Mod 6 Free wheels and clutches Flashcards
Type of aircraft that need a clutch.
Direct turbo - shaft turbine
Piston engine
A manual clutch is engaged by
The Pilot
A helicopter with two free-turbine engines (such as a Bell 212 or Eurocopter AS355) will have:
No clutch and two freewheels
The freewheel unit on a Bell 206 is mounted on the engine; however it is lubricated by the transmission. Why?
In case of an engine failure, the freewheel unit wont run out of lubrication.
The dual tach on a piston engine powered helicopter would indicate:
Engine speed Rotor speed (Nr)
What system allows the transmission speed to exceed the speed of the engine?
Freewheel unit
location of the freewheel on helicopters without clutch
is located right after or downstream of the engine
Location of a freewheel on helicopter with clutch
right after downstream of the clutch
types of freewheels units
Ramp and roller type
sprag assembly
freewheels lubrication types
internal or self contained
external (main gearbox)
different names for a freewheels
Bell Freewheeling unit or Freewheeling Assembly
Hughes / McDonnell Douglas Overrunning Clutch
Robinson Sprag Clutch
Eurocopter & Turbomeca Free Wheel
freewheel is used on a helicopter to allow the engine
to drive the rotor system, however prevent the rotor system from driving the engine.
clutch purpose
unload the engine during start
allows the engine to be disconnected from the drive train.
clutch location
Typically, the clutch can be found in the drive line right after the engine, however before the freewheeling unit.
Automatic Clutches are grouped into two categories
Wet:A wet clutch is one that runs in oil. Oil is used to provide cooling. the clutch run in oil from the transmission.
Dry:A dry clutch uses air for cooling.
manual clutch need lubrication ?
no, Manual clutches using belts require no lubrication on the belts. The belts should be kept clean and dry.
Why The pilot must engage the clutch system as soon as possible after engine start
to prevent excess wear on the belts and sheaves.
types of gearbox
main rotor gearbox
tail rotor 90 gear box
intermediate 42 gearbox
combining gearbox (multiengine)
main gear boxes are?
speed decreasing
The most common power limitation in a helicopter is due to
main gearbox limitations
tail rotor gearbox is most but not all
are speed decreasing
intermediate gear box
Little or no change in speed, only a change in direction
combining gear box
Used on Multi-engine helicopters. Combine the output of two (or more) power plants into a single output
the pylon on R22 and bell 206 includes ?
mast
main rotor
main gearbox
the pylon must?
support the weight of the helicopter
manage the vibration from the main rotor
manage movement between the rotor and air frame
Bell 206 MRGB includes ?
pin drag pin assembly ( spike mount)
Pylon support links (A frame)
insulation mount
free turbine engine what is N1 or Ng?
Gas Producer Speed”
–The speed of the Compressor and Gas Produce Turbine wheels(often reads in percent)
Free turbine engine what is N2 or Nf
Free Turbine Speed” –The speed of the “Free” or “Power” Turbine(often reads in percent)
exhaust gas temperature gauge
EGT, TOT, ITT, T4
inter-turbine temperature (ITT),
exhaust gas temperature (EGT),
turbine outlet temperature (TOT).
Torquimeter
gauge often reads in PSI or percent
Engine air filtration
Barrier type filter Particle Separate ( centrifugal swirl tubes) Turbine
Coupling function
Allow for movement between drive train components.
Coupling types
Flexible (Thomas, Bendix, K-flex)
Greased (Bell 206 engine to transmission, and Bell Medium tail rotor drive )
