D. Test Pitot Systems
(1) Test captain's pitot system for leakage, observing the cautions in steps A.(3) and A.(4) above.
NOTE: Accuracy of reading and recording pressure should be + 0.03 inches of mercury or + 1 knot.
(a)
Temporarily seal pressure chamber drain hole in captain's pitot static probe (upper left probe). Connect air pressure supply to pitot static probe (pitot pressure portion).
(b)
For low-range leakage test: 1) Apply pressure of 250 knots on captain's airspeed/mach indicator or test indicator.
2) After system has stabilized, cut off pressure between airplane system and pressure source. Read and record airspeed/mach indicator or test indicator reading.
3) Wait 1 minute. Check that pressure does not decrease more than 2.5 knots.
(c) For full-range leakage test: 1) Apply pressure of 4.53 (+ 0.16) inches of mercury (gage) or 300 (+ 5) knots on captain's airspeed/mach indicator or pressure indicator. 2) After system has stabilized, cut off pressure between airplane system and pressure source. Read and record airspeed/mach indicator or test indicator.
3) Wait 1 minute. Pressure should not decrease more than 0.16 inches of mercury or 5 knots of airspeed.
(2)
Test first officer's pitot system for leakage.
(a) Repeat steps D.(l)(a) through (c) above on the upper right pitot static probe.
(3)
Test auxiliary No. 1 or No. 2 pitot system for leakage.
(a) Repeat steps D.(l)(a) through (c) on lower right probe (No. 1 system) or lower left probe (No. 2 system).
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E. Test Static Systems
(1)
Temporarily seal all static ports to which test adapters have not been applied. Method of sealing should not extend into static ports or deform or alter surface in the area when seals are removed.
(2)
Place captain's and first officer's static source selector valves in NORMAL position.
CAUTION: PITOT PRESSURE SHOULD ALWAYS EQUAL OR EXCEED STATIC LINE PRESSURE AND DIFFERENCE (DIFFERENTIAL PRESSURE) SHOULD NOT EXCEED 10.00 INCHES OF MERCURY. DIFFERENTIAL PRESSURE DESCRIBED ABOVE SHOULD NOT FALL BELOW ZERO.
NOTE: Accuracy of reading and recording vacuum pressure or altimeter should be +
0.01 inches of mercury or + 20 feet of altitude respectively.
(3) Test captain's static system for leakage observing cautions in steps A.(3) through A.(6).
(a)
Place all static cutoff valves in open position.
(b)
Apply a vacuum to captain's static system on lower right probe (preferred) or drain fitting No. 11 (connection not shown in figure 501).
(c)
For low-range leakage test: 1) Apply a vacuum to the system, so that captain's altimeter indicates an altitude of 3000 feet. 2) After system has stabilized, shut off vacuum using appropriate static cutoff
valve. Read and record altimeter or test indicator reading. 3) Wait 1 minute. Check that vacuum does not decrease more than 60 feet.
(d)
For full-range leakage test:
1) Apply a vacuum equivalent to 12.37 (+ 0.10) inches of mercury (absolute pressure) so that captain's altimeter indicates 22,500 (+ 200) feet. Pitot system should also be evacuated, if necessary, to meet the requirement under the caution note.
2) After system has stabilized, shut off vacuum using appropriate static cutoff valve. Read and record altimeter or pressure indicator reading.
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3) Wait 1 minute. Vacuum should not decrease more than 0.21 inches of mercury or 400 feet in altitude.
CAUTION: VACUUM SHOULD BE HELD AS A BACKUP BEHIND CUTOFF VALVE DURING CUTOFF PERIOD. FOLLOWING THIS PERIOD, CUTOFF VALVE SHOULD BE REOPENED. RELEASE OF VACUUM SHOULD BE GRADUAL AND SIMULTANEOUS FOR ALL STATIC SYSTEMS.
(4)
Test first officer's static system for leakage.
(a)
Place shutoff valve in open position.
(b)
Apply a vacuum to first officer's static system on upper right probe (preferred) or drain fitting No. 9.
(c)
Repeat steps E.(3)(c) and (d) above for first officer's static system and altimeter.
(5)
Test auxiliary No. 1 static system for leakage.
(a)
Place shutoff valve in open position.
(b)
Apply a vacuum to auxiliary No. 1 static system on lower right probe (preferred) or drain fitting No. 12.
(c)
Repeat steps E.(3)(c) and (d) above using pressure indicator or altimeter.
