7. Main Rotor Head
Model S64F Helicopter
Rev. A Sept 18, 2007 4-

8. Main Rotor Head The MRH is fully articulated
The MRH is made up of two principal components the hub and the Swashplate.
The hub consists of an upper and lower plate, hinge assemblies, sleeve and spindle assemblies, and six pressurized dampers.
The Swashplate consists of a rotating disc and stationary disc connected together.
Other components of the head are anti-flapping restrainers, adjustable pitch control rod assemblies, and rotating and stationary scissors.
Rev. A Sept 18, 2007 4-

9. Main Rotor Head
Hub
Swashplate
Rev. A Sept 18, 2007 4-

10. Main Rotor Head
The Swashplate and control rods permit movement of flight controls to be transmitted to the blades.
The hinge assemblies allow the blades to lead, lag, and flap.
The sleeve and spindle assemblies allow each blade to be turned on its span wise axis to change blade pitch.
The dampers prevent damage to the head by absorbing blade loads during rotor operation
Rev. A Sept 18, 2007 4-

11. Main Rotor Head Sleeve & Spindle Hinge Assembly Damper Control Rod 4-
Rev. A Sept 18, 2007 4-

12. Main Rotor Head
The anti-flapping restrainers restrict flapping motion of the blades when the main rotor head is slowing or stopped.
The rotating scissors are connected to the rotating Swashplate and to the lower plate of the hub.
The stationary scissors are connected to the stationary Swashplate and the main gearbox upper housing.
Rev. A Sept 18, 2007 4-

13. Main Rotor Head Rotating Scissors Stationary Scissors 4-
Rev. A Sept 18, 2007 4-

14. Main Rotor Head Lubrication
The sleeve and spindle assembly receives lubrication from the individual oil reservoir mounted on the upper plate above the horizontal hinge pin.
The oil lubricates the spindle bearings through an external tube from the horizontal hinge pin housing.
Centrifugal force and gravity feed the oil into the spindle.
Rev. A Sept 18, 2007 4-

15. Oil Reservoirs
Reservoirs (6)
Rev. A Sept 18, 2007 4-

16. Controls
Primary servo inputs are sent to the MRH through the Swashplate.
The PC links connect the Swashplate to the pitch horn on the sleeve and spindle.
Stationary and Rotating scissors help to keep their perspective Swashplate stable.
Each MRB has a damper which allows it to lead and lag.
Rev. A Sept 18, 2007 4-

17. Controls Damper Rotating Scissors Control Primary Servo Rod Stationary
Rev. A Sept 18, 2007 4-

18. Swashplate The Swashplate has two halves; stationary and rotating.
The stationary Swashplate attaches to the primary servos and transfers inputs to the rotating Swashplate.
The rotating Swashplate rotates with the rotor head and transfers inputs from the stationary Swashplate to the pitch horn.
The Swashplate assembly pivots around the drive shaft on the uniball.
Rev. A Sept 18, 2007 4-

19. Stationary Swashplate
Rotating Swashplate
Spherical Bearing
Stationary Swashplate
Rev. A Sept 18, 2007 4-

20. Control Rods
The adjustable control rods extend from the sleeve and spindle horn assembly to the rotating Swashplate.
The bearings are allowed inch (.33 mm) play or a combined allowance of inch (.533 mm).
Blade pitch adjustments are made at the PC link, each notch on the PC moves the blade path about ½ inch (1.27 cm).
Adjustment notches
Rev. A Sept 18, 2007 4-

21. Rotating & Stationary Scissors
The rotating scissor assemblies are bolted between the lower plate of the main rotor hub and rotating Swashplate. They cause the rotating Swashplate to rotate with the main rotor hub.
The stationary scissors connect the stationary Swashplate to the main gearbox. They prevent the stationary Swashplate from turning with the main rotor head.
Rotating
Scissors
Stationary Scissor
Rev. A Sept 18, 2007 4-

22. Droop & Flap Restrainers
The droop and flap restrainers are spring loaded in the locked position and are disengaged with centrifugal force.
They restrict drooping and flapping of blades when the MRH is slowing down or static.
Droop
Restrainers
Anti-flapping
Assembly
Rev. A Sept 18, 2007 4-

23. Damper Description
The dampers are mounted between the upper and lower plates of the MRH to slow hunting of blades during rotation and to absorb rotor engagement loads.
Damper Mounts
Rev. A Sept 18, 2007 4-

24. Damper Description
The dampers are pressurized with hydraulic fluid from an accumulator installed in the main rotor shaft.
Constant pressurization allows the damper piston shaft to be fully extended at all times except when main rotor loads cause the fluid to be bypassed internally, causing the shaft of the piston to withdraw into the damper.
Rev. A Sept 18, 2007 4-

25. Damper System
From Accumulator
Rev. A Sept 18, 2007 4-

26. Damper Accumulator
The damper accumulator is serviced with nitrogen to maintain a constant hydraulic pressure to the dampers.
A visual indicator rod in the top of the accumulator indicates proper hydraulic pre-charge.
The pressure gauge and servicing valve for the accumulator are on the support ring of the main rotor head fairing.
Rev. A Sept 18, 2007 4-

27. Damper Accumulator Installation
Nitrogen Pressure
Indicator
Accumulator
Rev. A Sept 18, 2007 4-

28. Accumulator Charging
From time to time the damper accumulator hydraulics will need to be recharged.
The indicator pin on top of the accumulator indicates servicing required.
The hand pump on the sled is used to pump hydraulic fluid from the utility reservoir into the accumulator.
As hydraulic fluid is pumped into the accumulator the indicator pin will go down.
Hand Pump for
Accumulator
Rev. A Sept 18, 2007 4-

29. MRH Installation
Prior to installing the MRH inspect the vertical shaft splines and split cone seat.
Inspect threaded relief grove for cracks with 5x magnifying glass. If baked resin coating is present no inspection is required.
Master
Splines
Split Cone Seat
Relief Groove
Rev. A Sept 18, 2007 4-

30. MRH Installation
The main gear box shaft has a 3º tilt. When removing or installing the MRH this tilt should be removed by filling the nose strut and left hand gear leg with nitrogen.
The main rotor head is held onto the shaft by a set of split cones, a retaining nut and a pressure plate.
Rev. A Sept 18, 2007 4-

31. Torque Procedure
The pressure plate bolts and retaining nut bolts are numbered on both the top and bottom of the MRH.
Torque retaining nut bolt assemblies to 1045 inch-pounds (87 foot-pounds, 118 Nm.) in increments of 200 inch-pounds (26 Nm.); in the order of etched numbers on retaining nut, until they stabilize.
Retaining
Nut
Bolts
Retaining Nut
Rev. A Sept 18, 2007 4-

32. Torque Procedure
Torque the pressure plate bolts to inch- lbs (200 foot-lbs, 271 Nm.) in 1000 inch-lbs (113 Nm.), increments with the final torque a inch-lbs (281 foot- lbs, 383 Nm.) in the order of numbers on pressure plate, until they stabilize.
Recheck retaining nut bolt torque, if any bolt slips torque all bolts in sequence to 1045 inch- pounds (118 Nm.).
Rev. A Sept 18, 2007 4-

33. Torque Procedure
After installing Main Rotor Blades check torque on the retaining nut bolts again. If they move torque top and bottom again as per maintenance manual.
After 10 hours of flight a torque check of both retaining nut and pressure plate is due and is repeated at 10 hour intervals until the head torque stabilizes.
After 3 torque checks the head must be removed and reinstalled after inspecting condition of cones, cone seats, pressure plate and retaining nut.
When removing MRH the torque should be broken in the same increments as the installation.
Rev. A Sept 18, 2007 4-

34. MRH & MGB Installation
The MRH and MGB can be installed as an assembly.
Rev. A Sept 18, 2007 4-

35. Tail Rotor Head
The tail rotor head on the S64F is a semi-articulated head. Each blade can flap individually, and each blade can be rotated on its sleeve and spindle for pitch change.
The tail rotor head is a four bladed system. Each blade has a sleeve and spindle, a pitch change link and tubing attaching to a central reservoir.
The tail rotor p/c links receive their input from the tail rotor head servo which is mounted on the opposite side of the tail rotor gear box from the tail rotor head.
Rev. A Sept 18, 2007 4-

36. Tail Rotor Head Hub Sleeve & Spindle Flap Restrictor Oil Reservoir
Pitch change link
Rev. A Sept 18, 2007 4-

37. Anti-Flapping Plunger
The anti-flapping plunger, installed in the center of the spindle, prevents excessive blade flapping in flight and locks the blades when slowing down or static.
Centrifugal force causes the plunger to compress the dual spring and allow the blades to flap.
The plunger is fully retracted at 50%-60% Nr allowing a 10º plus or minus flapping range.
Rev. A Sept 18, 2007 4-

38. Anti-Flapping Plunger
When the plunger is fully retracted it still contacts the lugs at their outer range. This allows the blades to flap plus or minus 10º.
Lug
Hub
Plunger
Plunger Seen in Static Position, Blade Locked
Rev. A Sept 18, 2007 4-

39. Tail Rotor Head Controls
The tail rotor controls are supported by the tail rotor head. The controls consist of a pitch beam and four pitch change links.
The pitch beam is mounted on the tail gearbox pitch control shaft.
Flight control movement through the tail rotor servo cylinder moves the pitch control shaft in and out.
Pitch beam movements are then transferred to the sleeves of the tail rotor head, through the pitch change links thus changing blade pitch.
The adjustable links provide the means to set blade angle for flight control rigging.
Rev. A Sept 18, 2007 4-

40. Tail Rotor Head Controls
Pitch
Change
Beam
PC Link
Tail Rotor
Gearbox
Reservoir
Rev. A Sept 18, 2007 4-

41. Tail Rotor Head Installation
The Tail Rotor head is held onto the tail gear box shaft by a set of split cones, a pressure washer, a retaining nut and a lock ring.
The TRH is aligned on the tail gear box shaft by a master spline like the MRH.
INSTALL
Solid split cone
Tail rotor head on spline
Split cones (verify s/n for matched set)
Pressure washer
Retaining nut (hand tight)
Lock ring
Rev. A Sept 18, 2007 4-

42. Tail Rotor Head Split Cones Pressure Split Cones Washer Pitch Change
Beam
Retaining
Nut
Lock Ring
PC Link
Rev. A Sept 18, 2007 4-

43. Installation
The torque for the TRH is similar to the MRH. The bolts are torqued in sequence as indicated on the lock ring.
The bolts are brought up to torque in steps. The bolts should be torqued in sequence until they stabilize and then move on to the next torque value.
The jam nuts are torqued last. Then all the bolts are safe-tied in pairs.
Rev. A Sept 18, 2007 4-

44. Purging TRH
The TRH assembly comes from the manufacture with the air already purged. Verify that there is some oil in the reservoir prior to installing.
If purging is required lay the TRH horizontal and pump oil through the sleeve and spindle into the reservoir until no air bubbles are seen. Repeat on remaining sleeve and spindle assemblies.
Purge Point
Rev. A Sept 18, 2007 4-