(2)
Perform operational check system. If the system is still malfunctioning, replace height indicator
(3)
If system still malfunctions, inspect antennas for damage, airplane wiring and all connectors for improper connections or damaged items.
B. The following malfunctions are traceable to the height indicator. If the system operation is normal and one or more of the following malfunctions occur, do not replace the receiver-transmitter first. Instead, replace the height indicator and recheck system operation. If not OK, replace receiver-transmitter.
(1)
Dial lighting
(2)
DH trip lights
(3)
DH control knob or cursor/self-test
(4)
Flag not visible when circuit breaker is pulled.
C. Altitude trips supplied by the radio altimeter system but not used for altitude indication by the radio altitude system are covered in the chapter for the using system. See simplified schematic in 34-48-0, Description and Operation.
D. DH light on ADI's can be tested for failed lamp by pressing light face.
5C8
Oct 20/85 34-48-0 Page 101
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
LOW RANGE RADIO ALTIMETER SYSTEM - ADJUSTMENT/TEST
EFFECTIVITY
GJ ALL EXCEPT B-2509, B-2510
1. Low Range Radio Altimeter System Test
A. Prepare to Test Low Range Radio Altimeter System
(1)
Provide electrical power.
(2)
Check that RADIO ALTM-1 circuit breaker on panel P18 and RADIO ALTM-2 circuit breaker on panel P6 are closed.
(3)
Allow a 5 minute warm-up period.
B. Test Low Range Radio Altimeter System
(1)
At both height indicators check that:
(a)
Altitude pointer indicates between 0 and -10 feet.
(b)
Warning flag is out of view.
(2)
At captain's height indicator, turn the decision height control to the lower mechanical stop, and check that:
(a) DH light is extinguished.
(3)
At captain's height indicator, press the self-test switch and check that:
(a)
DH light is extinguished.
(b)
Altitude pointer on height indicator indicates 400 +40 feet.
(c)
Warning flag on height indicator is in view.
NOTE: Flag is out of view for series II R/T units. Flag is in view for series III R/T units. Series designation is on R/T nameplate.
(4)
While pressing the test switch in, turn the decision height control on the captain's height indicator until the Captains DH light comes on. Check that:
(a) The DH cursor shall be within + 10 feet of the indicated test altitude.
(5)
Release test switch on the captain's height indicator and check that:
(a)
Altitude pointer on height indicator returns to 0 to -10 feet indication.
(b)
Warning flag on height indicator retracts from view. See Note in step (3) above.
(6)
Return the Captain's decision height control to the lower mechanical stop. Check that:
(a) The captain's DH light shall go off.
(7)
Repeat steps 1.B.(2) thru (6) using first officer's height indicator in place of captain's height indicator.
(8)
Open the RADIO ALTM-1 circuit breaker. On captain's height indicator, check that:
(a)
Warning flag comes into view.
(b)
Altitude pointer shall "freeze".
(9)
Close the RADIO ALTM-1 circuit breaker. Warning flag goes out of view and altitude pointer returns to 0 to -10 feet indication.
(10)
Repeat (8) and (9) using RADIO ALTM-2 circuit breaker and first officer's height indicator in place of captain's height indicator.
5C8
Oct 20/85 34-48-0 Page 501
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
LOW RANGE RADIO ALTIMETER SYSTEM - DESCRIPTION AND OPERATION
EFFECTIVITY
WA ALL EXCEPT N235WA, N4502W thru N4571M GJ B2509, B2510
1. General
A. The low range radio altimeter (LRRA) system provides vertical position information for use by the pilots during approach and landing phases of flight operation. The LRRA system provides measurement of absolute altitude (height above terrain) from 2500 feet to touchdown. Flag alarm, A/P failure warning, dc altitude, and vertical terrain clearance (altitude trip) outputs are available for use by other systems.
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