ACCESSORY DRIVE GEARBOX - DESCRIPTION AND OPERATION
___________________________________________________
1. General
_______ The cast-aluminum accessory-drive gearbox (referred to as the gearbox) has the drive pads for the Auxiliary Power Unit (APU) generator and accessories which include:
-
the starter motor assembly,
-
the oil pump module,
-
the fuel control unit (FCU),
-
the cooling-air fan assembly.
2. Component Location
__________________
(Ref. Fig. 001)
-------------------------------------------------------------------------------FIN | FUNCTIONAL DESIGNATION | PANEL|ZONE|ACCESS | ATA | | | | DOOR | REF. -------------------------------------------------------------------------------VALVE REGULATING - GEARBOX 315 315AL 49-26-53
3. Description
___________ The gearbox is designed as a module. You can remove it from the APU leaving all the gears, bearings and seals in position. The gearbox is of a low weight design with improved gear lubrication and is fitted with a heater to aid start reliability. A flanged joint attaches the gearbox to the load compressor. The APU gives a direct drive to the gearbox. The APU forward side mounts are part of the gearbox structure, which is also an oil reservoir (for the wet-sump lubrication system) (Ref. 49-90-00). The capacity of the oil reservoir is
6.26 l (1.6537 USgal). The gravity fill port is part of the gearbox housing. A direct-reading sight glass, installed adjacent to the gravity fill port, gives a visible oil-level indication. An oil level switch, installed in the sump, gives minimum oil-level indication signals to the Electronic Control Box (ECB) 59KD (Ref.
The gearbox is of the nonpressurised type. All the accessories mounted on the APU gearbox are approved by the APU manufacturer's type certification. This meets the requirements of JAR 25A 1011, 1163 (a) and 25B 1163. Accessory Drive Gearbox
4. Operation
_________ The gearbox contains the oil that is used to lubricate the components of the APU. Oil is drawn from the gearbox by a pump and passed to the oil cooler. From the oil cooler, the oil is passed to the various components. The gearbox also contains two filters, each fitted with a pressure relief valve to prevent excessive pressure if the filters become blocked.
R EFF : 001-049, 101-105, 107-107, 151-199, 49-26-00Page 1 201-210, Config-2 Aug 01/05
CES
Accessory Drive Gearbox
Figure 001
CES
ACCESSORY DRIVE GEARBOX - DESCRIPTION AND OPERATION
___________________________________________________
1. General
_______ The cast-aluminum accessory-drive gearbox (referred to as the gearbox) supplies the drive pads for the Auxiliary Power Unit (APU) generator and accessories which include:
-
the starter motor assembly,
-
the oil pump assembly,
-
the fuel control assembly,
-
the cooling-air fan assembly.
2. Description
___________ (Ref. Fig. 001, 002) A flanged joint attaches the gearbox to the load compressor. The APU gives a direct drive to the gearbox. The APU forward side mounts are part of the gearbox structure, which is also an oil reservoir (for the wet-sump lubrication system) (Ref. 49-90-00). The capacity of the oil reservoir (gearbox) is 5.4 l (1.43 USgal). The gravity fill port is part of the gearbox housing. A direct-reading sight glass, installed adjacent to the gravity fill port, gives a visible oil-level indication. An oil level sensor, installed in the sump, gives a low oil-level signal to the Electronic Control Box (ECB) 59KD (Ref. 49-93-00) if the oil in the reservoir has decreased to 3.9 l (1.03 USgal) or less. Air/oil mist is vented to the APU exhaust through a passage in the gearbox housing downstream of te air-oil separator. A vane type pressure pump provides the pressurized oil for lubrication and generator cooling. A non-adjustable, spring loaded pressure relief valve is installed on the lower front face of the gearbox. It is set to open when the oil pump pressure exceeds 4.5 to 5.2 bar (66 to 76 p.s.i.).
The accessory drive gearbox is a module. You can remove it complete from the APU, which lets all the gears, bearings and seals remain in position.
Accessory Drive Gearbox
Figure 001
CES
Gearbox - Description
Figure 002
CES VALVE SHUT-OFF GEARBOX - PRESSURE - REMOVAL/INSTALLATION
________________________________________________________ R **ON A/C 001-003, 051-099, 401-499,
TASK 49-26-51-400-001 Installation of the Gearbox-Pressurization Solenoid Valve (GTCP 36-300) WARNING : DO NOT TOUCH THE APU UNTIL IT IS SUFFICIENTLY COOL TO PREVENT BURNS
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