(22)
All XA except AF 121, 122, 157, 161, 183, 184; No alerting indication occurs when the airplane altitude deviates less than 350 feet from the selected altitude. As the airplane deviates more than 350 feet from the selected altitude, the microprocessor and peripheral interface adapter activate the annunciators through the flashing circuit.
(23)
AF 121, 122, 157, 161, 183, 184; No alerting indication occurs when the airplane altitude is less than 300 feet from the selected altitude. As the airplane deviates more than 300 feet from the selected altitude, the microprocessor and peripheral interface adapter activate the annunciators through flashing circuit.
(24)
All XA except AF 121, 122, 157, 161, 183, 184; as the airplane deviates more than 950 feet from selected altitude, the annunciators are turned off.
(25)
XA 121, 122, 157, 161, 183, 184; as the airplane deviates more than 900 feet from selected altitude, the annunciators are turned off.
(26)
The altitude alert computer is then ready for re-entry.
(27)
The computer inhibits the alerting signals for 2 seconds when a new altitude is selected.
(28)
The computer continuously monitors the validity signal from CADC No. 2, the data signals, and electrical power. Loss of any of these signals will activate the aural warning module and turn on all annunciators steadily.
(29)
The gear down sensor inhibits the deviation alert signals whenever the landing gear is extended.
(30)
On airplanes with Smiths Industries digital altitude alert computer 70-200-07 or 70-200-009, a voltage comparator circuit eliminates nuisance warnings due to power transients.
(31)
A system self-test may be performed by pressing the TEST switch and slowly adjusting the selected altitude on the ALT SEL indicator from 1200 feet above the airplane altitude to the airplane altitude and back to 1200 feet above the airplane altitude. The corresponding aural and visual indications will occur when each level is crossed as described previously for normal system operation.
B. Controls
EFFECTIVITY
ALL 01 Page 11 Sep 25/9434-16-00
(1)
The ALTIT ALERT COMP and ALTIT ALERT MON circuit breakers on circuit breaker panel P7 control the 28-volt dc and the 26-volt ac power to the computer. The altitude alert system operates continuously whenever the flight instrument bus No. 2 is energized.
(2)
System controls include the altitude alert system test switch and the landing gear down interlock circuit.
EFFECTIVITY
ALL 03 Page 12 Sep 25/9434-16-00
ALTITUDE ALERT SYSTEM - TROUBLE SHOOTING
________________________________________
1. General
_______
A. The following trouble shooting procedures are based on performance of the system operational test and are presented in tree-type format. The test steps (heavy-line boxes) are connected by shaded arrows to show the OK condition path. When all steps in the OK condition path check out, the system is operable.
B. When a test step does not check out, follow the NOT OK line to the box containing the trouble symptom. Turn to the procedure indicated and continue to follow a single line by analyzing the results of each test step until the required corrective action is determined. Perform the specified corrective action; then repeat the step at which the failure was encountered.
C. All trouble shooting procedures are based on the assumption that wiring is OK and that electrical power is available. If the corrective action in the procedure does not correct the problem, check wiring using the wiring diagram.
2. Prepare for Trouble Shooting
____________________________
A. Verify that ALTIT ALERT COMP and MON; CADC NO. 2 PWR and SYNC EXCIT; ALTIM IND 2 circuit breakers on panel P7 are closed.
B. Verify that AURAL WARN; landing gear PRIM DIS & CONT and ALT DIS & CONT; pilots' IND LTS circuit breakers on panel P12 are closed.
C. Provide electrical power (Ref 24-22-00, Maintenance Practices).
D. Set barometric pressure on first officer's altitude indicator to 29.92 in. Hg.
E. Set ALT SEL control on autopilot-flight director mode select panel to airplane altitude.
F. Set master dim and test control to TEST. Check that all altitude alert annunciators come on. Replace defective light bulbs as necessary (Ref 33-11-00, Trouble Shooting).
EFFECTIVITY
ALL 03 Page 101 Oct 10/7334-16-00
Set ALT SEL control to 1000 feet above or below airplane altitude as read on F/O's altitude indicator. Press and hold altitude alerting system TEST switch. Slowly adjust ALT SEL control to 800 feet from airplane altitude. Check that C chord tone from aural warning module sounds 2 (| 1/2) seconds and annunciators come on as selected altitude reaches 900 (| 100) feet from airplane altitude. iF - 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：747飞机维护手册AMM CHAPTER 34 - NAVIGATION 第34章导航1(114)
