A. Suspension System Capabilities
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The suspension system is designed 'fail-safe' with respect to the failure of any one of the 7 suspension rods or their respective structure attachment bracket or vibration isolator housing lug or clevis.
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The left forward vibration isolator is supported by 3 suspension rods (2 lug/clevis and one eyebolt/clevis joints) and is thus fixed in space. The right forward vibration isolator is supported by 2 rods (one lug/clevis and one eyebolt/clevis joint) such, that movement in the y-direction is possible. The aft mount is designed similarly, but allowing movement in the x-direction. This design approach permits production and installation tolerances in the APU as well as the suspension system to be washed out.
APU Suspension System - Component Location Figure 001 (SHEET 1)
R EFF : 106-106, 108-149, 211-299, 301-399, 49-12-00Page 2 Config-3 Aug 01/05
CES
APU Suspension System - Component Location Figure 001 (SHEET 2)
R EFF : 106-106, 108-149, 211-299, 301-399, 49-12-00Page 3 Config-3 Aug 01/05
CES
-The metallic components of the 3 APU mounts (one each vibration isolator and APU attachment bracket) are designed 'safe-life'.
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All other APU system interfaces are flexible to permit translational movement and rotational displacement of the APU in all directions. The actual APU movement occurring during APU and/or A/C-operation is much lower than the design limits. Only negligible loads are therefore transferred through these interfaces.
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All components of the suspension system are made of CRES with the exception of the tailcone structure brackets, which are made of titanium, and the elastomer component, which is made of a silicon elastomer compound.
-In case of fire in the APU compartment, the design of the vibration isolator core member and housing does not allow separation of these parts if the elastomer component is damaged or destroyed. Although the function of the vibration isolators will then be lost, the APU will settle only slightly.
B. Maintenance The entire suspension system is classified "ON CONDITION". Therefore, no regular maintenance tasks need to be carried out.
4. Component Description_____________________ (Ref. Fig. 001)
A. Suspension Rods 7 suspension rods of pre-adjusted and secured length support and position the APU. Their interfaces to the tailcone structure bracket clevises are designed as eye-bolts, thus allowing only axial loads to be transmitted. At the lower end they interface with the vibration isolators. On 4 suspension rods, these interfaces are designed as lug (on vibration isolator) and clevis (on suspension rod), thus completely fixing the APU in position and transmitting axial and torsional loads. The remaining 3 interfaces are of identical design as the upper 7 interfaces.
B. Vibration Isolators The function of the vibration isolators 4035KM, 4045KM and 4055KM is to mechanically isolate the APU from the A/C-structure in order to minimize the two-way transmission of vibration and shocks. Their main components are:
-a housing with lugs and clevises for the attachment of the suspension rods,
-an elastomer component within the housing to act as a mechanical isolator and
-a core member to provide a conical interface with the APU attachment bracket.
C. APU Attachment Brackets These brackets 4065KM, 4075KM and 4085KM are attached on the APU and provide a single point conical interface with the vibration isolator core member. Their design also assures the 6-degree nose-down APU installation position.
D. Electrical Bonding On both forward mounts, electrical bonding between the APU body and the tailcone structure is achieved by a bonding lead between the APU attachment bracket and the lower end of the most forward suspension rod body. At the upper end of the rod body, a bonding lead connects the rod to a bonding bracket on the tailcone structure. The other 5 suspension rods are connected identically to the tailcone structure.
APU MOUNTS ((GTCP 36-300)) - INSPECTION/CHECK
_____________________________________________ R **ON A/C 001-003, 051-099, 401-499,
TASK 49-12-00-210-001
Detailed Inspection of APU Suspension Rods, Vibration Isolator Structure incl.
Brackets and visible Part of Attachment Fittings (GTCP 36-300)
WARNING : DO NOT TOUCH THE APU UNTIL IT IS SUFFICIENTLY COOL TO PREVENT BURNS
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WHEN YOU DO THE MAINTENANCE TASK(S).
1.
Reason for the Job
__________________
Refer to the MPD TASK: 491200-01
2.
Job Set-up Information
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