Installation of the Radio Altimeter (RA) Antenna

TASK 34-42-11-400-001-A
Installation of the Radio Altimeter (RA) Antenna

WARNING: BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.

ZONE: 150
FIN: 5SA1
FIN: 5SA2
FIN: 6SA1
FIN: 6SA2

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	SCRAPER - NON METALLIC

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.04JAA3)	Top Coat Polyurethane_- - External Structure
(Material No.04QAB2)	Coating_- Flexible Structure
(Material No.04SAB2)	Varnish Polyurethane-- Marking Structure
(Material No.04TMB2)	Varnish-- Electrical Bonding Structure
(Material No.06AAB1)	Polysulfide Sealant-General Purpose Fillet -
(Material No.06ABA1)	Polysulfide Sealant-Fuel Tank Brushable -
(Material No.06ABF1)	Polysulfide Sealant-Fuel Tank Quick Curing -
(Material No.06AFB1)	Polysulfide Sealant-Windshield Fillet -
(Material No.08BBD1)	Non Aqueous Cleaner-- Isopropyl Alcohol -
(Material No.14SBA1)	Textile-Lint free Cotton -

C. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
150	AFT CARGO COMPARTMENT FWD PRESS BULKHEAD TO AFT BULKHEAD OF AFT CARGO COMPARTMENT

D. Expendable Parts

FIG.ITEM	DESIGNATION	IPC-CSN
7	GASKET	AIPC 34-42-04-01-060
10	SHEATH	AIPC 34-42-04-01-070
9	TUBING	AIPC 34-42-04-01-080
6	O-RING	AIPC 34-42-11-01-010
7	GASKET	AIPC 34-42-84-01-070
10	SHEATH	AIPC 34-42-84-01-080
9	TUBING	AIPC 34-42-84-01-090

E. Referenced Information

REFERENCE	DESIGNATION
TASK 20-28-00-912-802-A	Electrical Bonding - General Maintenance Procedure
TASK 20-28-00-912-803-A	Bonding Surface Preparation
TASK 24-42-00-861-001-A	Energize the Ground Service Network from the External Power
TASK 24-42-00-862-001-A	De-energize the Ground Service Network Supplied from the External Power
TASK 34-42-00-740-002-A	BITE Test of the Radio Altimeter
Radio Altimeter Antennas with Gasket for Water Ingress Protection
Radio Altimeter Antenna - Front Face

3. Job Set-up
Subtask 34-42-11-860-050-A

A. Aircraft Maintenance Configuration
(1) Make sure that the ground service network is energized
(Ref. AMM TASK 24-42-00-861-001).
(2) Make sure that the parts retained from the removed component are clean and in the correct condition.

Subtask 34-42-11-865-051-A

B. Make sure that this(these) circuit breaker(s) is(are) open, safetied and tagged:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
FOR FIN: 5SA1 (ANTENNARA RCPTN, 1)
121VU	COM NAV/RAD ALTM/1	1SA1	K11
FOR FIN: 6SA1 (ANTENNARA XMSN, 1)
121VU	COM NAV/RAD ALTM/1	1SA1	K11
FOR FIN: 5SA2 (ANTENNARA RCPTN, 2)
121VU	COM NAV/RAD ALTM/2	1SA2	K12
FOR FIN: 6SA2 (ANTENNARA XMSN, 2)
121VU	COM NAV/RAD ALTM/2	1SA2	K12

4. Procedure
Subtask 34-42-11-140-052-B

A. Preparation for the Installation of the Radio Altimeter (RA) Antenna
(1) Use the SCRAPER - NON METALLIC to remove the remaining sealant form the fuselage structure (1).
(2) Clean the component interface and/or the adjacent area with the Non Aqueous Cleaner-- Isopropyl Alcohol - (Material No.08BBD1) and a Textile-Lint free Cotton - (Material No.14SBA1) .
(3) Do an inspection of the component interfaces and the adjacent area.
(4) Make sure that the O-ring (6) is in the correct condition.
(a) If the O-ring (6) is not in the correct condition, install a new AIPC 34-42-11-01-010 O-RING (6) on the RA antenna (4).
(5) Install the O-ring (6) on the RA antenna (4).
(6) Install a new AIPC 34-42-04-01-060 GASKET (7) on the RA antenna (4):

NOTE: The gel gasket (7) is a self-adhesive gasket. The two faces of the gel gasket are self-adhesive. It protects the RA antenna (4) from water.

(a) Remove the protection film from the RA antenna (4) side of the gel gasket (7).
(b) Align the fastener holes of the gel gasket (7) with the fastener holes of the RA antenna (4).
(c) Bond the gel gasket (7) to the RA antenna (4).
(7) If the gel gasket (7) is not available:
(a) Install a new AIPC 34-42-84-01-070 GASKET (7) on the RA antenna (4).
(b) If the Teflon gasket (7) that you removed is damaged, install the new AIPC 34-42-84-01-070 GASKET (7) on the RA antenna (4).
(c) If the Teflon gasket (7) that you removed is not damaged, install it on the RA antenna (4).

Subtask 34-42-11-420-056-D

B. Installation of the Radio Altimeter (RA) Antenna
(1) Prepare the surface of the bonding point(s)
(Ref. AMM TASK 20-28-00-912-803).
(2) Shrink the AIPC 34-42-04-01-070 SHEATH (10) or the AIPC 34-42-84-01-080 SHEATH (10) below the thread (12) of the antenna connector (3).
(3) Push the new AIPC 34-42-04-01-080 TUBING (9) or the AIPC 34-42-84-01-090 TUBING (9) on the coaxial cable.
(4) Remove the CAP-BLANKING from each electrical connector and receptacle.
(5) Make sure that all the electrical connections are clean and in the correct condition.
(6) Connect the coaxial connector (2) to the thread (12) of the antenna connector (3) with the locknut (11).
(7) Make sure that the "FWD" sign or the datum mark on the antenna is in the flight direction.

CAUTION: DO NOT TIGHTEN THE COAXIAL CONNECTORS TOO MUCH. IF YOU TIGHTEN THE COAXIAL CONNECTORS TOO MUCH, YOU CAN CAUSE DAMAGE TO THEM.

(8) Tighten the coaxial connector (2).
(9) Apply a stripe of the Varnish Polyurethane-- Marking Structure (Material No.04SAB2) on the connectors (2) and (3).
(10) Shrink the tubing (9) on the connectors (2) and (3).
(11) Apply sealant:
(a) Apply some of the Polysulfide Sealant-Fuel Tank Brushable - (Material No.06ABA1) or the Polysulfide Sealant-Windshield Fillet - (Material No.06AFB1) on:

The ends of the shrink sleeve (8) and the tubing (9)
The antenna body (inner part of the O-ring).

NOTE: The gel gasket (7) bonded on the RA antenna (4) is self-adhesive on the aircraft side.

(b) Apply the Polysulfide Sealant-General Purpose Fillet - (Material No.06AAB1) or the Polysulfide Sealant-Fuel Tank Quick Curing - (Material No.06ABF1) on the adjacent area of the RA antenna (4) flange on an area of approximately 3 MM (0.1181 IN.) wide.
(12) Install the RA antenna (4):
(a) If you install the gel gasket (7):
1 Remove the protection film from the aircraft side of the gel gasket (7).
2 Install the screws (5) through the RA antenna (4) and the gel gasket (7).
3 Make sure that there is no gel gasket on the threads of the screws (5).
4 Align the fastener holes of the RA antenna (4) with the fastener holes of the fuselage structure (1).
5 Bond the RA antenna (4) to the fuselage structure (1).
(b) If you install the Teflon gasket (7):
1 Put the RA antenna (4) in position on the fuselage structure (1).
2 Align the fastener holes of the RA antenna (4) with the fastener holes of the fuselage structure (1).
3 Install the antenna mounting screws (5) on the RA antenna (4).
(13) Tighten the screws (5) in a diagonally opposite sequence.
(14) Wait a minimum of 15 minutes to let the gel gasket (7) cure.
(15) Tighten the screws (5) again.
(16) Do the electrical resistance measurement and the final protection of the bonding point(s)
(Ref. AMM TASK 20-28-00-912-802).
(17) Apply new sealant on the antenna (4) and the screws (5):
(a) Apply a bead of the Polysulfide Sealant-General Purpose Fillet - (Material No.06AAB1) or the Polysulfide Sealant-Fuel Tank Quick Curing - (Material No.06ABF1) around the RA antenna (4).
(b) Apply the Polysulfide Sealant-General Purpose Fillet - (Material No.06AAB1) or the Polysulfide Sealant-Fuel Tank Quick Curing - (Material No.06ABF1) on the heads of the screws (5).
(c) Make the contour of the sealant smooth on the screws (5) and around the RA antenna (4).
(18) Let the sealant cure.
(19) Apply paint on the sealant:

Radio Altimeter Antenna - Front Face

(a) Make sure that you do not apply paint in the active area. Apply paint only out of the circular area of diameter D + 6 MM (0.24 IN.).
(b) Apply the Coating_- Flexible Structure (Material No.04QAB2) or the Top Coat Polyurethane_- - External Structure (Material No.04JAA3) on the sealant around the bottom of the RA antenna (4).

NOTE: It is not mandatory to apply paint on the sealant that is around the bottom of the antenna (4) and on the heads of the screws (5).

Subtask 34-42-11-914-051-A

CAUTION: AFTER TEN DAYS OF FLIGHT WITH INTERPOSITION SEALANT OR A GEL/ SILICON GASKET, DO THESE STEPS:

CLEAN THE AREA AROUND THE ANTENNA, AND
APPLY A SEALANT BEAD AROUND THE ANTENNA AND/OR SEALANT ON THE HEADS OF THE SCREWS.

IF YOU DO NOT DO THIS, WATER CAN GO INTO THE STRUCTURE AND CORROSION CAN OCCUR.

CAUTION: AFTER THREE DAYS OF FLIGHT WITHOUT SEALANT, DO THE FULL INSTALLATION OF THE ANTENNA:

REMOVE THE ANTENNA
CLEAN THE FUSELAGE AND ANTENNA SURFACES AND REMOVE ALL SIGNS OF HUMIDITY.

IF YOU DO NOT DO THIS, WATER CAN GO INTO THE STRUCTURE AND CORROSION CAN OCCUR.

C. Aircraft Antenna Sealant-Exemption

Obey the indications given in the table that follows if it is not possible to:

Apply the sealant.
Let the sealant cure during the applicable curing time.

This table gives the time limits that are applicable for the sealant installation on the radio altimeter antenna.
These limits are adapted to:
The antenna installation configuration
The antenna location
The sensitive condition of the antenna to water infiltration
The available condition of the sealant.

Configuration of the antenna installation	If the airline has sealant but cannot wait until the sealant is cured	If the airline has no sealant available
No sealant (Teflon gasket) between the antenna and the fuselage: 3 mm (0.12 in.) wide sealing below the antenna flange Sealing bead around the antenna Sealant on the heads of the screws O-ring at the antenna connector level.	The installation of a sealing bead around the antenna is mandatory (no exemption possible because of the risk of water infiltration between the aircraft and the antenna). It is permitted to fly for a maximum of 10 days without the sealant on the heads of the screws.	No exemption possible because of the risk of water infiltration between the aircraft and the antenna. It is permitted to fly for a maximum of 3 days without the sealant (Teflon gasket, sealing bead and sealant on the heads of the screws), if the O-ring is installed.
No sealant (Teflon gasket) between the antenna and the fuselage: Sealing bead around the antenna Sealant on the heads of the screws O-ring at the antenna connector level.	The installation of a sealing bead around the antenna is mandatory (no exemption possible because of the risk of water infiltration between the aircraft and the antenna). It is permitted to fly for a maximum of 10 days without the sealant on the heads of the screws.	No exemption possible because of the risk of water infiltration between the aircraft and the antenna. It is permitted to fly for a maximum of 3 days without the sealant (Teflon gasket, sealing bead and sealant on the heads of the screws), if the O-ring is installed.
Polyurethane gel gasket between the antenna and the fuselage: Sealing bead around the antenna Sealant on the heads of the screws O-ring at the antenna connector level.	It is permitted to fly for a maximum of 10 days without the sealing bead around the antenna, if the interposition gasket and the O-ring are installed. It is permitted to fly for a maximum of 10 days without the sealant on the heads of the screws, if the interposition gasket and the O-ring are installed.	It is permitted to fly for a maximum of 3 days without the sealant (interposition gasket, sealing bead and sealant on the heads of the screws), if the O-ring is installed.

NOTE: When there is no sealing bead, there is a risk of aerodynamic noise.

Subtask 34-42-11-865-052-A

D. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
FOR FIN: 5SA1 (ANTENNARA RCPTN, 1)
121VU	COM NAV/RAD ALTM/1	1SA1	K11
FOR FIN: 6SA1 (ANTENNARA XMSN, 1)
121VU	COM NAV/RAD ALTM/1	1SA1	K11
FOR FIN: 5SA2 (ANTENNARA RCPTN, 2)
121VU	COM NAV/RAD ALTM/2	1SA2	K12
FOR FIN: 6SA2 (ANTENNARA XMSN, 2)
121VU	COM NAV/RAD ALTM/2	1SA2	K12

Subtask 34-42-11-740-050-A

E. Test
(1) Do the BITE test of the radio altimeter (Ref. AMM TASK 34-42-00-740-002).

5. Close-up
Subtask 34-42-11-862-050-A

A. Aircraft Maintenance Configuration
(1) De-energize the ground service network
(Ref. AMM TASK 24-42-00-862-001).

[Rev.10 from 2021] 2026.04.01 04:04:39 UTC