(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.
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MACH AIRSPEED WARNING SYSTEM - DESCRIPTION AND OPERATION
EFFECTIVITY
GJ B-2509 thru B-2510 and B-2524
1. General (Fig. 1)
A. The mach airspeed warning system is provided to alert the flight crew when the airplane approaches a critical speed. The warning is accomplished by the mach airspeed indicators and an aural warning. Two complete systems are installed on the airplane; and the theory of operation for both systems is identical. A push-to-test switch is provided on the overhead panel P5 for each system to check operation of the warning circuit.
2. Mach Airspeed Warning Switch
A. The switch assembly is built within the captain's and the first officer's mach airspeed indicators. Conditions of high mach airspeed will trigger an electronic clacker located in the aural warning devices unit, providing an aural warning signal. The clacker will sound any time the indicated airspeed exceeds the maximum operating airspeed or Mach number. The clackers will remain energized until the airplane's airspeed or Mach number is reduced. For detail operation of the mach airspeed indicators. Refer to 34-12-0, Air Data Pressure Instruments.
3. Mach Airspeed Aural Warning Clackers
A. The mach airspeed aural warning clacker is located in the aural warning and call devices box on the control stand. Upon initiation by the mach airspeed indicators, the clackers provide a distinct warning signal which cannot be mistaken for the aural warning associated with, or activated by, other systems. Refer to Chapter 31, Aural Warning and Call Devices.
5C8
Feb 20/89 34-15-01 Page 1
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H34151
Mach/Airspeed Warning System Component Location 505
34-15-01 Figure 1 Feb 15/81
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BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
MACH AIRSPEED WARNING SYSTEM - ADJUSTMENT/TEST
EFFECTIVITY
GJ 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 to 40 inches of mercury absolute, and gage for measuring differential pressure, accurate within 士0.015 inch of mercury. Range should be at least 10 inches of mercury.
(2)
Air pressure and vacuum source, 5 to 30 inches of mercury absolute
(3)
Pressure gage accurate to within士0.03 inch of mercury
(4)
Appropriate gage saver restrictors
(5)
Adequate lengths of hose to couple pressure source with pitot tubes and vacuum source with static ports or drains
(6)
Pitot static probe adapter -P/N PS22300-3-4-4, Allen Aircraft Radio, Inc, 2050 Touhy Avenue, Elk Grove Village, Illinois 60007
B. Prepare to Test Mach Airspeed Warning System
(1) To prevent damage to equipment and instruments, check following precautions before applying pressures to pitot static system.
(a)
Apply or release vacuum or pressure at rate of climb or descent less than 5000 feet per minute for static system and 300 knots per minute for pitot system between test points. (Appropriate gauge saver restrictors should be used.) At each test point, pressure should be reduced slowly to desired level without overshoot.
(b)
Pressure in pitot lines should always be greater than or equal to pressure in static lines. Differential pressure should never exceed 10.00 inches of mercury or fall below zero.
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