Radio Altitude Set to No Computed Data

TASK 34-42-00-810-845-A
Radio Altitude Set to No Computed Data

1. Possible Causes

ANTENNA-RA RCPTN, 1 [5SA1]
ANTENNA-RA XMSN, 1 [6SA1]
coaxial cables between the RA transceiver 1 (2SA1) pins AA/C and AB/C and the radio altimeter antennas
ANTENNA-RA RCPTN, 2 [5SA2]
ANTENNA-RA XMSN, 2 [6SA2]
XCVR-RA, 1 [2SA1]
XCVR-RA, 2 [2SA2]

2. Job Set-up Information
A. Consumable Materials

REFERENCE	DESIGNATION
(Material No.08BBD1)	Non Aqueous Cleaner-- Isopropyl Alcohol -
(Material No.14SBA1)	Textile-Lint free Cotton -

B. Referenced Information

REFERENCE	DESIGNATION
ESPM 2052230
ESPM 2053230
ASM 344201
AWM 344201
ASM 344202
AMM 34-42-11-000-001	Removal of the Radio Altimeter Antenna
AMM 34-42-11-400-001	Installation of the Radio Altimeter Antenna
AMM 34-42-11-615-001	Cleaning of the External Surface of the Radio Altimeter Antennas
AMM 34-42-11-920-001	Radio Altimeter Antennas and Coaxial Cables Replacement

3. Fault Confirmation
Subtask 34-42-00-700-055-A

A. Not applicable, you cannot confirm this fault on the ground.

4. Fault Isolation
Subtask 34-42-00-810-100-A

A. If the fault symptom is identified by the crew observation Radio Altimeter - category downgrades with no BITE message:

clean the external surface of the radio altimeter antennas with Non Aqueous Cleaner-- Isopropyl Alcohol - (Material No.08BBD1) and a Textile-Lint free Cotton - (Material No.14SBA1) AMM 34-42-11-615-001.

Subtask 34-42-00-810-102-A

B. After the subsequent flight, if the above entry is shown in the log-book:
For the CAPT side:

remove the ANTENNA-RA RCPTN, 1 [5SA1] and the ANTENNA-RA XMSN, 1 [6SA1] AMM 34-42-11-000-001.

(1) Make sure that the coaxial cables between the RA transceiver 1 (2SA1) pins AA/C and AB/C and the radio altimeter antennas are in correct condition (no corrosion) ASM 344201.
(a) If the antenna coaxial cables are not in correct condition:

repair or replace if necessary the defective coaxial cables ESPM 2053230.
install a new ANTENNA-RA RCPTN, 1 [5SA1] and a new ANTENNA-RA XMSN, 1 [6SA1] AMM 34-42-11-400-001.

(b) If the antenna coaxial cables are in correct condition:

install a new ANTENNA-RA RCPTN, 1 [5SA1] and a new ANTENNA-RA XMSN, 1 [6SA1] AMM 34-42-11-400-001.

Subtask 34-42-00-810-105-A

C. After the subsequent flight, if the above entry is shown in the log-book:
For the F/O side:

remove the ANTENNA-RA RCPTN, 2 [5SA2] and the ANTENNA-RA XMSN, 2 [6SA2] AMM 34-42-11-000-001.

(1) Make sure that the coaxial cables between the RA transceiver 1 (2SA1) pins AA/C and AB/C and the radio altimeter antennas are in correct condition (no corrosion) ASM 344202.
(a) If the antenna coaxial cables are not in correct condition:

repair or replace if necessary the defective coaxial cables ESPM 2053230.
install a new ANTENNA-RA RCPTN, 2 [5SA2] and ANTENNA-RA XMSN, 2 [6SA2] AMM 34-42-11-400-001.

(b) If the antenna coaxial cables are in correct condition:

install a new ANTENNA-RA RCPTN, 2 [5SA2] and ANTENNA-RA XMSN, 2 [6SA2] AMM 34-42-11-400-001.

Subtask 34-42-00-810-116-A

D. If the fault continues:
(1) Do the test of the Radio Altimeter coaxial cables between the RA transceiver 1 XCVR-RA, 1 [2SA1] and the radio altimeter antennas ANTENNA-RA RCPTN, 1 [5SA1] and ANTENNA-RA XMSN, 1 [6SA1] as per ESPM 2052230 AWM 344201.
(a) If the test of coaxial cables is not satisfactory:

replace the coaxial cables 4602VB AMM 34-42-11-920-001 ESPM 2053230.

(2) Do the test of the Radio Altimeter coaxial cables between the RA transceiver 2 XCVR-RA, 2 [2SA2] and the radio altimeter antennas ANTENNA-RA RCPTN, 2 [5SA2] and ANTENNA-RA XMSN, 2 [6SA2] as per ESPM 2052230 AWM 344201.
(a) If the test of coaxial cables is not satisfactory:

replace the coaxial cables 4604VB AMM 34-42-11-920-001 ESPM 2053230.

[Rev.8 from Aug 2018] 2026.04.04 04:38:56 UTC