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a) The aft static ports (S2) on the lower left pitot-static probe b) The forward static ports (S1) on the upperleft pitot-static probe c) The left alternate static port. 5) Connect pitot (vacuum) source in pneumatic test unit through a pitot control valve to a pitot cutoff valve.
6) Using two pitot system pitot-static probe adapters, connect pitot inlets of upper left and upper right pitot-static probes to pitot cutoff valve through pitot system test gage and a flow restrictor.
7) Seal the pitot chamber drain holes in upper left and upper right pitot-static probes with vinyl adhesive tape.
(b) Test captain's, first officer's and alternate static systems for leakage. 1) Make sure test equipment installation is complete and
ready for operation. 2) Open pitot cutoff valve and three static cutoff valves.
CAUTION: TO PREVENT INSTRUMENT/EQUIPMENT DAMAGE, KEEP
_______ RATE OF STATIC PRESSURE CHANGE BELOW 3000 FEET PER MINUTE AND DIFFERENTIAL PRESSURE BETWEEN 0 AND 10 INCHES OF MERCURY.
3) As the next step is performed, operate pitot vacuum source and control valve such that pressure in pitot system does not start to decrease until after static system has begun to evacuate. After pitot system falls to 20 inches of mercury (absolute) or below, close pitot control and cutoff valves. Allow static system to continue being pumped down to required level. Pitot system vacuum should be monitored continuously during pump down to ensure compliance with above caution note.
4) Operate pneumatic test unit and static control valve to apply a vacuum equivalent to 11.10 (| 0.10) inches of mercury (absolute pressure) or 25,000 (| 200) feet of altitude to three static systems as indicated on captain's and first officer's altitude indicators and on all three static system test gages.
5) When required vacuum has been reached and has stabilized in both pitot and static systems, close all four cutoff valves.
CAUTION: VACUUM MUST BE HELD AS A BACKUP BEHIND CUTOFF
_______ VALVES DURING CUTOFF PERIOD. FOLLOWING THIS, CUTOFF VALVES ARE REOPENED. RELEASE OF VACUUM IS GRADUAL AND SIMULTANEOUS FOR ALL PITOT AND STATIC SYSTEMS.
EFFECTIVITY
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6) Immediately after closing cutoff valve, read and record indication on each of three static system gages.
NOTE: Accuracy of reading and recording vacuum pressure
____ or altimeter must be | 0.01 inch of mercury or | 20 feet of altitude respectively.
7) After 1 minute, read and record values indicated on three static system gages. Vacuum must not have decreased by more than 0.20 inch of mercury or an equivalent fall of 400 feet in indicated altitude.
8) Release vacuum on both static and pitot systems.
9) Remove all adapters and vinyl adhesive tape from pitot-static probes. Close static cutoff valves that supplied vacuum to upper and lower right pitot static probes.
WARNING: FAILURE TO REMOVE VINYL ADHESIVE TAPE FROM STATIC
_______ PORTS BEFORE FLIGHT MAY CAUSE LARGE ERRORS IN AIRSPEED-SENSING AND ALTITUDE-SENSING SIGNALS, WHICH MAY LEAD TO LOSS OF SAFE FLIGHT.
CAUTION: TO PREVENT PITOT-STATIC PROBE DAMAGE, VISUALLY
_______
CHECK EACH PROBE AND VERIFY NO PIECES OF COLORED
TAPE REMAIN ON PROBE.
10) Operate pneumatic test unit and static control valve to apply a vacuum equivalent to 11.10 (| 0.10) inches of mercury (absolute pressure) or 25,000 (| 200) feet of altitude to alternate static system as indicated on static system test gage.
11) After system has stabilized, close last static cutoff valve and immediately read and record indication on static system gage.
NOTE: Accuracy of reading and recording vacuum pressure
____ or equivalent altitude must be | 0.01 inch of mercury or | 20 feet of altitude respectively.
12) After 1 minute, read and record value indicated on static system gage. Vacuum must not have decreased by more than
0.20 inch of mercury or an equivalent fall of 400 feet in
indicated altitude. 13) Release vacuum on alternate static system.
EFFECTIVITY
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14) Remove adapter and vinyl adhesive tape from right and left alternate static ports respectively and close static cutoff valve.
WARNING: FAILURE TO REMOVE VINYL ADHESIVE TAPE FROM STATIC
_______ PORTS BEFORE FLIGHT MAY CAUSE LARGE ERRORS IN AIRSPEED-SENSING AND ALTITUDE-SENSING SIGNALS, WHICH MAY LEAD TO LOSS OF SAFE FLIGHT.
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