Powertrain Flashcards
Power Train Components Overview
Power Train Components Overview
(1) The helicopter drive system includes five transmissions; No. 1 and No. 2 engine transmissions, combining transmission, forward transmission, and aft transmission. Transmissions are connected by the two engine drive shafts, and nine synchronizing shafts
(2) The synchronizing shafts are separated into seven forward synchronizing shafts (1-7) which drive the forward transmission and two aft synchronizing shafts (8 and 9) that drive the aft transmission
(3) The aft vertical shaft extends out of the top of the aft transmission and is used to turn the aft rotor head
The left side of the maintenance panel is setup for the power train system. This area will alert the flight engineer (FE) and/or crew chief (CE) when problems arise in the power train system
The Warnings Cautions and Advisory (WCA) page will alert the pilots when problems arise with the power train system. The caution and advisory summary page list the active cautions on the left side
(a) There are a total of seven transmission oil pressure low cautions:
The Warnings Cautions and Advisory (WCA) page will alert the pilots when problems arise with the power train system. The caution and advisory summary page list the active cautions on the left side
(a) There are a total of seven transmission oil pressure low cautions
1) The oil pressure low cautions cover the main oil pressures for the ENG1, ENG2, FWD, COMB, AFT transmissions. The cautions also cover the auxiliary pressures for the FWD, COMB, and AFT transmissions. There is also a caution for the AFT SHAFT
2) The ENG1, ENG2, FWD, COMB, and AFT XMSN PRESS LO cautions illuminate when that transmission oil pressure drops below 20 psi
3) The XMSN AUX PRESS LO caution illuminates when the FWD or AFT transmission auxiliary oil pressure drops below 20 psi, or the COMB transmission auxiliary oil pressure drops below 10 psi
4) The AFT SHAFT PRESS LO caution illuminates when its oil pressure drops below 10 psi
There are a total of five transmission oil hot cautions
There are a total of five transmission oil hot cautions
1) The OIL HOT cautions cover the ENG1, ENG2, FWD, COMB, and AFT transmissions
2) The OIL HOT cautions for the transmissions illuminate when that transmissions oil temperature rises above 140 degrees Celsius
There are six transmission chip cautions
There are six transmission chip cautions
1) The cautions cover the FWD, COMB, and AFT, No.1 and No.2 ENG transmissions and the AFT vertical shaft
2) The cautions will illuminate when ferrous material has bridged the gap on the chip detector for one of these components
There are a total of six debris screen cautions
There are a total of six debris screen cautions
1) The DEBRIS cautions cover the FWD, COMB (LH and RH), AFT, No.1 and No.2 engine transmissions
2) The caution will illuminate when conductive material bridges the gap on the forward transmission, aft transmission, combining transmission, No.1 engine transmission or No. 2 engine transmission debris screen
The Warnings Cautions and Advisory (WCA) page will alert the pilots when problems arise with the power train system. The caution and advisory summary page list the active advisories on the right side
a. There is a total of five transmission oil pressure hi advisories
The Warnings Cautions and Advisory (WCA) page will alert the pilots when problems arise with the power train system. The caution and advisory summary page list the active advisories on the right side
a. There is a total of five transmission oil pressure hi advisories
1) The oil pressure hi advisories cover the main oil pressures for the ENG1, ENG2, FWD, COMB, AFT transmissions
2) The ENG1, ENG2, FWD, COMB, or AFT XMSN PRESS HI advisory will illuminate when the transmission oil pressure is above 90 psi. for the respective transmission
The Warnings Cautions and Advisory (WCA) page will alert the pilots when problems arise with the power train system. The caution and advisory summary page list the active advisories on the right side
a. There is a total of five transmission oil pressure hi advisories
The Warnings Cautions and Advisory (WCA) page will alert the pilots when problems arise with the power train system. The caution and advisory summary page list the active advisories on the right side
a. There is a total of five transmission oil pressure hi advisories
1) The oil pressure hi advisories cover the main oil pressures for the ENG1, ENG2, FWD, COMB, AFT transmissions
2) The ENG1, ENG2, FWD, COMB, or AFT XMSN PRESS HI advisory will illuminate when the transmission oil pressure is above 90 psi. for the respective transmission
All 5 MFD’s will indicate the two WARNINGS associated with the power train system. The warning will appear at the top of the MFD
All 5 MFD’s will indicate the two WARNINGS associated with the power train system. The warning will appear at the top of the MFD
(a) The ENG1 XMSN warning will indicate that the oil temperature at the #1 engine transmission is above 190 degrees Celsius
(b) The ENG2 XMSN warning will indicate that the oil temperature at the #2 engine transmission is above 190 degrees Celsius
All 5 MFD’s will indicate the two WARNINGS associated with the power train system. The warning will appear at the top of the MFD
All 5 MFD’s will indicate the two WARNINGS associated with the power train system. The warning will appear at the top of the MFD
(a) The ENG1 XMSN warning will indicate that the oil temperature at the #1 engine transmission is above 190 degrees Celsius
(b) The ENG2 XMSN warning will indicate that the oil temperature at the #2 engine transmission is above 190 degrees Celsius
Forward transmission indications will be shown in the blocks identified above
Combining transmission indications will be shown in the blocks identified above
Aft transmission indications will be shown in the blocks identified above
Aft vertical shaft indications will be shown in the blocks identified above
No. 1 engine transmission indications will be shown in the blocks identified above
No. 1 engine transmission indications will be shown in the blocks identified above
Engine CHIPS and Transmission CHIPS/DEBRIS annunciation colors:
(1) “CHIPS” annunciation is displayed in red
(2) “DEBRIS” annunciation is displayed in yellow
(3) CHIPS is higher priority than DEBRIS
Engine CHIPS and Transmission CHIPS/DEBRIS annunciation colors:
(1) “CHIPS” annunciation is displayed in red
(2) “DEBRIS” annunciation is displayed in yellow
(3) CHIPS is higher priority than DEBRIS
No.1 Engine Layout
No.1 Engine Layout
No.2 Engine Layout
No.2 Engine Layout
Maintenance Panel Power Train Indications
Maintenance Panel Power Train Indications
(1) Each chips, debris, main pressure low, auxiliary pressure low, pressure low or temperature high fault has an indicator for each transmission
(2) The configuration of the transmissions on the Maintenance Panel is how they are in the helicopter looking down from the top
Quill Shaft connects each engine’s output power to its respective engine transmission
Quill Shaft connects each engine’s output power to its respective engine transmission
Engine Drive Shaft Assembly
The engine drive shaft assembly consists of a single piece balanced shaft, an engine transmission adapter that is bolted to the transmission, and a combining transmission adapter that is a free floating adapter, and two sets of flexible coupling plates
Engine Drive Shaft Assembly
The engine drive shaft assembly consists of a single piece balanced shaft, an engine transmission adapter that is bolted to the transmission, and a combining transmission adapter that is a free floating adapter, and two sets of flexible coupling plates
Shaft Adapters
(1) The flex coupling plates are made from stainless steel and the engine adapter plates have a scalloped design for weight reduction
(2) When assembled, the grain of the steel plates is layered much like plywood for additional strength and the ability to flex
(3) Each adapter assembly is balanced as a unit
(4) One-piece engine drive shafts are balanced separately from their adapters
Synchronizing Shafts
(1) The synchronizing shafts consist of nine aluminum tubes joined by flexible couplings
(2) Forward Synchronizing Shafts
(a) The forward synchronizing shafts transmit torque from the combining transmission to the forward transmission
(b) The forward synchronizing shafts are located under the tunnel covers and the forward pylon aft fairing
(c) There are three large doors, each with two locking struts, and tethers which attach to the two smaller doors to hold them in the open position
(d) The large doors have indentations which provide additional clearance for the flexible couplings
Flexible Coupling/Bearing Cups
(1) Cups are located under the flexible couplings and bearing housings to provide clearance
(2) The cups have drains incorporated to allow water to drain overboard
Forward Synchronizing Shaft Overview
The forward synchronizing shafts consist of seven individual shafts numbered one through seven starting at the forward transmission
Forward Synchronizing Shaft Overview
The forward synchronizing shafts consist of seven individual shafts numbered one through seven starting at the forward transmission
Bearing Housing and Flexible Adapter
(1) A bearing housing and flexible coupling assembly is located on the aft end of the first six synchronizing shaft assemblies
(2) The bearing housing support is mounted to the airframe support structure utilizing elastomer shock mounts to reduce vibrations
(3) The mounts should be approximately centered in the support mounting structure
(4) The bearing housings are pressed onto the shaft assembly and have a grease fitting (Zerk fitting) that should be in the top position
(5) The flexible coupling assemblies are multiple layers of stainless steel plates layered for both strength and flexibility (like the engine drive shaft flexible couplings)
Forward Transmission Adapter
(1) The forward transmission adapter consists of a splined adapter and flexible coupling assembly, in which the plates are stacked like the engine drive shaft flexible couplings
(2) The adapter is a free floating assembly that slides into the forward transmission, allowing (longitudinal) forward and aft movement
Combining Transmission Forward Adapter
The forward adapter on the front of the combining transmission is a splined adapter that is secured to the forward output shaft of the combining transmission by a retainer and lockring
Aft Synchronizing Shafts
(1) The aft synchronizing shafts transmit the torque from the combining transmission to the aft transmission
(2) Located in the aft cabin area, they consist of two individual shafts numbered eight and nine starting at the back of the combining transmission
(3) Shaft number eight has a flexible adapter on the aft end
(4) Shaft number nine does not have a flexible adapter, and is used to phase the aircraft rotors
Aft Synchronizing Shafts
(1) The aft synchronizing shafts transmit the torque from the combining transmission to the aft transmission
(2) Located in the aft cabin area, they consist of two individual shafts numbered eight and nine starting at the back of the combining transmission
(3) Shaft number eight has a flexible adapter on the aft end
(4) Shaft number nine does not have a flexible adapter, and is used to phase the aircraft rotors
Bearing Housing and Plate Assembly
(1) The No. 8 drive shaft bearing housing and adapter assembly is located on the aft end of the shaft, which is visible using the access panel in the aft cabin overhead at station 507
(2) The bearing housing support is mounted to the airframe support structure
(3) The bearing housing is pressed onto the shaft assembly and has a grease fitting (Zerk fitting) that should be in the bottom position
(4) The flexible couplings are multiple layers of stainless steel plates for both strength and flexibility (like the engine drive shaft flexible adapters)
Aft Transmission Adapter
(1) The aft transmission adapter consists of an adapter and flexible coupling assembly (like the forward synchronizing shaft adapter)
(2) The aft transmission adapter is also a free floating splined adapter assembly that slides into the aft transmission, allowing (longitudinal) forward and aft movement
Aft Transmission Adapter
(1) The aft transmission adapter consists of an adapter and flexible coupling assembly (like the forward synchronizing shaft adapter)
(2) The aft transmission adapter is also a free floating splined adapter assembly that slides into the aft transmission, allowing (longitudinal) forward and aft movement
Aft Combining Transmission Adapter
The aft adapter on the rear of the combining transmission is a splined adapter that is secured to the aft output shaft of the combining transmission by a retainer and lockring
Aft Vertical Shaft
(1) Located inside the aft pylon in the top of the aft transmission, the aft vertical shaft transmits power to the aft rotor system
(2) The aft vertical shaft assembly extends from the top of the aft transmission to the aft rotor head
(3) The base of the shaft is splined to match the splines in the aft transmission, but does not have a master spline
Aft Vertical Shaft
(1) Located inside the aft pylon in the top of the aft transmission, the aft vertical shaft transmits power to the aft rotor system
(2) The aft vertical shaft assembly extends from the top of the aft transmission to the aft rotor head
(3) The base of the shaft is splined to match the splines in the aft transmission, but does not have a master spline
The upper section of the shaft is splined to match the splines of the aft rotor head and does have a master spline
The upper section of the shaft is splined to match the splines of the aft rotor head and does have a master spline
(5) A thrust bearing and housing assembly is bolted to the aft pylon structure and is used to support the shaft
(6) The support housing carries the entire load of the aft rotor system, and contains a single large ball-bearing assembly. Exceeding VNE with the LCT retracted places excessive stress on the thrust bearing
(7) The bearing is inside the housing assembly and receives oil from the aft transmission main oil system
(8) An oil inlet filter is mounted externally on the housing
(9) It filters the oil prior to entering the bearing housing assembly
(10) A chip detector located on the bottom of the housing assembly, provides an indication of metal particles in the oil
(11) The inner probe and the outer housing are separated by a magnet which attracts the metal particles
(12) The inner probe is the positive terminal, and the outer housing is the ground
(5) A thrust bearing and housing assembly is bolted to the aft pylon structure and is used to support the shaft
(6) The support housing carries the entire load of the aft rotor system, and contains a single large ball-bearing assembly. Exceeding VNE with the LCT retracted places excessive stress on the thrust bearing
(7) The bearing is inside the housing assembly and receives oil from the aft transmission main oil system
(8) An oil inlet filter is mounted externally on the housing
(13) Protected by the fuzz burn off module, located on the right side of the ramp area, just below the maintenance panel
(14) The fuzz burner system can burn off particles up to 0.002 of an inch in size
(15) The response time of the fuzz burn-off circuit is more rapid than that of the helicopter warning system; thus a successful burn off will be accomplished before any cautions illuminates
(16) If unable to burn off the fuzz, the chip will activate the AFT SHAFT XMSN CHIPS on the WCA summary page, and a AFT SHAFT XMSN CHIPS caution message on the MFD will illuminate
(17) At the same time, the corresponding CHIPS indicator on the MAINTENANCE PANEL will illuminate, thus identifying the transmission
(18) An oil pressure switch is located on the top of the housing assembly
(19) Low oil pressure at the aft rotor shaft is identified by the activation of the AFT SHAFT PRESS LO caution on WCA summary page and caution field on the MFD and the illumination of the AFT SHAFT “PRESS LO” light on the MAINTENANCE PANEL
Phasing the Rotor System
(1) Phasing of the rotor system is required to maintain the proper alignment of the forward and aft blades
(2) The blades are “color” phased, which means when the aft rotor, red blade is directly forward over the tunnel covers, the forward rotor red blade is forward over the nose
(3) Phasing of the rotor system is required whenever the synchronizing shafting is disconnected or one of the three main transmissions, aft vertical shaft, or a synchronizing shaft is removed
(4) The No. 9 synchronizing shaft is removed to facilitate the phasing
Phasing the Rotor System
(1) Phasing of the rotor system is required to maintain the proper alignment of the forward and aft blades
(2) The blades are “color” phased, which means when the aft rotor, red blade is directly forward over the tunnel covers, the forward rotor red blade is forward over the nose
(3) Phasing of the rotor system is required whenever the synchronizing shafting is disconnected or one of the three main transmissions, aft vertical shaft, or a synchronizing shaft is removed
(4) The No. 9 synchronizing shaft is removed to facilitate the phasing
(5) After both forward and aft rotary-wing heads are rotated and positioned so the same color blade on each head is forward
(6) The upper mounting lugs of the swiveling actuators on the left side of the forward head and the right side of the aft head are aligned with the pitch link mounting lugs and checked for alignment using a phasing block
(5) After both forward and aft rotary-wing heads are rotated and positioned so the same color blade on each head is forward
(6) The upper mounting lugs of the swiveling actuators on the left side of the forward head and the right side of the aft head are aligned with the pitch link mounting lugs and checked for alignment using a phasing block
Engine Transmission Characteristics
Engine Transmission Characteristics
(1) The engine transmissions turn the direction of engine torque 90° to direct it towards the combining transmission
(2) The engine transmissions are attached to the forward end of each engine
(3) The two engine transmissions are identical and can be used in either position, after making only minor mechanical conversions
(4) The left and right engine transmission lubrication systems are independent of each other
(5) Power from the engine is transferred to the transmission by way of the quill shaft
Engine Transmission Characteristics
Engine Transmission Characteristics
(1) The engine transmissions turn the direction of engine torque 90° to direct it towards the combining transmission
(2) The engine transmissions are attached to the forward end of each engine
(3) The two engine transmissions are identical and can be used in either position, after making only minor mechanical conversions
(4) The left and right engine transmission lubrication systems are independent of each other
(5) Power from the engine is transferred to the transmission by way of the quill shaft
Sprag Clutch
(1) An overrunning sprag clutch is installed in each engine transmission
(2) The outer race is driven by the engine, and the inner race drives the drive shaft to the combining transmission
(3) The clutch provides a positive drive connection to transmit power and permits freewheeling of both rotors when in an actual autorotation or during a simulated power failure
(4) Because of the freewheeling feature, no drag from the engine will be placed on the rotors if an engine (or engines) fails
Sprag Clutch Operation
(a) As the engine begins to apply power to the transmission output shaft the sprags are forced into an upright position, which locks the outer race and inner race together, driving the output shaft
(b) While the engines are operating normally, the sprag clutch continues to lock the inner and outer races
(c) In the case of an autorotation the output shaft (inner race) is allowed to break free from the outer race
Sprag Clutch Operation
(d) In the Emergency case, the outer race that is being driven by the engine does not grip the sprags and does not lock them onto the inner race
(e) The concern here is at some time during the operation of the engine the outer race will grip the sprags and immediately lock the outer race to the inner race, inducing a significant amount of torque being applied to both the transmission and the engine drive shaft, resulting in an engine drive shaft twisting in half or engine transmission damage
Oil System
Oil System
NOTE: We will be talking about a single engine transmission oil system, but will include information on the component locations for both the left and right engine transmission oil systems as necessary
(1) The oil type that is used must be stenciled on the transmission
(2) The type of oil used in the combining transmission and engine transmissions must be the same
NOTE: To prevent over filling the engine/combining transmission, check oil level within 30 minutes of shutdown. If the transmissions have been shut down for more than 30 minutes, operate the rotors for a minimum of 5 minutes to verify oil level before servicing
