the
cutting edge of the sleeve grips the tube. This point is determined by slowly turning the tube back and forth
while tightening the nut. When the tube no longer turns, the nut is ready for final tightening.
3. Final tightening depends upon the tubing. For aluminum alloy tubing up to and including 1 2 inch
outside diameter, tighten the nut from one to one and one-sixth turns. For steel tubing and aluminum alloy
tubing over 1, 2 outside diameter, tighten from one and one-sixth to one and one half turns.
After presetting the sleeve, disconnect the tubing from the fitting and check the following points
(illustrated in Step 3):
1. The tube should extend 3/32 to 1/8 inch beyond the sleeve pilot; otherwise blowoff may occur.
2. The sleeve pilot should contact the tube or have a maximum clearance of 0.005 inch for aluminum
alloy tubing or 0.015 inch for steel tubing.
3. A slight collapse of the tube at the sleeve cut is permissible. No movement of the sleeve pilot, except
rotation is permissible.
20-06-00
Page 20-04
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Revised: August 11, 1983
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