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Instruments and Instrument System Maintenance. | Up
TM-1-1500-204-23-4 General Aircraft Maintenance (Electrical and Instrument Maintenance Procedures) Volume 4 Manual | Next
Figure 4-10. Pitot Tube |
TM 1-1500-204-23-4
method, and the solid color band, the alternate method.
Identification tapes will be applied to plumbing lines and
electrical conduits of all Army aircraft.
(a) Printed-symbolized tape system. This
latest and preferred system utilizes printed colored tape
(1 inch wide) with geometrical symbols. The main
function of the line is printed on the tape.
(b) Solid color band system. This alternate
system consists of the use of one, two, or three bands of
1/2-inch wide solid colored tape wrapped on various
lines for identification. .
c. Pitot Static System. The pitot static system, as
shown in figure 4-7, consists of pitot-static tubes or pitot
tubes with static pressure ports or vents and their related
heaters, if any, and includes lines, tubing, water drains
and traps, and selector valves. Pressure actuated
indicators such as the altimeter, airspeed, and rate-of-
climb indicators, and control units such as air data
transducers, and automatic pilots may be connected to
the system.
(1) Principles of operation. Ram pressure
enters the pressure line through an opening at the
forward end of pitot tube and passes through the
pressure line to the airspeed indicator. Static pressure
is passed through the static pressure line to the vertical
velocity indicator, altimeter, and airspeed indicator static
pressure connections.
(2) Inspection of System. Inspect air
passages in the systems for water, paint, dirt or other
foreign matter. Remove obstructions in accordance with
applicable maintenance manual.
(a) Required equipment. A pitot static
system tester, as shown in figures 4-8 and 4-9, is
needed to complete pitot static system tests.
(b) Pitot line leak test procedures.
Pitot line leak test connections are shown in figure 4-8.
Do tests using the procedures that follow:
1
Seal pitot tube drain holes air
tight with pressure sensitive tape, Federal Specification
A-A-883.
CAUTION
Do not apply suction to pitot lines
or
pressure
to
static
lines.
Damage to bellows, indicators,
and computer equipment may
occur.
(3) System Leak Testing. Pitot-static leak
tests should be made with all instruments connected to
assure that no leaks occur at instrument connections.
Such tests should be made whenever a connection has
been loosened or an instrument replaced. Pitot systems
should be tested in accordance with the aircraft
manufacturer's instructions. If the manufacturer has not
issued instructions for testing pitot systems, the
following may be used:
Figure 4-7. Pitot Static System
4-10
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