2-15-15. Transmission Oil System.
Service the forward transmission, engine/combining trans-
mission, and aft transmission as follows:
Access to oil filler and location of sight gage of each
transmission (fig. 2-15-2) are as follows.
The oil filler and sight gage for forward trans-
mission are accessible within the hinged fairing on the right
side of the forward pylon. The filler neck is in the top forward
area of the transmission. The sight gage is located in the
bottom area below the filler neck; it can be viewed from
above and can also be seen through a viewing port in the
canted bulkhead at sta. 95 above the pilots seat.
The oil filler and sight gage for aft transmission
is on forward right side of the transmission sump. It is acces-
sible from the cargo ramp area.
The common oil filler for the combining trans-
mission and both engine transmissions is on the combining
transmission oil tank. It is accessible within the fairing of aft
pylon leading edge.
Refer to DA Form 2408-13-1 and table 2-15-1 for
the type of oil to use. Under normal conditions, the transmis-
sions shall be serviced with one type of oil only. If one type
of oil is in an transmission and that oil is not available, the
other type may be used in an emergency.
To prevent overfilling the engine and combin-
ing transmissions, check oil level within 30
minutes of shutdown. If the transmissions
have been shut down for more than 30 min-
utes, run the helicopter for a minimum of 5
minutes to verify oil level before servicing.
To prevent overfilling the forward and aft
transmission, check oil level after the aircraft
has been shut down for 30 minutes.
Fill the forward transmission, engine/combining and
aft transmissions to the FULL mark next to each sight
2-15-16. Hydraulic Systems Servicing.
2-15-17. Hydraulic Systems Fluid Servicing.
The utility systems and both flight control hydraulic systems
are serviced by a common fill module on the right side of the
helicopter above the ramp (fig. 2-15-2). The fluid level indi-
cators are on the MAINTENANCE PANEL above the fill
module. One indicator is for both flight control hydraulic
systems. The other indicator is for the utility system. Direct
level checks can also be made from the reservoir piston
rods. Service any system as follows:
Check the sight gage on the fill module reservoir for
fluid level. If fluid cannot be seen on the sight gage, fill the
Check the fluid level in the flight control reservoirs by
selecting each system at the FLT CONTR switch on the
MAINTENANCE PANEL. Then press the LEVEL
CHECK switch. Check the fluid level in the utility reser-
voir by pressing the LEVEL CHECK switch.
Turn the system select valve to the position for
the system to be serviced.
Using the handpump on the fill module, pump
fluid into the system until the fluid in the reservoir is at the
FULL mark. Keep the sight gage on the fill module full of
fluid by adding fluid to the reservoir as required.
Turn the system select valve to OFF.
2-15-18. Hydraulic Systems Accumulator Prechar-
Figure 2-15-3 depicts the relationship between proper
accumulator precharge and ambient temperature. To
check that an accumulator is properly precharged, read
free air temperature from the FAT gauge. Enter the bot-
tom of the chart at the indicated temperature and move
vertically to the pressure indicated on the accumulator
pressure gage. If the indicated pressure is within the
minimum and maximum limits, the accumulator is prop-
erly precharged. If the indicated pressure is not within
limits, refer to TM 55-1520-240-23 to service the accu-
2-15-19. Flight Controls Hydraulic Systems Accu-
The No. 1 flight control system accumulator is within the
forward transmission fairing, on the right side. The No. 2
system accumulator is within the aft pylon, on the right
side. Determine either accumulator precharge as fol-
Access to the respective accumulator.
Note precharge on accumulator and ensure is
within limits as per figure 2-15-3.
2-15-20. Utility System Accumulators.
There are five accumulators in the utility hydraulic sys-
tem. They provide pressure to start the APU, operate the
power brakes and swivel locks, and maintain line pres-
sure throughout the system.
The APU start accumulator is the largest in the
helicopter. It is mounted overhead in the ramp area at the
right of the aft transmission sump. The APU start module
accumulator is located aft and to the right of the APU start
accumulator. The utility reservoir pressurization (boot-
strap) accumulator is located forward of the No. 2 flight
control accumulator in the aft pylon, accessible through
the pylon right access panel. Determine accumulator
precharge as follows:
Depressurize the accumulator by turning
the handle on the UTILITY RESERVOIR DEPRESSU-
RIZE valve to OPEN. The valve is on the right side of the
cabin, in the cargo ramp area.