DOC AIRBUS | AMM A320FLEAK DETECTION - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The function of the continuous monitoring system is to detect ambient overheat issue by means of the detection loops. It is to prevent against possible leaks or bursts of the structure and components near the hot air ducts in the fuselage, pylons and wings.
** ON A/C NOT FOR ALL The function of the continuous monitoring system is to detect ambient overheat issue by means of the detection loops. It is to prevent against possible leaks or bursts of the structure and components near the hot air ducts in the fuselage, pylons and wings.
Leak Detection Loops - General SchematicA. Wing Section
Components for loop A
Components for loop A
| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 21HF | CABLE-CONNECTING, L WING LOOP A | 521 | 36-22-16 | ||
| 22HF | SNSG ELEM-OVHT, L WING LOOP A | 521 | 36-22-16 | ||
| 23HF | SNSG ELEM-OVHT, L WING LOOP A | 522 | 36-22-16 | ||
| 24HF | CABLE-CONNECTING, L WING LOOP A | 522 | 36-22-16 | ||
| 25HF | CABLE-CONNECTING, L WING LOOP A | 522 | 36-22-16 | ||
| 26HF | SNSG ELEM-OVHT, L WING LOOP A | 522 | 36-22-16 | ||
| 27HF | SNSG ELEM-OVHT, L WING LOOP A | 522 | 36-22-16 | ||
| 28HF | SNSG ELEM-OVHT, L WING LOOP A | 521 | 36-22-16 | ||
| 29HF | SNSG ELEM-OVHT, L WING LOOP A | 521 | 36-22-16 | ||
| 49HF | SNSG ELEM-OVHT, L WING LOOP B | 521 | 36-22-16 | ||
| 50HF | SNSG ELEM-OVHT, L WING LOOP B | 522 | 36-22-16 | ||
| 51HF | CABLE-CONNECTING, L WING LOOP B | 522 | 36-22-16 | ||
| 52HF | CABLE-CONNECTING, L WING LOOP B | 522 | 36-22-16 | ||
| 53HF | SNSG ELEM-OVHT, L WING LOOP B | 522 | 36-22-16 | ||
| 54HF | SNSG ELEM-OVHT, L WING LOOP B | 522 | 36-22-16 | ||
| 55HF | SNSG ELEM-OVHT, L WING LOOP B | 521 | 36-22-16 | ||
| 56HF | SNSG ELEM-OVHT, L WING LOOP B | 521 | 36-22-16 | ||
| 77HF | CABLE-CONNECTING, L WING LOOP B | 521 | 36-22-16 | ||
| 37HF | CABLE-CONNECTING, R WING LOOP A | 621 | 36-22-16 | ||
| 38HF | SNSG ELEM-OVHT, R WING LOOP A | 621 | 36-22-16 | ||
| 39HF | SNSG ELEM-OVHT, R WING LOOP A | 622 | 36-22-16 | ||
| 40HF | CABLE-CONNECTING, R WING LOOP A | 622 | 36-22-16 | ||
| 41HF | CABLE-CONNECTING, R WING LOOP A | 622 | 36-22-16 | ||
| 42HF | SNSG ELEM-OVHT, R WING LOOP A | 622 | 36-22-16 | ||
| 43HF | SNSG ELEM-OVHT, R WING LOOP A | 622 | 36-22-16 | ||
| 44HF | SNSG ELEM-OVHT, R WING LOOP A | 621 | 36-22-16 | ||
| 45HF | SNSG ELEM-OVHT, R WING LOOP A | 621 | 36-22-16 | ||
| 64HF | CABLE-CONNECTING, R WING LOOP B | 621 | 36-22-16 | ||
| 65HF | SNSG ELEM-OVHT, R WING LOOP B | 621 | 36-22-16 | ||
| 66HF | SNSG ELEM-OVHT, R WING LOOP B | 622 | 36-22-16 | ||
| 67HF | CABLE-CONNECTING, R WING LOOP B | 622 | 36-22-16 | ||
| 68HF | CABLE-CONNECTING, R WING LOOP B | 622 | 36-22-16 | ||
| 69HF | SNSG ELEM-OVHT, R WING LOOP B | 622 | 36-22-16 | ||
| 70HF | SNSG ELEM-OVHT, R WING LOOP B | 622 | 36-22-16 | ||
| 71HF | SNSG ELEM-OVHT, R WING LOOP B | 621 | 36-22-16 | ||
| 72HF | SNSG ELEM-OVHT, R WING LOOP B | 621 | 36-22-16 | ||
| 80HF | SNSG ELEM-OVHT, R WING LOOP A | 621 | 36-22-16 | ||
| 81HF | SNSG ELEM-OVHT, L WING LOOP A | 521 | 36-22-16 | ||
| 82HF | SNSG ELEM-OVHT, R WING LOOP B | 621 | 36-22-16 | ||
| 83HF | SNSG ELEM-OVHT, L WING LOOP B | 521 | 36-22-16 | ||
B. MID Fuselage Section
| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 30HF | CABLE ASSY | 150 | 36-22-18 | ||
| 31HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 32HF | OVERHEAT SENSING ELEM | 140 | 36-22-18 | ||
| 33HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 34HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 35HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 36HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 47HF | ELEMENT-OVERHEAT SENSING | 140 | 36-22-18 | ||
| 48HF | CABLE ASSY | 190 | 36-22-00 | ||
| 57HF | CABLE ASSY | 150 | 36-22-18 | ||
| 58HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 59HF | OVERHEAT SENSING ELEM | 140 | 36-22-18 | ||
| 60HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 61HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 62HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 63HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 73HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 74HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 75HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 76HF | CABLE ASSY | 190 | 36-22-00 | ||
| 78HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 79HF | OVHT SENS ELEMENT | 140 | 36-22-18 | ||
| 90HF | INTERCONNECTING CABLE | 140 | 36-22-16 | ||
| 91HF | INTERCONNECTING CABLE | 140 | 36-22-16 | ||
| 92HF | INTERCONNECTING CABLE | 140 | 36-22-16 | ||
| 93HF | INTERCONNECTING CABLE | 140 | 36-22-16 | ||
C. MID and AFT Fuselage Section
| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 11HF | SENSING ELEMENT-OVERHEAT,WING | 151 | 36-22-17 | ||
| 12HF | OVHT SENS ELEMENT | 151 | 36-22-17 | ||
| 13HF | OVHT SENS ELEMENT | 151 | 36-22-17 | ||
| 14HF | OVHT SENS ELEMENT | 151 | 36-22-17 | ||
| 15HF | OVHT SENS ELEMENT | 161 | 36-22-17 | ||
| 16HF | OVHT SENS ELEMENT | 171 | 36-22-17 | ||
| 17HF | OVHT SENS ELEMENT | 171 | 36-22-17 | ||
| 18HF | OVHT SENS ELEMENT | 311 | 36-22-17 | ||
| 19HF | OVHT SENS ELEMENT | 311 | 36-22-17 | ||
| 20HF | CABLE ASSY | 311 | 36-22-17 | ||
| 84HF | OVERHEAT SENSING ELEM | 150 | 36-22-17 | ||
D. Pylon Section
| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 1HF1 | SNSG ELEM-OVHT, ENG 1 PYLON | 413 | 36-22-15 | ||
| 101HF1 | SENSING ELEMENT-OVHT, L PYLON LOOP B | 413 | 36-22-15 | ||
| 1HF2 | SNSG ELEM-OVHT, ENG 2 PYLON | 424 | 36-22-15 | ||
| 101HF2 | SENSING ELEMENT-OVHT, R PYLON LOOP B | 424 | 36-22-15 | ||
| 2HF1 | CABLE-CONNECTING, ENG 1 PYLON | 413 | 36-22-15 | ||
| 102HF1 | CABLE-CONNECTING, L PYLON LOOP B | 413 | 36-22-15 | ||
| 2HF2 | CABLE-CONNECTING, ENG 2 PYLON | 424 | 36-22-15 | ||
| 102HF2 | CABLE-CONNECTING, R PYLON LOOP B | 424 | 36-22-15 | ||
| 3HF1 | CABLE ASSY | 413 | 36-22-15 | ||
| 103HF1 | CABLE-CONNECTING, L PYLON LOOP B | 413 | 36-22-15 | ||
| 3HF2 | CABLE ASSY | 424 | 36-22-15 | ||
| 103HF2 | CABLE-CONNECTING, R PYLON LOOP B | 424 | 36-22-15 | ||
3. System Description
The aircraft leak detection system is divided into LH and RH zones by the crossbleed valve in the crossbleed duct at STA1537 (FR35). Each leak detection system operates independently.
The two wing/fuselage leak detection systems are made up of twin loops (A and B) of overheat sensing elements. This stop the possibility of incorrect warnings, due to an AND logic.
The overheat sensing elements are installed in each wing along the forward face of the front spar. Clamps and rubber grommets attach the overheat sensing elements at regular intervals along the full length.
In the fuselage, the elements are installed at STA1537 (FR35) and near the crossover bleed-air duct. They continue (LH side elements only) up to the APU check valve on the pressurized fuselage between STA2189 and STA2243.
One loop system is installed along the bleed air duct between the APU check valve and the APU bleed valve.
In each of the pylons, there are two loops. Each loop is located near the pylon ventilation duct.
** ON A/C NOT FOR ALL The aircraft leak detection system is divided into LH and RH zones by the crossbleed valve in the crossbleed duct at STA1537 (FR35). Each leak detection system operates independently.
The two wing/fuselage leak detection systems are made up of twin loops (A and B) of overheat sensing elements. This stop the possibility of incorrect warnings, due to an AND logic.
The overheat sensing elements are installed in each wing along the forward face of the front spar. Clamps and rubber grommets attach the overheat sensing elements at regular intervals along the full length.
In the fuselage, the elements are installed at STA1537 (FR35) and near the crossover bleed-air duct. They continue (LH side elements only) up to the APU check valve on the pressurized fuselage between STA2189 and STA2243.
One loop system is installed along the bleed air duct between the APU check valve and the APU bleed valve.
In each of the pylons, there are two loops. Each loop is located near the pylon ventilation duct.
4. Component Description
The overheat sensing elements have a solid nickel center conductor set in a ceramic insulation of porous aluminum oxide. An inconel tube contains these components and is sealed at the two ends. Eutectic salt fills the space between the tubing, the ceramic insulation and the center conductor. This mixture is compounded to give a signal at alarm temperature. For the wing and fuselage, the alarm temperature is 124 plus or minus 7 deg.C. The pylon alarm temperature value is 204 plus or minus 12 deg.C.
The impedance between the conductor and the outer tubing decreases suddenly when it gets to the level of the alarm temperature. At this temperature, the center conductor grounds and gives an alarm signal.
** ON A/C NOT FOR ALL The overheat sensing elements have a solid nickel center conductor set in a ceramic insulation of porous aluminum oxide. An inconel tube contains these components and is sealed at the two ends. Eutectic salt fills the space between the tubing, the ceramic insulation and the center conductor. This mixture is compounded to give a signal at alarm temperature. For the wing and fuselage, the alarm temperature is 124 plus or minus 7 deg.C. The pylon alarm temperature value is 204 plus or minus 12 deg.C.
The impedance between the conductor and the outer tubing decreases suddenly when it gets to the level of the alarm temperature. At this temperature, the center conductor grounds and gives an alarm signal.
5. Operation
The overheat sensing elements continuously monitor the surrounding areas for overheat conditions. They are connected in series and detect overheat conditions at one point along the length of the elements. When only a few inches of the elements are heated to the pre-determined temperature, an alarm is caused. When this occurs, the bleed air supply is shut off automatically.
If one loop does not operate (loop A or B), the remaining loop takes over. If there are leaks of the hot air from the bleed air duct and it heats an element of the operative loop, a signal is triggered.
The signal causes:
The different FAULT warnings on the AIR COND overhead panel 30VU are:
A functional test can only be done on the ground, by automatic control activation. It measures the outputs or status of each leak detection loop in-turn. The maintenance test lets the maintenance crew to check a specific function of the system. Additionally, the maintenance test finds defective Line Replaceable Units (LRU).
The two bleed air monitor computers (BMC1 and BMC2) monitor the seven detection loops (Loops A and B, LH wing, Loops A and B, RH wing, LH and RH pylon loops and fuselage loop). The indications are given in (Ref. AMM D/O 36-20-00-00).
The overheat sensing elements continuously monitor the surrounding areas for overheat conditions. They are connected in series and detect overheat conditions at one point along the length of the elements. When only a few inches of the elements are heated to the pre-determined temperature, an alarm is caused. When this occurs, the bleed air supply is shut off automatically.
If one loop does not operate (loop A or B), the remaining loop takes over. If there are leaks of the hot air from the bleed air duct and it heats an element of the operative loop, a signal is triggered.
The signal causes:
- The amber FAULT light on the AIR COND overhead panel to come on.
- The activation of the ECAM system.
- The MASTER CAUT lights on the panels 131VU and 130VU come on amber.
- One chime sounds.
- The message on the upper ECAM display unit comes on.
- The BLEED page on the lower ECAM display unit comes on.
The different FAULT warnings on the AIR COND overhead panel 30VU are:
- The FAULT legend on the ENG 1 BLEED pushbutton switch which comes on if there is an overheat condition in the LH zone (LH pylon, LH wing and LH MID fuselage),
- The FAULT legend on the ENG 2 BLEED pushbutton switch which comes on if there is an overheat condition in the RH zone (RH pylon, RH wing and RH MID fuselage),
- The FAULT legend on the APU BLEED pushbutton switch which comes on if there is an overheat condition in the MID and AFT fuselage (APU duct).
- The LH pressure regulating valve
- The LH wing anti-icing (if the wing anti-icing system is operative) valve
- The APU bleed valve (the APU pushbutton switch is in the ON position)
- The crossbleed valve (the selector is in the AUTO position).
- The RH pressure regulating valve
- The RH wing anti-icing valve (if the wing anti-icing system is operative)
- The crossbleed valve (the selector is in the AUTO position).
A functional test can only be done on the ground, by automatic control activation. It measures the outputs or status of each leak detection loop in-turn. The maintenance test lets the maintenance crew to check a specific function of the system. Additionally, the maintenance test finds defective Line Replaceable Units (LRU).
The two bleed air monitor computers (BMC1 and BMC2) monitor the seven detection loops (Loops A and B, LH wing, Loops A and B, RH wing, LH and RH pylon loops and fuselage loop). The indications are given in (Ref. AMM D/O 36-20-00-00).