(2)
Any application or release of pressure to a pitot system must be made such that the equivalent rate of change in airspeed is less than 300 knots per minute. (Use appropriate gage saver restrictions.)
(3)
Absolute pressure in the pitot systems must never be less than the pressure in the static systems. The difference between pitot and static system pressures must never exceed 10 inches of mercury.
(4)
The absolute pressure applied to any static system must never exceed the ambient pressure when any airspeed instrument is connected to that static system nor exceed 31 inches of mercury.
(5)
The captain's, first officer's and alternate static systems must be exposed to the same absolute pressure conditions simultaneously during any leakage test except as specified.
(6)
Pitot-static probe heaters must be off during tests. Place DO NOT OPERATE signs on both probe heater switches (Ref 30-31-00).
(7)
Pitot lines must be disconnected during full range test of No. 1 and No. 2 auxiliary pitot-static systems, or elevator feel computers and stabilizer control modules could be damaged.
B. Equipment and Materials
(1)
Pneumatic Test Unit
(a)
Dry air pressure source (1 required), 30 to 35 inches of mercury (absolute)
(b)
Vacuum sources (2 required), 10 to 30 inches of mercury (absolute)
(2)
Adapters
EFFECTIVITY
ALL 09 Page 501 Apr 25/9334-11-00
PITOT
VALVE
Pitot-Static Systems - Test Equipment Connection
Figure 501
EFFECTIVITY ALL
751 Page 502
34-11-00
Oct 25/96
(a)
One flush static port adapter for alternate static system (surface contact only, must not make metallic contact with port) - F72823-23 or -40.
(b)
Two pitot-static system probe adapters - 884EE with RCF kit P/N 508 or; RCF Seals & Couplings, Inc., P/N 508747.
(c)
Pitot-static probe adaptor - NAVAIDS, P/N PSS44600M-3-4-4.
(3)
Gages (Fig. 502)
(a)
Pitot system test gage - required to indicate: 1) Pressure of 30 to 35 inches of mercury (absolute) with accuracy of | 0.16 (readable to | 0.03) inch of mercury or | 5 (readable to | 1) knots and 2) Vacuum of 10 to 30 inches of mercury (absolute) with accuracy of | 1 inch of mercury minimum
(b)
Static system test gage - required to indicate vacuum of 10 to 30 inches of mercury (absolute) with accuracy of | 0.1 (readable to | 0.01) inch of mercury or | 200 (readable to | 20) feet
(c)
Rate-of-climb indicator - indicating range of 0 to | 6000 feet/minute
(d)
Differential pressure gage - required to indicate 10 inches of mercury differential pressure (minimum) with an accuracy of | 0.010 inch of mercury
(4)
Flow restrictors, control valves, cutoff valves, lines and port seals as required
(5)
G02321, Vinyl Adhesive Tape
C. Referenced Procedures
(1)
21-33-05, Removal/Installation
(2)
29-11-00, Maintenance Practices
(3)
31-31-01, Servicing
D. Low Range Leakage Test - Pitot-Static System
(1) Prepare for Test
(a)
Ensure that autopilot remains off during this test.
(b)
Set both static source selector valves to NORMAL position. They will remain in this position throughout the test.
(c)
Ensure that pitot-static probe heaters remain off during this test.
(d)
See that flow restrictors are always placed between cutoff valves and airplane pitot and static systems.
CAUTION: PITOT-STATIC PROBES ARE DELICATE INSTRUMENTS AND
_______ CRITICALLY ALIGNED ON THE AIRPLANE. EXTREME CARE MUST BE EXERCISED WHEN INSTALLING, REMOVING OR HANDLING.
(2) Test Pitot Systems
(a) Connect test equipment as follows (Fig. 501):
1) Connect pitot (pressure) source in pneumatic test unit through pitot control valve to pitot cutoff valve.
EFFECTIVITY
ALL 27 Page 503 Oct 25/9734-11-00
| ACCURACY TOLERANCE RANGE
| INCHES HG | ALTITUDE (FT) | AIRSPEED (KTS)
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