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Rev. A Sept 18, 2007 3-4 Transmissions Model S64F Helicopter.

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Presentation on theme: "Rev. A Sept 18, 2007 3-4 Transmissions Model S64F Helicopter."— Presentation transcript:

1 Rev. A Sept 18, Transmissions Model S64F Helicopter

2 3-5 Rev. A Sept 18, 2007 Main Gear Box

3 3-6 Rev. A Sept 18, 2007 F Main Gear box The main gearbox (M/G/B) is mounted behind the engines and changes the angle of drive from the engine to the main rotor head, and reduces the engine 9000 rpm. The main gearbox contains a four-stage gear reduction system to drive the main rotor head at a ratio of to 1 for a final main rotor speed of 185 rpm, and to drive the tail rotor head at 850 rpm

4 3-7 Rev. A Sept 18, 2007 F Main Gear Box Schematic

5 3-8 Rev. A Sept 18, 2007 F Main Gear Box A free wheeling unit at each MGB input allows for single- engine operation and auto-rotation. The accessory section, located at the rear of the transmission upper housing, contains mounting pads for A/C generators, rpm sensor, APU, and hydraulic pumps. A tail take-off (T.T.O.) gear in the transmission is coupled to the T.T.O. flange for tail rotor drive.

6 3-9 Rev. A Sept 18, 2007 Rear Cover Accessory System Schematic

7 3-10 Rev. A Sept 18, 2007 Right Hand Accessory The right hand accessory provides a location for additional hydraulic pumps to operate: 2 nd stage pump, Hoist pump and Auxiliary pump. The 2 nd stage hydraulic pump operates the primary flight controls. The hoist hydraulic pump pad operates additional equipment such as the auxiliary pump or the hoist pump.

8 3-11 Rev. A Sept 18, 2007 Right Hand Accessory Auxiliary Pump 2 nd stage Pump (24132 kPa) (20684 kPa)

9 3-12 Rev. A Sept 18, 2007 Free Wheeling unit The two 2 nd stage input pinion gears have a roller-ramp type clutch which permits the freewheel units in the gearbox to disengage the main rotor and tail rotor drive shafts when the relative main rotor rpm exceeds relative engine rpm such as during auto rotation, at engine shutdown, and single engine operation

10 3-13 Rev. A Sept 18, 2007 Free Wheeling Unit Assembly Clutch & Freewheel Housing

11 3-14 Rev. A Sept 18, 2007 Accessory Section Rear cover The main gearbox accessory section is located on the rear of the main gearbox. Mounted on the rear cover are the: 1.Number 1 and number 2 electrical generators. 2.The first stage hydraulic pump 3.The utility hydraulic pump 4.Oil Cooler pump 5.The tachometer Generator. 6.The A.P.U. Drive gear.

12 3-15 Rev. A Sept 18, 2007 Rear cover Accessory Section (1b) No 2 generator (1a) No.1 generator Oil filler (5) Tachometer (6) A.P.U. Input Tail Take off coupling (4) Oil Cooler Pump (3) Utility (2) 1 st stage Oil filter

13 3-16 Rev. A Sept 18, 2007 Rear Cover Accessory System Schematic

14 3-17 Rev. A Sept 18, 2007 Accessory Drive Notes Note: Tach. Generator (5), oil cooler pump (4), and the tail take-off coupling will not be operating during A.P.P. operations. Note: It is important to keep this operation to a minimum to reduce the possibility of damage or failure of freewheel rollers.

15 3-18 Rev. A Sept 18, 2007 Tail Take Off A tail take-off freewheel unit is incorporated in the rear cover accessory section of the main gearbox. When the auxiliary power plant (A.P.P.) is operating, the # 1 & 2 generators (1a & 1b), utility hydraulic pump (3), 1 st stage pump(2), and oil pump are operating; thus, providing the aircraft with electricity, hydraulics, and the main gearbox with oil flow. When the aircraft turbine engine(s) are operating and the main rotor is spinning at 185 revolutions per minute (rpm), the A.P.U. is no longer driving the accessory section. The accessory section is now being driven by the aircraft engine(s) through the main gearbox.

16 3-19 Rev. A Sept 18, 2007 Tail Take-off Assembly (T.T.O) Free Wheel Gear

17 3-20 Rev. A Sept 18, 2007 APU Drive Clutch Drive Shaft

18 3-21 Rev. A Sept 18, 2007 Auxiliary Power Unit The Auxiliary Power Unit (A.P.U.) provides temporary power for the aircraft. The A.P.U. drives the centrifugal type clutch assembly mounted on the lower aft section of the rear cover. The clutch couples the A.P.U. to the main gearbox by engaging when the A.P.U. is operating at approximately 75% and disengaging when the M/G/B speed (rpm) becomes faster than that of the A.P.U. The A.P.U. drives the accessory gear box at 8,000 rpm The tail take off is driven at 8,025 rpm by the MGB.

19 3-22 Rev. A Sept 18, 2007 Spline Warning The Spline adapters help eliminate gear spline wear and thus increase gear life. Spline adapters are inserted into many of the accessory drive gears. All hydraulic pumps that do not use spline adapters need to be removed from the main gearbox to grease the internal drive splines every Phase 4 (150 hrs.). Warning: Only use special tools to insert and remove adapters

20 3-23 Rev. A Sept 18, 2007 Spline adapter pictures The spline adapters (vespals) are made from phenolic plastic.

21 3-24 Rev. A Sept 18, 2007 Thomas Coupling The Thomas couplings are mounted between the engine drive shafts and input flanges of the main gearbox input housings. The Thomas couplings absorb engine torque and engine to gearbox vibrations. The Thomas couplings are dynamically balanced and must be replaced as an assembly. The outer three washers can be replaced if damaged or lost. All replacement washers must be the exact same weight.

22 3-25 Rev. A Sept 18, 2007 Thomas Coupling Heavy Mark Heavy Mark

23 3-26 Rev. A Sept 18, 2007 Thomas Coupling notes Any damage to the disks or other components of the coupling may cause excessive vibration and the coupling must be replaced. When replacing Thomas Coupling input flange use anti- seize on splines Thomas couplings and engine high-speed shafts will be identified with a residual heavy mark. It is important to remember to off set these marks 180 degrees (Or as close to 180º as possible.)

24 3-27 Rev. A Sept 18, 2007 MGB Lubrication Description Lubrication is accomplished by a self-priming wet sump system. The oil pump, attached to the main gearbox sump, circulates oil for main gearbox lubrication and cooling.

25 3-28 Rev. A Sept 18, 2007 F-Gear Box Lubrication Schematic

26 3-29 Rev. A Sept 18, 2007 Oil Filter and Strainer Description The gearbox has an oil filter and oil strainer or screen. A magnetic chip detector on the bottom of the sump and oil strainer assembly is part of the chip detector warning system. Note: F Model has an additional chip detector inside the oil strainer.

27 3-30 Rev. A Sept 18, 2007 Oil Filter The oil filter consists of a cover, bowl, bypass valve, and cartridge with filter elements. Filter elements can be bronze mesh or Monel mesh. Both are 40 micron nominal. It is mounted on the lower right side of the main gearbox accessory cover, and it filters all main gearbox oil between the oil pump and oil cooler.

28 3-31 Rev. A Sept 18, 2007 Oil Filter Installation

29 3-32 Rev. A Sept 18, 2007 Oil Filter Bypass If the filter becomes clogged, a bypass valve opens, allowing the oil to bypass the filter. The oil cartridge should be removed, and the filter elements should be cleaned and inspected every 150 hrs.

30 3-33 Rev. A Sept 18, 2007 Oil strainer Description A strainer in the lower part of the main gearbox consists of a sleeve, retainer, and screen. A chip detector is mounted inside the strainer. The strainer prevents large particles from entering the pump and causing damage. The strainer may be removed and inspected without draining the main gearbox by turning the outer sleeve 90º Note: The Strainer should be removed, inspected, and cleaned every 150 Hrs. with the oil filter.

31 3-34 Rev. A Sept 18, 2007 Oil Strainer Installation

32 3-35 Rev. A Sept 18, 2007 Oil Pump

33 3-36 Rev. A Sept 18, 2007 Oil Pressure Main Gear Box Oil is Mobil 626. The main gearbox oil pressure normal operating range is psi ( kPa). The oil pressure is adjusted at the oil pump which is located on the sump. A pressure transmitter located on the aircraft transmission deck sends an electrical signal to the Pressure Indicator located in the cockpit.

34 3-37 Rev. A Sept 18, 2007 MGB Pressure Transmitter Pressure Transmitter

35 3-38 Rev. A Sept 18, 2007 Oil Pressure Warning When oil pressure at the furthest point from the pump drops below psi ( kPa). the low oil warning switch on the main gearbox actuates, causing the caution trans oil press light to illuminate. The switch is located on the lower front right side at the lower MGB support.

36 3-39 Rev. A Sept 18, 2007 Oil Temperature The main gearbox temperature indicating system consists of an indicator, a resistance bulb located on the main gearbox sump, just after the oil screen, and circuit breakers. The temperature resistance bulb converts the temperature of the oil system to an electrical signal supplied to the trans oil temp indicator at the center of the instrument panel.

37 3-40 Rev. A Sept 18, 2007 Hot Oil Warning The main gearbox hot oil warning system consists of a caution panel capsule, (Trans Oil Hot ), temperature Plug Stat Switch, signal adapter unit, and a circuit breaker. The temperature Plug Stat Switch is located in the secondary manifold above the right hand input. The Temperature Plug Stat Switch actuates when oil temperature is over 121 ºC illuminating the caution-advisory panel Trans Oil Hot light. When the oil temperature drops below 121ºC the light will go off.

38 3-41 Rev. A Sept 18, 2007 Temperature Plug Stat Switch Temperature Switch Location

39 3-42 Rev. A Sept 18, 2007 Chip Detectors The electrical chip detectors provide an indication of metal accumulation in the main gearbox. The chip detectors are located on the bottom of the oil sump and in the strainer assembly. The two chip detectors are wired together in parallel.

40 3-43 Rev. A Sept 18, 2007 Chip Detector Diagram MGB Sump Chip Detector MGB Screen Chip Detector Caution Panel Press to Test On Left Main Gear Leg

41 3-44 Rev. A Sept 18, 2007 Oil Screen Chip Detector When enough conductive material bridges the contacts of the magnetic detector, a ground is provided, allowing current to actuate a relay that illuminates the Chip Main Trans light capsule on the caution- advisory panel.

42 3-45 Rev. A Sept 18, 2007 Types of Chip Plug Contamination Kind of MetalQuantity and/or SizeAction RequiredNotes SteelFine hair-like particlesNoneResult of normal wear (may have exaggerated appearance because of presence of oil). Particles in splinter or granular form. Do serviceability check. Replace gear box if necessary. Usually indicates failure. Tin, Lead, or CadmiumParticles not over inch thick ( mm). NoneComponent plating material only. Particles over inch thick ( mm). Do serviceability check. Aluminum or MagnesiumParticles in granular form.Do serviceability check.Result of using mallets and drifts during assembly. Copper or BronzeParticles in granular form.Do serviceability check.May indicate too much wear of thrust washers. PhenolicParticles in granular form.NoneResult of using mallets and drifts during assembly. SilverParticles in flake or splinter form NoneComponent Plating material only. Baked Resin CoatingTotal area of in. 2 ( mm 2 ) (i.e.) 0.25 in. (6.35mm) More than in. 2 ( mm 2 ) Do serviceability check. Remove gear box from service.

43 3-46 Rev. A Sept 18, 2007 Oil Cooler

44 3-47 Rev. A Sept 18, 2007 Oil Cooler The oil cooler has a thermostatic bypass valve, which will cause the oil to flow into the radiator core when the oil temperature exceeds 70 C. Also, oil will bypass the core if pressure exceeds 50 psi (345 kPa) differential. Note: Oil cooler assembly must be removed with the main gearbox if the M/G/B is removed for making metal.

45 3-48 Rev. A Sept 18, 2007 MGB Input

46 3-49 Rev. A Sept 18, 2007 Input Seal Replacement

47 3-50 Rev. A Sept 18, 2007 Rotor Brake

48 3-51 Rev. A Sept 18, 2007 Rotor Brake The rotor brake is a hydraulic disc-type rotor, which has replaceable brake linings (pucks). The rotor brake housing is mounted on the left side of the main gearbox with the brake disc rotating through it. The rotor brake is capable of stopping the main rotor in about 45 seconds from 100% NR with both engines shut-off. The hand pump lever to activate the brake is located in the cockpit overhead.

49 3-52 Rev. A Sept 18, 2007 Rotor Brake Rotor Brake Assemble Rotor Brake Disc

50 3-53 Rev. A Sept 18, 2007 Rotor Brake Shaft Seal A face-type (carbon) seal is used the rotor brake shaft. The carbon seal consists of two matched components: the seal assembly and the seal mating ring. The mating surfaces of the carbon element and the ring are lapped to extremely close fit, providing the sealing action.

51 3-54 Rev. A Sept 18, 2007 MGB Operational Check New, overhauled or repaired main gearboxes receive a full load run-in at the factory and require no further break-in run. However, an operational check is required in addition to the pilot pre-flight check to ensure proper installation and that the lubrication system is working properly.

52 3-55 Rev. A Sept 18, 2007 Allowable Leakage Leaking from the main gearbox may be caused by worn or poorly installed seals, gaskets, or shims. Total oil leakage from all sources must not exceed a drop in oil level on the dipstick from full to midway between Full and Add in 10 flight hours. Note: Oil level should be checked 30 minutes after engine or A.P.U. shutdown.


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