(3)
Mach number indication is presented on a two drum digital readout through the range .40 to .99 mach. Below .40 mach the readout is covered by a mach flag. The mach readout mechanism is driven by corrected electronic mach number signals processed by the air data computer. Upon power failure, or loss of 28 volts dc from the air data computer, a striped red and white OFF flag will appear to cover the digital mach readout.
(4)
The colored pointer on the indicator shows maximum operating speed of the airplane as a function of corrected altitude mach and airspeed from the air data computer. The "INOP" flag indicates the absence of an operational performance data computer system. Pulling the bug set knob out will retract flag. White peripheral pointers may be set manually to any desired airspeeds. When operating in the manual mode, an "M" flag will appear in view at the top of the indicator.
(5)
The airspeed/mach indicator operates from a 26 volt ac power supply controlled by a circuit breaker on electronic panel P18-2.
517
Feb 15/79 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 34-12-0 Page 2A/2B
K85824
5C8 Airspeed/Mach Indicators
Jan 20/83 Figure 2 34-12-0
Page 3
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
3. Instantaneous Vertical Speed/Rate of Climb Indicators
A. Instantaneous vertical speed/rate of climb indicators are provided for both the captain and first officer and are operated by static pressure applied to both the inside of the instrument case through an orifice and to the interior of a flexible diaphragm within the case. As the airplane changes altitude the pressure inside the diaphragm changes more rapidly than that inside the instrument case. The resulting differential causes the diaphragm to expand or contract, and the amount of change is proportional to the rate of change of altitude and is indicated by a radial pointer in thousands of feet per minute. An accelerometer is incorporated in the instrument also, and provides indication of instantaneous vertical speed (Fig. 3).
B. A small screw, installed on the lower left corner of the instrument, is used to adjust the pointer to zero.
NOTE: The adjustment screw range for zeroing the vertical speed indicators is from 400 ft./min. DOWN to 400 ft./min. UP. The instrument cannot be harmed by turning the zero adjustment screw too far in either direction. Recalibration of the IVSI is not necessary after the zero adjustment is accomplished, but if it cannot be zeroed, the instrument must be recalibrated.
H30349
Instantaneous Vertical Speed/Rate of Climb Indicators 501
34-12-0 Figure 3 May 15/81
Page 4
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
4. Altimeters
A. Altimeters are provided for both the captain and first officer. The captain's altimeter is an electric drum-pointer type that receives altitude information from the central air data computer. The altimeter in turn provides altitude information to the altitude alert system. The altitude is displayed in 1000-, 100-, and 20-foot increments on drum counters and in 100- and 20-foot increments by a pointer which reads against a fixed scale. The range of the altimeter is from -1000 to 50,000 feet with altitudes below sea level displayed by the rotating pointer and a NEG flag covering the counter drums. A red warning flag will cover the counter drums in the event of a failure. The failure monitor will show the flag in the event of the following: loss of electrical power to the indicator, loss of flag power from the CADC, excessive servo null voltage, loss of input synchro signal and internal indicator malfunction. A barometric pressure setting knob is provided to adjust the pressure setting which is displayed in both millibars and inches of mercury.
B. The first officer's altimeter is a pneumatic drum-pointer type. The range of the altimeter is from -1000 to 50,000 feet and is displayed in 1000- and 100-foot increments on drum counters and in 100- and 20-foot increments by a pointer which reads against a fixed scale. A barometric pressure setting knob is provided to adjust the pressure setting which is displayed in both millibars and inches of mercury. An instrument vibrator is contained in the altimeter to remove mechanical linkage friction errors.
K84352
5C8 Altimeters
Oct 20/85 Figure 4 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 34-12-0 Page 5
5. Digital Air Data Computer
A. General
(l)
The digital air data computer (DADC) is a solid-state device that uses pitot static pressures and air temperature inputs to compute air data information required by airplane displays and systems. In addition to the above inputs, 115-volt ac and 26-volt ac are provided to a multipin connectors at the rear of the computer.
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