(e)
FR84 Fire Wall Seal A circumferential fireproof seal is installed on a bracket on the muffler substructure. It seals the gap between the fire wall cutout in FR84 and the exhaust muffler assembly.
R EFF : 001-049, 101-105, 107-107, 151-199, 49-81-00Page 4 201-210, Config-2 Aug 01/05
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(2)
Hot Nozzle Assembly This component is directly attached to the APU turbine flange with a V-clamp. It is in contact with the tail pipe assembly through the piston ring and the muffler body through the externally installed bellows. APU movement is not transmitted to the muffler assembly. A drain port is installed at the lowest point (Ref. 49-17-00).
(3)
Bellows It is the flexible connection between the hot nozzle and the muffler body. It is also a back-up seal to prevent exhaust gas leakage into the APU compartment. It is attached to both items with band clamps. It allows movement between the APU and the muffler body.
(4)
V-Clamp Insulation Segments To make sure that the surface temperature does not exceed 232 Deg. C, the connection between the APU turbine flange and the hot nozzle assembly is insulated. Two half-circle insulation segments cover the interface, held in position with lockwire fastened to the buttons on these items.
B. Muffler Assembly Installation Support rails align the assembly with the APU. Longitudinal positioning is provided at the rear attachment brackets only. Lateral positioning is made by fixing the assembly to the left rail. The distance between the rails is 6mm larger than the distance between the muffler assembly attachment brackets. Thus the muffler assembly is positioned 3mm to the left of the APU longitudinal axis. The attachment at the right rail allows for thermal expansion differences. The 3mm displacement is taken up at the muffler assembly/APU turbine flange interface by the bellows and the sealing ring.
4. Operation
_________
APU operations cause thermal expansion of the muffler assembly:
-Radial expansion: This causes the muffler to expand approx 6mm in diameter This expansion is taken up through the 6mm gap allowed at the mounting rail and the compression of the seals
-Forward axial expansion: This leads to a reduction of the distance between the muffler assembly and the APU. This is taken up internally by the sealing ring moving within the flange. The bellows compress to take up the expansion.
-Rearward axial expansion:
The muffler gets longer and the compression is taken up by the rear
fairing seal.
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APU Exhaust Muffler Assembly - Major Components
Figure 002 (SHEET 1)
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APU Exhaust Muffler Assembly - Major Components
Figure 002 (SHEET 2)
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EXHAUST SYSTEM - DESCRIPTION AND OPERATION
__________________________________________
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.
All components in contact with exhaust gas are made of corrosion resistant materials. All components exposed to high temperatures are made of fireproof or fire resistant materials. A flexible connection allows for relative movement between the APU and the muffler assembly and allows for any vibration and inertia loads during operation. Drainage provisions are incorporated into the muffler assembly. One ventilation louver each at the top and the bottom of the muffler compartment limit the structure temperature to 110 deg. C max. (Ref. 53-58-00). Muffler assembly surface temperature does not exceed 232 deg. C.
2. Component Location
__________________
(Ref. Fig. 001)
-------------------------------------------------------------------------------FIN | FUNCTIONAL DESIGNATION | PANEL|ZONE|ACCESS | ATA | | | | DOOR | REF. -------------------------------------------------------------------------------
EXHAUST MUFFLER BODY 315/ 315AL/ 49-81-41 316/ 316AR/ 317 317AL
HOT NOZZLE ASSEMBLY 315/ 315AL/ 49-81-42 316 316AR BELLOWS 315/ 315AL/ 49-81-42 316 316AR V-CLAMP INSULATION SEGMENTS 315/ 315AL/ 49-81-41 316 316AR
APU Exhaust Muffler Assembly Installation
Figure 001 (SHEET 1)
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APU Exhaust Muffler Assembly Installation
Figure 001 (SHEET 2)
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