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PRIMARY ALTITUDE INDICATOR - ADJUSTMENT/TEST
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1. Primary Altitude Indicator Test
_______________________________
A. General
(1) This test verifies proper installation of the primary altitude indicator and is valid for either the captain's or first officer's indicator.
B. Referenced Procedures
(1) 24-22-00, Maintenance Practices (Apply Power)
C. Equipment and Materials
(1)
Pneumatic test unit
(2)
Pitot-Static System Probe Adapter - T856-660, or equivalent
D. Prepare for Test
(1)
Check that static source select valve is in NORMAL position.
(2)
Place mode switch on altitude indicator in STBY position, if applicable.
(3)
Wet pitot-static probe adapter and install on upper left pitot-static probe to check captain's indicator or on upper right probe to check first officer's indicator.
CAUTION: ENSURE THAT PROBE ADAPTER IS FLUSHED WITH WATER OR OXY-
_______ TECH BEFORE INSTALLING OR ADAPTER MAY BE DAMAGED. A SOLUTION CONSISTING OF HALF PURE ETHYLENE GLYCOL AND HALF WATER SHOULD BE USED IN FREEZING TEMPERATURES DOWN TO -40.F. TO PREVENT PROBE MISALIGNMENT, TEST HOSES AND ADAPTERS MUST BE SUPPORTED IN SUCH A WAY AS TO ADD NO EXTRA WEIGHT ON PROBE.
(4)
Temporarily seal static port S2 on lower right auxiliary pitot-static probe to check captain's indicator or static port S2 on lower left auxiliary probe to check first officer's indicator.
(5)
Connect static (vacuum) source in pneumatic test unit through the static control and cutoff valves to static port Sl on probe adapter.
E. Test Primary Altitude Indicator
(1) Operate pneumatic test unit and static control valve to apply a vacuum equivalent to the ambient pressure minus 5.25 (|0.25) inches Hg or 5000 feet above airport altitude as indicated on captain's or first officer's indicator and on test gages.
CAUTION: RATE OF APPLICATION OR RELEASE OF VACUUM MUST BE
_______ EQUIVALENT TO A CLIMB OR DESCENT RATE OF LESS THAN 3000 FEET PER MINUTE.
(2)
When required vacuum has been reached and has stabilized in static system, close cutoff valve. Read and record immediately, indication on test gages. Accuracy of reading must be | 0.01 inches of mercury or | 20 feet of altitude.
(3)
After 1 minute, read and record indication on test gages. Vacuum must not have decreased by more than 0.07 inch Hg or an equivalent decrease of 80 feet in indicated altitude.
EFFECTIVITY
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(4) Release vacuum on static system, observing caution in step (1) above
(5) Remove adapter and seals from pitot-static probes and secure test unit. CAUTION:_______VISUALLY CHECK EACH PROBE AND VERIFY THAT NO COLORED TAPE REMAINS ON THE PROBES.
(6)
Check that panel light circuit breakers on panel P6 are closed.
(7)
Provide electrical power (Ref 24-22-00).
(8)
Check that indicator illumination lights are on.
(9)
Remove electrical power if no longer required (Ref 24-22-00).
EFFECTIVITY
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INDICATED AIRSPEED INDICATOR - REMOVAL/INSTALLATION
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1. Referenced Procedures
_____________________
A. 24-22-00, Maintenance Practices (Apply Power)
B. 34-11-00, Adjustment/Test
2. Remove Indicated Airspeed Indicator
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A. On panel P7, open circuit breakers CADC 1, CADC 1 SYNC EXCIT, CADC 1 -IAS/MACH IND 1 and AUTO THROT AC (for captain's indicator) or CADC 2, CADC 2 SYNC EXCIT, CADC 2 - IAS/MACH IND 2 and AUTO THROT AC (for first officer's indicator).
B. Loosen instrument mounting clamp and slide indicator out of instrument panel.
CAUTION: DRAW INDICATOR OUT OF INSTRUMENT PANEL WITH CARE TO AVOID
_______ STRESS AND/OR DAMAGE TO CABLE AND PNEUMATIC HOSES AT BACK OF CASE. TO AVOID INSTRUMENT DAMAGE, PITOT AND STATIC SYSTEM PRESSURES MUST BE AT AMBIENT BEFORE PROCEEDING.
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