MACH AIRSPEED WARNING SYSTEM - ADJUSTMENT/TEST
EFFECTIVITY
GJ ALL EXCEPT B-2509 thru B-2510 and B-2524
1. Mach Airspeed Warning System Test
A. Equipment and Materials
(1)
Air pressure and vacuum source, 5-40 inches of mercury absolute, with adapters for connection to pitot and static sources on pitot static tube or to test fittings.
(2)
Gage for measuring differential pressure accurate within . .010 inches of mercury with a range of at least 10 inches of mercury.
B. Prepare to Test Mach Airspeed Warning System
(1)
When applying pitot pressure, note following:
(a)
Pitot static tube heaters should remain OFF during these tests.
(b)
Pitot line pressure over static line pressure should not exceed 9 inches of mercury. Static line pressure must never exceed pitot line pressure.
(2)
When applying static pressure, note following:
CAUTION: CABIN ALTITUDE DIFFERENTIAL PRESSURE INDICATOR SHOULD BE DISCONNECTED FROM ITS STATIC PRESSURE SOURCE AND SOURCE SHOULD BE CAPPED.
(a)
Static source selector valves should be in NORMAL position and should not be changed while vacuum is on static system.
(b)
Do not apply pressure in excess of 31 inches of mercury absolute to static lines.
(c)
Apply or release vacuum at a rate of climb or descent of approximately 3000 feet per minute or less between test points. At each test point pressure should be reduced slowly to desired level without overshoot.
(d)
Seal static port on pitot static probe surface in such a way that removal of seal will be complete, leaving no deposits or roughness in or about static ports.
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(e)
Apply pressure to system using pitot static probes by performing steps (f) through (h) or using system drain fittings by performing steps (i) thru (l).
(f)
Connect vacuum source with adapter to No. 1 auxiliary static port on lower right pitot static probe.
(g)
Seal No. 1 auxiliary static port on upper left pitot static probe.
(h)
Connect positive pressure source with adapter to No. 1 auxiliary pitot port on lower right pitot static probe.
(i)
Connect vacuum source with adapter to No. 4 drain fitting located on the right side E1 electronics rack.
(j)
Seal No. 1 auxiliary static port on lower right and upper left pitot static probes.
(k)
Connect positive pressure source with adapter to No. 3 drain fitting located on right side of E1 electronics rack.
(l)
Seal No. 1 auxiliary pitot tube port on lower right pitot static probe.
(m)
Connect differential pressure gage into pitot and static test lines.
(n)
Disconnect cabin differential pressure indicator and cap static pressure tube.
C. Test Mach Airspeed Warning Systems
WARNING: WARNING DEVICE (CLACKER) SHOULD NOT BE ENERGIZED FOR MORE THAN 5 MINUTES OR DAMAGE MAY RESULT. ALLOW A MINIMUM COOLING PERIOD OF 15 MINUTES BEFORE ENERGIZING SYSTEM AGAIN.
(1)
Close MACH WARN circuit breaker. Push MACH AIRSPEED WARNING TEST switch located on flight recorder and mach airspeed warning test module (P5 overhead panel). Clackers should come on.
(2)
Release test switch. Clackers should go off.
(3)
Apply pressure as shown in Table I. Clackers should come on within tolerances indicated and go off when differential pressure is reduced below lower tolerance value.
CAUTION: DIFFERENTIAL PRESSURE SHOULD BE BETWEEN 0 AND 10 INCHES OF MERCURY AT ALL TIMES.
(4)
Release vacuum at specified rate. TABLE 1
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ALT (FEET) (REF) STATIC PRESSURE IN HG ABSOLUTE PITOT PRESSURE IN HG ABSOLUTE DIFF PRESSURE IN HG ABSOLUTE INDICATED AIRSPEED KNOTS
Sea Level 20,000 30,000 35,000 29.921 13.750 8.885 7.041 36.207-36.441 20.562-20.806 14.104-14.252 11.173-11.295 6.286-6.520 6.812-7.056 5.219-5.367 4.132-4.254 350.0-356.0 363.4-369.4 320.7-324.9 287.0-291.0
D. Restore Airplane to Normal Configuration
(1)
Restore mach airspeed warning and pitot static systems to normal.
(2)
If no longer required, remove electrical power from airplane.
Feb 20/93 34-15-0 Page 503
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
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