234 Drive System

Question 1

234 Drive System Overview

Answer 1

5 transmissions
2 engine transmissions
Combining Transmission
Aft and forward Transmissions

7 forward synch shafts

2 aft synch shafts

Vert shaft

Fan drive shaft

Question 2

Lubrication and cooling

Answer 2

Each transaction has its own separate main lube system and aux lube system.

Four oil coolers in the aft pylon, lower front (forward transmission), upper front and farthest aft (combining and engine) upper forward (aft transmission).

Question 3

C-Box/ Engine XMSN Primary and Aux Pumps

Answer 3

A 6 element pump (3 pressure pumps, 3 scavenge pumps) and 3 aux pumps are driven by an accessory drive shaft.

Question 4

C-Box

Answer 4

Combines inputs from ETs and transmits outputs to fore and aft transmissions.

Three section reservoir for ET 1, C-Box, ET 2 respectively.

Drives 9 pumps for lubing C-Box and ETs. 3 main pressure, 3 main scavenge, 3 aux.

Question 5

Oil Pressure/Temperature Sensor Switches

Answer 5

Each of the 5 have a pressure transducer and temp bulb connected to a pressure and temp rotary switches.

The transmission can be selected and condition indicated on the corresponding gauges. Or, by selecting scan, the closest to limits shown.

Question 6

XMSN OIL PRESS annunciator

Answer 6

Five pressure switches, one in each transmission, will eliminate the shared XMSN OIL PRESS light.

Question 7

XMSN OIL HOT

Answer 7

Five thermal switches, one for each transmission, will illuminate the XMSN OIL HOT light when temps reach 140 degrees C. Forward and aft are in the sump, C-Box and ETs are in the oil line before the cooler.

Question 8

XMSN AUX PRESS light

Answer 8

Pressure in the aux system of one of the 5 has dropped below 10psi. Maintenance panel must be consulted to determine which one.

Question 9

Engine Transmissions

Answer 9

Mounted to the front of the engine.

Receives N2 output power through the quill shaft.

Torque changed 90 degrees

Sprag clutch on output shaft

Main and aux pressure pumps and scavenge pumps located on and driven by C-Box.

Question 10

Forward Transmission

Answer 10

9 degree tilt forward. Accessory drive turns main and aux lube pumps and rotor tach gen.

Rotor tach gen mounted on main lube pump

Chip detector located in the sump illuminates the XMSN CHIP annunciator.

Question 11

Main Lube Drop of Oil

Answer 11

Sump,
pump (with bypass),
main filter (with bypass),
overtemp switch,
cooler (with thermostatic bypass valve), jet protection screen,
pressure transducer,
low pressure switch,
jets,
temp bulb in sump (gauge), chip detector in aux sump

Question 12

Aux Lube Drop of Oil

Answer 12

Aux sump,
Aux pump (with bypass),
Aux filter,
Aux low pressure switch (XMSN AUX PRESS at 10psi)
Jets (limited),
Temp bulb (in sump),
Chip detector (in sump)

Question 13

Aft Transmission Drop of Oil

Answer 13

Sump
Screen
Pressure pump (bypass)
Main filter (with bypass and LRB)
Overtemp switch (XMSN OIL HOT light)
Cooler (with thermostatic bypass)
Jet protection screen
Pressure transducer (for the gauge)
Main low pressure switch (XMSN OIL PRESS light)
Jets
Thrust bearing filter
Thrust bearing jet
Thrust bearing chip detector (XMSN CHIP light)
Chip detector in aux sump (XMSN CHIP light)

Pressurized oil is also supplied to the AGB and oil cooled generators.

Question 14

AGB

Answer 14

The accessory gear box is driven by the aft transmission and utilizes a sprag clutch for for operation of the AGB with rotors stopped.

Components driven by the AGB are:

Aft transmission lube pump
Two flight control hydraulic pumps
Two AC generators
The utility hydraulic pump
Two generator scavenge pumps
And the AGB motor

Question 15

Other accessories driven by the aft transmission