Power Train (Transmissions)

Question 1

Power Train
Components

Answer 1

• Engine Transmission and
  Drive shaft (1 per side)
• Combining Transmission
• 7 forward synchronizing
  drive shafts
• 2 aft synchronizing drive
  shafts
• Synchronizing shafts joined
  by flexible couplings
• Forward Transmission
• Aft Transmission
• Aft vertical shaft (rotor
  shaft, only indications are
  on the maintenance panel).

Question 2

XMSN OIL PRESS LO cautions

Answer 2

• Total of 7
• ENG1, ENG2, FWD, COMB, AFT XMSN PRESS LO cautions illuminate when pressure
  drops below 20 psi.
• XMSN AUX PRESS LO caution illuminates when the fwd or aft transmission auxiliary oil
  pressure drops below 20 psi, or the combining transmission aux oil pressure drops below
  10 psi.
• AFT SHAFT PRESS LO caution illuminates when oil pressure drops below 10 psi.

Question 3

Aft vertical shaft

Answer 3

• Located inside the aft pylon
  in the top of the aft
  transmission.
• Transmits power to the
  rotor system from the aft
  transmission
• A thrust bearing and
  housing assembly is bolted
  to the aft pylon structure
  and carries the entire load
  of the aft rotor system.
• The support housing
  contains a single large ballbearing assembly lubricated by the aft transmission main
  oil system.

Question 4

Engine Transmissions

Answer 4

• Turn the direction of engine
  torque 90 degrees towards
  the combining transmission
• The two engine
  transmissions are identical
  and can be used in either
  position after only minor
  conversions

Question 5

Sprag Clutch

Answer 5

• One in each engine
  transmission
• Provides a positive drive
  connection to transmit
  power and permits
  freewheeling of both rotors
  when in an actual
  autorotation or simulated
  power fail.
• If NG fails to accelerate
  past 70% when advancing
  ECLs from GND to FLT,
  the sprag clutch most likely
  failed to engage

Question 6

Engine Transmission Oil System

Answer 6

• Check oil for Engine
  transmissions and
  combining transmission
  within 30 minutes of
  shutdown.
• Engine transmissions do not
  have auxiliary lubrication
  systems
• Oil Reservoir located above
  the combining transmission
  gear box.
• Engine transmission oil
  coolers mounted on the top
  of the reservoir. Cooled by
  a fan that pulls air through
  the coolers.

Question 7

Combining transmission
characteristics

Answer 7

• Combines the power of the
  engines and transmits it at a
  reduced shaft speed to the
  forward and aft
  transmissions
• Oil reservoir in same
  housing as the engine oil
  reservoir (see picture to
  right). Fluid level checked
  within 30 mins of shutdown
• Oil cooler directly below
  the No 1 Engine
  transmission cooler and is
  cooled by the same fan.
• The auxiliary oil reservoir
  located at the bottom of the
  cbox reservoir and is part of
  the main reservoir. It
  contains approx. 1 gallon of
  oil.
• The cooler fan is driven by
  the combining transmission

Question 8

Forward
transmission
characteristics

Answer 8

• No. 1 FLT hydraulic pump
  driven by fwd transmission
• 9 degree tilt fwd
• The main oil reservoir is
  located at the bottom of the
  transmission, and is
  constructed of Kevlar.
• Check oil levels after A/C
  has been shut down for 30
  mins.
• Reservoir sight glass is on
  forward side of transmission and can be checked through small access in sound proofing from the cockpit.
• Oil is cooled by air forced
  through the cooler by a
  transmission driven fan.
• Auxiliary oil comes from
  the main sump and is pulled
  by the auxiliary pump
  through the debris detection
  screen.
• Auxiliary pump provides up
  to 2 hours of safe operation
  if the main lubrication
  system becomes
  inoperative.
• If auxiliary oil pressure
  drops below 20 psi, the
  XMSN AUX PRESS LO
  caution will be displayed on
  the WCA, and in the
  caution field on MFD.
• The transmission with the
  low pressure is identified by
  a lit AUX PRESS LO
  indicating light on the
  MAINTENANCE PANEL

Question 9

Aft Transmission
Characteristics

Answer 9

• Two AC generators, the No.
  2 FLT hydraulic pump
  (mounted on No 1 side),
  and utility system pump
  (mounted on No 2 side)
  driven by the aft
  transmission
• 4 degree tilt fwd
• Check oil 30 min after A/C
  has been shutdown
• Oil reservoir made out of
  kevlar and located on the
  bottom of the transmission.
• The auxiliary oil also comes
  from the main sump, and is
  pulled by the auxiliary
  pump through the debris
  detection screen.
• Auxiliary pump provides up
  to 2 hours of safe operation
  if the main lubrication
  system becomes
  inoperative.