DOC AIRBUS | AMM A320FEXHAUST - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
1. General
The APU exhaust system ducts the engine exhaust gas overboard. Its secondary function is to decrease the exhaust noise level. To keep aerodynamic losses during APU operation to a minimum, the duct has a sufficiently large diameter. Also, the exhaust system discharge is positioned at the very aft end of the aircraft, where a low pressure area is generated during flight. Thus it is also made sure that exhaust gas does not re-enter the APU air intake system.
** ON A/C NOT FOR ALL The APU exhaust system ducts the engine exhaust gas overboard. Its secondary function is to decrease the exhaust noise level. To keep aerodynamic losses during APU operation to a minimum, the duct has a sufficiently large diameter. Also, the exhaust system discharge is positioned at the very aft end of the aircraft, where a low pressure area is generated during flight. Thus it is also made sure that exhaust gas does not re-enter the APU air intake system.
2. Component Location
** ON A/C NOT FOR ALL 
APU Exhaust System - Component Location| ------------------------------------------------------------------------------- |
| FIN | FUNCTIONAL DESIGNATION | PANEL|ZONE|ACCESS | ATA |
| | | | | DOOR | REF. |
| ------------------------------------------------------------------------------- |
| EXHAUST MUFFLER ASSEMBLY 315/ 315AL/ 49-81-41 |
| 316/ 316AR/ |
| 317 317AL |
3. System Description
A. Muffler Assembly (Ref. 49-81-00)
The forward end of the muffler assembly is attached to the APU turbine flange. The rear extends through the access fairing 317AL into the airstream. The APU compartment aft fire wall (FR 84) has a cutout for the muffler assembly. The muffler assembly is held by rails which are part of the tailcone muffler compartment (Ref. AMM D/O 53-58-00-00).
The forward end of the muffler assembly is attached to the APU turbine flange. The rear extends through the access fairing 317AL into the airstream. The APU compartment aft fire wall (FR 84) has a cutout for the muffler assembly. The muffler assembly is held by rails which are part of the tailcone muffler compartment (Ref. AMM D/O 53-58-00-00).
B. Access Fairing Seal (Ref. 52-41-18)
The tailcone access fairing 317AL has a cutout for the muffler assembly rear end. The gap between the access fairing and the muffler assembly is sealed with a fireproof flexible seal. This prevents that exhaust gas enters the muffler compartment. This seal is permanently attached to the access fairing.
The tailcone access fairing 317AL has a cutout for the muffler assembly rear end. The gap between the access fairing and the muffler assembly is sealed with a fireproof flexible seal. This prevents that exhaust gas enters the muffler compartment. This seal is permanently attached to the access fairing.