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4. _________________
LRRA System No. 3
EFFECTIVITY
CONFIG 4
LH ALL
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PROCEDURE 1
T34448
EFFECTIVITY
CONFIG 4
LH ALL;
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IB 405
Apr 25/88
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LOW RANGE RADIO ALTIMETER (LRRA) SYSTEM - ADJUSTMENT/TEST
_________________________________________________________
1. Operational Test - LRRA System
______________________________
A. General
(1)
The operational test procedure verifies proper operation of the LRRA system in a minimum of time using the built-in test feature of the equipment.
(2)
To test LRRA system No. 1, use the captain's controls and instruments. To test LRRA system No. 2, use the first officer's controls and instruments.
(3)
On airplanes with a third LRRA (fail ops) system installed, the third system (LRRA-3) does not contain any control cabin controls or height indicator which allow an operational test to be performed. However, the LRRA-3 failure annunciator on the center instrument panel is checked to verify that no failure indication is displayed when the system is operating. A black display at the LRRA-3 annunciator indicates no failure and a red display indicates a malfunction.
B. Referenced Procedures
(1)
21-58-00, Adjustment/Test (Operational Test)
(2)
24-22-00, Maintenance Practices (Apply Power)
C. Prepare for Test
(1)
Provide electrical power (Ref 24-22-00).
(2)
Operate equipment cooling system (Ref 21-58-00).
(3)
Close ALTM LOW R1 and ALTM LOW R2 circuit breakers on overhead circuit breaker panel P7.
(4)
On airplanes with a LRRA-3 system, close circuit breaker ALTM LOW R3 on circuit breaker panel P126.
(5)
On AT, MD, GN airplanes and AF freighters 151-154, turn on LRRA systems 1 and 2 at captain's and first officer's height indicators, respectively.
D. Test LRRA System
NOTE: On IB 406-410 incorporating SB 34-2201,
____ the DH light on height indicators and rising runway altitude function on ADIs are inoperative.
(1)
At captain's height indicator, set DH index to between -15 and -20 feet and check that:
(a)
Captain's DH light(s) off. If not off, cycle ALTM LOW R1 circuit breaker at P7 panel off and then on to extinguish captain's DH light(s).
(b)
Warning flag on captain's height indicator is out of view.
(c)
Altitude pointer on captain's height indicator indicates between -3 and -11 feet.
(d)
On SN airplanes and AF 195-199, audio tone is heard in captain's headset or cockpit speaker.
(2)
At captain's height indicator, press and hold self-test switch and check that:
(a)
Captain's DH light(s) is/are off.
(b)
Warning flag on captain's height indicator comes into view.
EFFECTIVITY
ALL 41 Page 501 Apr 25/9834-33-00
(c) On ALL EXCEPT LH airplanes, altitude pointer on captain's XA height indicator indicates 100 |10 feet. On LH airplanes XA altitude pointer on captain's height indicator indicates XA 40 |5 feet.
(d)
On SN airplanes, audio tone comes on at interphone panel and increases in intensity as DH index on captain's height indicator is slowly adjusted to increasing altitude setting. Captain's DH light(s) come on and audio tone stops when DH altitude setting is within | 5 feet of displayed test altitude.
(e)
On ALL EXCEPT SN airplanes, as DH index on captain's height indicator is slowly adjusted to increasing altitude setting, captain's DH light comes on when DH altitude setting is within | 5 feet of displayed test altitude.
(3)
Release self-test switch and check that:
(a)
Captain's DH light(s) remains on.
(b)
Warning flag on captain's height indicator retracts from view.
(c)
Altitude pointer on captain's height indicator returns to -3 to -11 feet indication.
(4)
Repeat previous steps except use first officer's controls and equipment (LRRA system No. 2) in place of captain's.
(5)
On AF, AT, GN, MD Airplanes, readjust DH index on captain's height indicator until captain's DH light comes on; then, push in on captain's DH control knob and check that DH light goes out. Readjust DH index to between -15 and -20 feet.
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