DOC AIRBUS | AMM A320FInspection of the VHF Antenna
TASK 23-12-11-200-801-A
Inspection of the VHF Antenna
1. Reason for the Job
To give the permitted tolerance period in relation to the types of damage of the VHF antennas, that are the results of their exposure to the environment conditions.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
B. Consumable Materials
C. Work Zones and Access Panels
D. Referenced Information
3. Job Set-up
Subtask 23-12-11-941-050-A
Subtask 23-12-11-210-050-A
Subtask 23-12-11-860-058-A
[Rev.10 from 2021]
2026.04.02 06:12:00 UTC
Inspection of the VHF Antenna
1. Reason for the Job
To give the permitted tolerance period in relation to the types of damage of the VHF antennas, that are the results of their exposure to the environment conditions.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
| REFERENCE | QTY | DESIGNATION |
|---|---|---|
| No specific | 1 | ACCESS PLATFORM 6M (20 FT) |
| 98L12003001000 | AR | HARNESS,SAFETY |
| REFERENCE | DESIGNATION |
|---|---|
| (Material No.08BAA9) | Non Aqueous Cleaner-General - - |
| (Material No.14SBA1) | Textile-Lint free Cotton - |
| ZONE/ACCESS | ZONE DESCRIPTION |
|---|---|
| 150 | AFT CARGO COMPARTMENT FWD PRESS BULKHEAD TO AFT BULKHEAD OF AFT CARGO COMPARTMENT |
| 220 | FWD CAB UTILITY AREAS |
| 250 | AFT PASSENGER COMPARTMENT |
| REFERENCE | DESIGNATION |
|---|---|
| TASK 23-12-00-710-001-A | Operational Test of the Very High Frequency (VHF) System |
| TASK 23-12-00-710-802-A | Operational Test of the Multiple VHF Data Radio (MVDR) System |
| TASK 23-12-00-710-803-A | Operational Test of the Very High Frequency (VHF) System |
| TASK 23-12-11-000-001-A | Removal of the VHF Antennas |
| TASK 23-12-11-000-002-A | Removal of the VHF Antenna |
| TASK 23-12-11-400-001-A | Installation of the VHF Antennas |
| TASK 23-12-11-400-002-A | Installation of the VHF Antenna |
-3- CRITICAL DAMAGESubtask 23-12-11-941-050-A
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Subtask 23-12-11-860-057-A B. Aircraft Maintenance Configuration
4. ProcedureWARNING:
BEFORE YOU START WORK, YOU MUST PUT ON A SAFETY HARNESS AND ATTACH IT TO THE ACCESS PLATFORM. WITHOUT A SAFETY HARNESS, YOU CAN FALL. THIS CAN KILL YOU OR CAUSE YOU INJURY.
(1) Make sure that the ACCESS PLATFORM 6M (20 FT) is in position at Zone 150, 220 or 250.- FOR VHF1: [4RC1]
Find the VHF Antenna at zone 220.
Make sure that the inspection area is sufficiently clean to do a satisfactory inspection of the area. - FOR VHF2: [4RC2]
Find the VHF Antenna at zone 150.
Make sure that the inspection area is sufficiently clean to do a satisfactory inspection of the area. - FOR VHF3: [4RC3]
Find the VHF Antenna at zone 250.
Make sure that the inspection area is sufficiently clean to do a satisfactory inspection of the area.
- Put on and attach a 98L12003001000 HARNESS,SAFETY before you start work in the work area.
Subtask 23-12-11-210-050-A
A. Types of damage
(1) There are three types of damage:
(a) If there is a dent because of a pebble or debris that hit the antenna (mechanical damage): This damage occurred between inspection n-1 and inspection n. Thus, you can only find this type of damage during inspection n because the damage was not there during inspection n-1.
Usually, this type of damage is as follows:
Land vehicles or large objects can hit the antenna and cause damage to it. This type of damage is different from those that are the results of debris or pebbles. If a land vehicle or a large object hits the antenna, replace the antenna before the next flight.
(b) If there is corrosion (chemical damage): You can find this type of damage in areas where the paint or coating layers are worn and where you can see the bare metal structure of the antenna. In these bare metal areas, the damage is the result of the environment conditions and corrosive agents. The corrosive agents and the chemical reactions change the chemical composition of the metal parts and cause the deterioration of the mechanical properties of the structure.
When you do the visual inspection, you can find brown and black spots on the gray metal surfaces. Corrosion damage is different from pebble or debris damage because it can increase gradually in a period longer than the interval between two inspections. You cannot find this type of damage on a new antenna or an antenna that had no signs of damage of the paint or coating layers during inspection n-1. The visual inspection of an antenna that is not new and that has signs of erosion and corrosion spots, is sufficient to report the damage as critical (refer to the description of "erosion" in the next step).
(3) Erosion:
Erosion is the type of wear in which damage to the antenna paint layers increases gradually.
The erosion can be:
(b) In this type of erosion, you can see the primer of the antenna but not the bare structure.
Subtask 23-12-11-200-050-B (1) There are three types of damage:
- Critical Damage
- Deep Erosion
- Light Erosion
(a) If there is a dent because of a pebble or debris that hit the antenna (mechanical damage): This damage occurred between inspection n-1 and inspection n. Thus, you can only find this type of damage during inspection n because the damage was not there during inspection n-1.
Usually, this type of damage is as follows:
- Areas with signs of deterioration of the painted surfaces
- Areas with dent, deformation or crack.
Land vehicles or large objects can hit the antenna and cause damage to it. This type of damage is different from those that are the results of debris or pebbles. If a land vehicle or a large object hits the antenna, replace the antenna before the next flight.
(b) If there is corrosion (chemical damage): You can find this type of damage in areas where the paint or coating layers are worn and where you can see the bare metal structure of the antenna. In these bare metal areas, the damage is the result of the environment conditions and corrosive agents. The corrosive agents and the chemical reactions change the chemical composition of the metal parts and cause the deterioration of the mechanical properties of the structure.
When you do the visual inspection, you can find brown and black spots on the gray metal surfaces. Corrosion damage is different from pebble or debris damage because it can increase gradually in a period longer than the interval between two inspections. You cannot find this type of damage on a new antenna or an antenna that had no signs of damage of the paint or coating layers during inspection n-1. The visual inspection of an antenna that is not new and that has signs of erosion and corrosion spots, is sufficient to report the damage as critical (refer to the description of "erosion" in the next step).
(3) Erosion:
Erosion is the type of wear in which damage to the antenna paint layers increases gradually.
The erosion can be:
- Mechanical: Air, dust and small particles can have an abrasive effect on the antenna and can cause wear of the antenna paint layers and of the structure. If you do not repair this type of damage, it can have dangerous effects.
- Chemical: Chemical reactions can cause damage to the paint and erosion to the bare metal.
Erosion can be of two types:
(b) In this type of erosion, you can see the primer of the antenna but not the bare structure.
B. Detailed Inspection of the VHF Antenna
Subtask 23-12-11-750-050-A - Do a detailed inspection of the VHF antenna.
C. Applicable Tolerance Periods
The table that follows gives the tolerance time before you replace the antenna:
During the tolerance period, do the inspection of the antenna before each FC to make sure that the damage did not increase.
If the damage is as given in Table 1, make an entry in the logbook.
If the damage increased quickly, refer to Para. 4.A. to know its criticality and refer to Table 1 for the start of the initial tolerance period.
This means that you must continue to use the number of FCs or days since the first damage detection, and you must use the tolerance period applicable to the new type of damage.
Subtask 23-12-11-710-053-A ** ON A/C NOT FOR ALL The table that follows gives the tolerance time before you replace the antenna:
| Type of damage | Tolerance period |
| Critical damage | Replace the antenna in less than one day. |
| Deep erosion | Replace the antenna before 50 Flight Cycles (FC) or 10 days, the one that occurs first. |
| Light erosion | Replace the antenna before 100 Flight Cycles (FC) or 20 days, the one that occurs first. |
If the damage is as given in Table 1, make an entry in the logbook.
If the damage increased quickly, refer to Para. 4.A. to know its criticality and refer to Table 1 for the start of the initial tolerance period.
This means that you must continue to use the number of FCs or days since the first damage detection, and you must use the tolerance period applicable to the new type of damage.
D. Operational Test
(1) The operational test of the VHF antenna system must be satisfactory in the conditions that follow:
(Ref. AMM TASK 23-12-00-710-001)
Subtask 23-12-11-710-053-B ** ON A/C NOT FOR ALL (1) The operational test of the VHF antenna system must be satisfactory in the conditions that follow:
- At the start of the tolerance period, when you find the damage for the first time, before the first dispatch allowance
- During the tolerance period, if the damage increased quickly and if it is more critical (refer to Para. 4.A. for the criticality and to Para. 4.C. for the next dispatch allowance).
(Ref. AMM TASK 23-12-00-710-001)
D. Operational Test
(1) The operational test of the VHF antenna system must be satisfactory in the conditions that follow:
(Ref. AMM TASK 23-12-00-710-803)
Subtask 23-12-11-710-054-A ** ON A/C NOT FOR ALL (1) The operational test of the VHF antenna system must be satisfactory in the conditions that follow:
- At the start of the tolerance period, when you find the damage for the first time, before the first dispatch allowance
- During the tolerance period, if the damage increased quickly and if it is more critical (refer to Para. 4.A. for the criticality and to Para. 4.C. for the next dispatch allowance).
(Ref. AMM TASK 23-12-00-710-803)
E. Operational Test
(1) The operational test of the VHF antenna system must be satisfactory in the conditions that follow:
(Ref. AMM TASK 23-12-00-710-802)
Subtask 23-12-11-960-050-A (1) The operational test of the VHF antenna system must be satisfactory in the conditions that follow:
- At the start of the tolerance period, when you find the damage for the first time, before the first dispatch allowance
- During the tolerance period, if the damage increased quickly and if it is more critical (refer to Para. 4.A. for the criticality and to Para. 4.C. for the next dispatch allowance).
(Ref. AMM TASK 23-12-00-710-802)
F. Replacement of the antenna
At the end of the grace period, replace the antenna.
(Ref. AMM TASK 23-12-11-000-001)
(Ref. AMM TASK 23-12-11-400-001)
(Ref. AMM TASK 23-12-11-000-002)
(Ref. AMM TASK 23-12-11-400-002)
5. Close-upAt the end of the grace period, replace the antenna.
(Ref. AMM TASK 23-12-11-000-001)
(Ref. AMM TASK 23-12-11-400-001)
(Ref. AMM TASK 23-12-11-000-002)
(Ref. AMM TASK 23-12-11-400-002)
Subtask 23-12-11-860-058-A
A. Put the aircraft back to its initial configuration.
(1) Remove the access platform(s).
Subtask 23-12-11-942-053-A (1) Remove the access platform(s).
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