TM  1-1520-240-10            2-15-15 2-15-15.  Transmission Oil System. Service the forward transmission, engine/combining trans- mission, and aft transmission as follows: a. Access to oil filler and location of sight gage of each transmission (fig. 2-15-2) are as follows. (1) 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 pilot’s seat. (2) 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. (3) 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. b. 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. NOTE 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. NOTE To  prevent  overfilling  the  forward  and  aft transmission, check oil level after the aircraft has been shut down for 30 minutes. c. Fill the forward transmission, engine/combining and aft  transmissions  to  the  FULL  mark  next  to  each  sight gage. 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: a. Check the sight gage on the fill module reservoir for fluid level. If fluid cannot be seen on the sight gage, fill the reservoir. b. 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. c. Turn the system select valve to the position for the system to be serviced. d. 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. e. Turn the system select valve to OFF. 2-15-18.  Hydraulic  Systems  Accumulator  Prechar- ge. 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- mulator. 2-15-19.  Flight  Controls  Hydraulic  Systems  Accu- mulators. 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- lows: a. Access to the respective accumulator. b. Note  precharge  on  accumulator  and  ensure  is within limits as per figure 2-15-3. c. If servicing is required, refer to TM 55-1520-240-23. 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. a. 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: (1) 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.