(3)
LRRA receive antenna, M1739 (No. 1) or M1740 (No. 2).
(4)
Wiring.
C. Circuit Breakers
(1) These are the primary circuit breakers related to the fault:
CAPT Electrical System Panel, P18-1
Row Col Number Name
B 4 C01384 RADIO NAVIGATION RADIO ALTM 1
F/O Electrical System Panel, P6-1
Row Col Number Name
A 16 C01385 RADIO NAVIGATION RADIO ALTM 2
D. Related Data
(1)
(SSM 34-33-11).
(2)
(SSM 34-33-21).
(3)
(WDM 34-33-11).
(4)
(WDM 34-33-21).
E. Initial Evaluation
(1) Do
this
task:
Low
Range
Radio
Altimeter
(LRRA)
BITE
Procedure,
34-33
TASK
801.
EFFECTIVITY
34-33 TASKS 804-805
SIL ALL
Page 211 D633A103-SIL Feb 15/2010
(a)
If the radio altimeter display and the RA flag do not show on the captain’s or F/O’s displays, then do the Fault Isolation Procedure below.
(b)
If the radio altimeter display shows on the captain’s or F/O’s displays, then there was an intermittent fault.
F. Fault Isolation Procedure
(1) Use a time domain reflectometer (TDR) test set time domain reflectometer, COM-5187to do an electrical check of the coaxial cable and antenna:
(a)
Remove the LRRA receiver/transmitter. To remove it, do this task: Low Range Radio Altimeter (LRRA) Receiver/Transmitter (R/T) Removal, AMM TASK 34-33-21-000-801.
(b)
Connect the TDR test set time domain reflectometer, COM-5187at pins 71 and C71 of the applicable connector at the LRRA receiver/transmitter (WDM 34-33-11, WDM 34-33-21).
LRRA
TDR CONNECTOR
LRRA-1 (M1735) TEST SET D3667B
XMTR ANTENNA
TDR --------------------pin71 TDR --------------------pinC71
LRRA-1 (M1735) TEST SET D3667A
RCVR ANTENNA
TDR --------------------pin71 TDR --------------------pinC71
LRRA-2 (M1736) TEST SET D3669
XMTR ANTENNA
TDR --------------------pin71 TDR --------------------pinC71
LRRA-2 (M1736) TEST SET D3669A
RCVR ANTENNA
TDR --------------------pin71 TDR --------------------pinC71
(c)
Do an electrical check of the coaxial cable and the antenna.
NOTE: The TDR test set has instructions which tell how to do the check of the cable and antenna.
(d)
Disconnect the TDR test settime domain reflectometer, COM-5187.
(e)
Re-install the LRRA receiver/transceiver. To install it, do this task: Low Range Radio Altimeter (LRRA) Receiver/Transmitter (R/T) Installation, AMM TASK 34-33-21-400-801.
(f)
If you find a problem with the coaxial cable, then do these steps: 1) Replace the coaxial cable (WDM 34-31-11). 2) Do
this
task:
Low
Range
Radio
Altimeter
(LRRA)
BITE
Procedure,
34-33
TASK
801.
3) If the radio altimeter display shows on the captain’s or F/O’s displays, then you
corrected the fault.
(g) If you find a problem with the antenna, then do these steps:
1) Replace the LRRA antenna.
These are the tasks:
EFFECTIVITY SIL ALL 34-33 TASK 805
D633A103-SIL BOEING PROPRIETARY -Copyright # Unpublished Work -See title page for details Page 212 Feb 15/2010
Low Range Radio Altimeter (LRRA) Antenna Installation, AMM TASK 34-33-11-400-801.
2) Do
this
task:
Low
Range
Radio
Altimeter
(LRRA)
BITE
Procedure,
34-33
TASK
801.
3) If the radio altimeter display shows on the captain’s or F/O’s displays, then you corrected the fault. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：737-600/700/800/900 FAULT ISOLATION MANUAL 故障隔离手册 导航(124)
