56-101-00184
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00185 Rev. I
CH. 4
September 24, 2014
Page 31 of 56
CHAPTER 4. VALVE LEAK TEST
1. METERING VALVE ADJUSTMENT PROCEDURE
Note: The following procedure is also released as IM150 (dated 7/6/88.)
A. Valve Leak Test
Caution: Before performing the Valve Leak test, inspect for system or instrument
leakage. (Refer to the appropriate Aircraft Maintenance Manual for
information and proper procedure.)
Note: Read sections “A” and “B” before performing test since steps listed in sections
must be done in combination when performing valve adjustments.
B. Pressure Valve Test
(1) Close all valves except "VACUUM VENT".
(2) Plug "PRESSURE" and "VACUUM PORTS". (Single action pumps only.)
(3) Pressurize "PRESSURE TANK" to 15 psi.
(4) Monitor AIRSPEED INDICATOR for one (1) minute.
(5) If there is an increase in airspeed seen, continue to monitor for an additional five
(5) minutes.
Note:
If during the monitoring period the increase exceeds five (5) knots, a leak
exists at the "PRESSURE" valve.
(6) Correct leak before continuing (Refer to this section 2. RESETTING
NEEDLE
VALVE POSITIVE STOP).
C. Pressure Vent and Crossbleed Valve Test
(1) Close all valves except "VACUUM VENT".
(2) For single action pumps, plug the "PRESSURE" and "VACUUM " ports.
Caution: Do not over pressurize airspeed.
(3) Apply enough pressure to the "PRESSURE TANK" to provide FULL SCALE
AIRSPEED INDICATOR TRAVEL.
(4) Gently open the "PRESSURE" valve. Increase the airspeed to FULL SCALE.
(5) Close "PRESSURE" valve.
(6) Monitor the AIRSPEED INDICATOR for one (1) minute.
Note:
If there is a decrease of more than two (2) knots, a leak exists at the
"PRESSURE VENT" or "CROSSBLEED" valve.
