ATR systems - Powerplant part 3 - Propeller

[Music] hi my name is magna noodle i am captain and instructor on atr 42 and 72 aircraft this video is about the power plant eastern asia aircraft the pratt whitney canada pw100 series this is a comprehensive subject therefore i have divided the video into four parts part one gives a general description of the engine part two is about the engine's cast turbine and if you haven't seen them i recommend you to watch them before you start on this video this is part three and it's about the propeller and part four is about the operating procedures this video is intended to give an oversight of the engine and i might have made mistakes and if i did please inform me and i will make a notification below here for a fully detailed description of the variant you're flying please read the fcom the flight crew operating manual dsc chapter 70 but stay put because i have added some information you won't find in the manuals as i explained in the previous videos the gas turbine drives the power turbine which drives the propeller via the reduction gearbox rgb the reduction gearbox has two stages the first stage has helical gears which gives a larger contact area enabling the gear to transmit larger forces the second stage is a spur gear which includes two small pinion gears and a large build gear the gear ratio is 15.4 on engine number two there's a propeller brake attached to the left hand pinion gear the reduction gearbox drives the ac wired frequency generator and high pressure oil pump and an overspeed governor attached to the gearbox there's a fuel called oil cooler and an electric auxiliary oil pump the primary function is to feather the propeller in flight and finally we have the propeller pitch actuator which is controlled by depending on engine versus the propeller control unit pcu or the propeller valve module pvm the lubrication system of the gas turbine is described in part 2 of this video the lubrication system in the reduction gearbox is simpler from the vehicle oil cooler the oil enters a small tank inside the gearbox housing it has many names auxiliary tank which i will use rgb oil tank and internal oil cavity the total capacity including unusable oil is 3.68 liters oil from the auxiliary tank is used to lubricate the reduction gearbox before the oil is collected in a sump which has a magnetic ship detector from the sump the oil passes a filter before it's returned to the main oil tank the reduction gearbox drives a high pressure oil pump which receives oil from the auxiliary oil tank only 0.32 liters of the oil in the tank is available for a high pressure pump but the supply of oil is continuous when the gas turbine is running the high pressure oil pump delivers oil at 1000 psi to the pcu or the pvm and to the overspeed governor the overspeed governor is attached to the high pressure oil pump casing and acts as a backup in case the normal propeller control fails like the high pressure pump the rsp governor sends oil to the pcu or the pvm inside the rsv governor there's a flywheel which rotates with the reduction gearbox the flywheel acts on a valve which drains oil to the surf when the rotation speed reaches a specified limitation here is a video showing how a governor in a steam engine works when the engine is running the weights are pulled out by the centrifugal force and this controls a valve that regulates the amount of steam that is used to drive the engine strictly speaking centrifugal force doesn't exist but is the opposite vector of an inwards acceleration caused by the rotational movement that is perceived as a force a second electrically driven oil pump is used to complement the high pressure pump the pump is called the auxiliary pump or the fending pump most of the oil in the auxiliary tank 3.22 liters is exclusively available for auxiliary pump this quantity is sufficient to feather a propeller when the gas turbine has stopped the auxiliary performance and the following conditions are met one in flight when the conditioner is moved to federal position or during 80 pcs sequence if you wonder about what atp says is please look at part one to this video two on ground during dynamic atpcs test or when the fire handle is pulled when the conditionary is set to fuel shutter position and was in feather position for less than 30 seconds before this happens when you have to abort and take off and evacuate in a hurry the auxiliary pump runs automatically for 30 seconds afterwards it needs 10 minutes to cool down early atl variants have a propeller control unit pcu with manual propeller control and 4 bladed propellers in blade governing mode the conditioner is set between max rpm which is 100 np and minimum rpm which is 77 np the pcu has the following components one speed sensitive governor which is controlled by the condition lever the governor meters oil from the high pressure pump to the server piston two the servo piston which is connected to the transfer tube the piste moves back and forth with the oil pressure from the speed sensitive governor a ball screw causes the transfer tube to rotate when it's moving for and aft the transfer tube receives oil directly from the high pressure pump three the least selector which is a valve that opens for the hydraulic line with the least pressure this is part of the propeller overspeed protection for the beta valve which is controlled by the probe lever when it's behind flight idle it allows for the power levers to control propeller pitch 5 the reverse valve which is controlled by the probe lever when it's behind flight idle when activated the reverse wire closes the line from the list selector and opens a line from the high pressure pump this gives the beta valve oil supply at optimum pressure 6. the feather valve which opens when the conditioner is set to feather position 7. the feather solenoid which opens during 80 pcs sequence and the fire handle is pulled 8 low pitch protection and indicating lower pitch indication is controlled by a switch that is energized when the engine is in fuel governing mode the transfer tube delivers oil from the server piston to the pitch change actuator in the propeller hub the transfer tube is also called beta tube as the propeller blade pitch angle is often referred to as beta a low blade angle is called fine pitch and a high blade angle is called core speech the pitch change actuator consists of the following components one a servo piston also called the york piston it can move back and forth two a shank which is attached offset to the base of each propeller blade it is inserted in a slot in the servo piston and when the server piece moves back and forth the shank will cause the propeller blade to rotate along its axis 3 pitch increased chamber when oil is directed into this chamber the therapist moves off causing propeller pitch to increase towards head position four a pitch decreased chamber when oil is directed into this chamber the therapist moves forward causing propeller pitch to decrease towards reverse position five a pitch change metering valve depending on the forward or off position on the transfer tube the p-change metering valve distributes high pressure oil into one of the chambers the oil in the other chamber is released and used to lubricate the propeller hub before it's drained to the sump 6. a pitch lock screw it rotates with the transfer tube and secures the propeller blades in the current position in case of a total loss of oil pressure this is how the pcu works in blade governing mode the high pressure oil pump says oil with 1000 psi pressure to the speed sensitive governor the condition never controls the tension of a spring in the governor which meters the oil pressure to the servo piston thus regulating np the oil is sent to the server piston via the list selector and the reverse valve which don't affect the oil pressure when the conditioner is set to max rpm the np will be one hundred percent and set to the right pan you get eighty six percent np and when set to minimum rpm you get seventy seven percent the propeller tends to turn faster than the desired np the speed sensitive governor will dump some oil to the sump reducing the oil pressure to the servo piston this causes the servo piston to direct more oil to the pitch increase chamber this will increase the load on the propeller and reduce np the opposite will happen when the propeller tends to turn slower than the desired np in fuel governing mode the ecu or the eec are just fuel flow to maintain seventy point eight percent np and the proper level acts on the reverse valve and the beta valve the reverse well directs high pressure oil to the beta valve which meters oil to the servo piston moving the probability forward will reduce the oil pressure to the server piston resulting in increased pitch and more forward trust moving the probability rearward will increase the oil pressure to the server piston resulting in reduced pitch and reverse thrust in fuel governing mode there's a low pitched light indication if the orisp governor registers more than 103.5 percent np the rsp governor will open the drain valve this causes the valve in the least selector to switch side this causes propeller pitch to increase and slow down the propeller propeller feathering is achieved by moving the conditioner to feather which opens the feather valve and by 80 pcs sequence after an ancient failure or by pulling the fire handle which opens the fatty solenoid i don't have information about how the low pitch protection works but i assume that it opens when the servo piston goes beyond the limitation for flight this will reduce the oil pressure in the transfer tube and reduce the movement of the piston in the p-change actuator the syncrophaser is attached to engine number 2 speed sensitive governor and adjust engine number 2 and p2 match engine number 1 and p and maintain the optimum phase between the propellers in order to minimize the noise the syncrovisor is inhibited when the power management is set to take off and is otherwise available on nps over 70 percent maximum authority of the syncoprizer is plus minus 2.5 np late atr variants are propeller electronic control peg and six bladed propellers which have the benefit of producing less noise this is actually by sweeping back the propeller tips which reduces the local mach number and by having more propeller blades which reduces the aerodynamic load on each blade in blade governing mode the condition level is normally set to auto each engine has a propeller interface unit piu which is an electronic box located in the electronic rack behind the cockpit it has the following functions one when the condition is set to auto the piu monitors the position of the power management selector this determines whether np shall be 82 or 100 the piu sends the signal to the pick two processing pack fault signals three inhibit propeller anti-icing when np is 63 or less the pack is installed on top of the reduction gearbox and has two channels the channels are self-tested for three seconds when the conditioner is moved from feather to auto a failure to one center with trigger and embedding channel light and the other channels automatically takes over a failure to both channels will result in a pec fault alert the propeller valve module pvm has the following components one the electro hydraulic valve ehv which is powered and controlled by the peck it meters oil to the p-change actuator and enables normal feathering of the propeller two the protection valve which is part of the np speed protection low pitch protection and backup for feathering 3. the feather solenoid which works with the protection valve 4 the rotary variable differential transducer rvdt which transmits the position of the power lever to the peg 5 a secondary low pitch stop detection solenoid i don't have any information about this one but i assume it's a kind of backup if you know the function of this device please let us know in the comments below depec receives the following information one from the piu when the conditionary is set to auto the position of the program management selector two from the condition lever when it's set to 100 override or feather the position of the condition lever three from the eec air speed and altitude four from the electro hydraulic valve the pitch of the propeller blades five from the rvdt the position of the probe lever based on this information the peg computes the p changes required to maintain the required np and send command signals to the electrohydraulic valve the two hydraulic lines enters the transfer tube which leads to the pitch change actuator in the propeller hub i have cheated a little here because i'm using the same drawing as for the engine with the pcu the main differences are there is no pitch lock screw there are two hydraulic lines instead of one in the transfer tube and i attach to the pitch change actuator and they don't rotate this is how the pvm works the high pressure oil pump says only 1000 psi pressure to the electro hydraulic valve which is powered and controlled by the peck based on signals from the peck the electro hydraulic valve meters all in two hydraulic lines the first line decreases propeller pitch or making it finer i mark this line with pink color the other line increases propeller pitch or making it coarser i have marked this line with green color excessive oil is strained to the sump in blade governing mode the peg calculates the changes in propeller pitch required to maintain the desired np and sends commands to the electro-hydraulic valve and the power management select is set to takeoff or mct and p is hundred percent and when the power management select is set to climb or cruise and p is 82 percent when power is increased or when the speed of the airplane increases the propeller tends to rotate faster the peck will then command electro hydraulic valve to meet the more oil into the hydraulic line that causes the propeller pitch to increase and vice versa in fuel governing mode the eec adjusts fuel flow to maintain 70.8 np and the probability controls propeller pitch by regulating oil from the holy speed governor into the pitch change actuator this figure is simplified and doesn't show the mechanism moving the probability forward will increase the pressure in the hydraulic line that increases propeller pitch moving the power level backward will increase the pressure in the hydraulic line that reduces propeller pitch towards reverse in fuel governing mode there is a low pitch light indication when the pack is inoperative the electro hydraulic valve is no longer powered in this case the hydraulic line commanding fine pitch is left open this causes np to increase this is when the osb governor and the protection valve come into play the protection value is located downstream of the electro hydraulic valve the protection valve consists of a moveable piston with several valves during normal operation the piston is held in position by oil pressure from the overspeed governor and the oil in the two hydraulic lines from the electro hydraulic valve to pass through the protection valve without interruption this is called unprotected mode when np reaches 102.5 percent the rsp governor starts to dump oil into the drain line this results in a reduction of the oil pressure to the protection valve this causes the piston to move gradually restricting the flow in the two lines from the electrohydraulic valve when the pressure from the osp governor is reduced to 50 percent the piston has moved to its full stop and the supply from the electro hydraulic valve is blocked the protection will be now direct all into the hydraulic line that increases propeller pitch this causes np to decrease and the rsp corner slows down opening up for supply from the electro hydraulic valve again and the np stabilizes at 102.5 percent this is called protected mode propeller feathering is achieved by moving the conditioner to feather by 80 psi sequence after an engine failure or by pulling the fire handle the 80 pc sequence is described in part one of this video there are two independent feathering systems the peck and the electro hydraulic valve provide the first head system the electro hydraulic valve meters all into the hydraulic line to increase pitch the second feather system consists of the feather solenoid which is open for 30 seconds and acts on the protection valve when the feather solenoid opens the oil pressure from the rsb governor is reduced and this causes the protection valve to go into protected mode and direct oil from the high pressure pump into the hydraulic line that increases propeller pitch when the airplane is in flight the auxiliary pump will run for 30 seconds and assist feathering of the propeller on ground the auxiliary pump will run during atp says dynamic test or when the fire handle is activated when the conditioner is infused off position and was in federal position for less than 30 seconds before the transfer tube moves for and after the p-change actuator when the propeller pitch angle moves towards low pitch the activator moves forward at a position corresponding to the lowest blade pitch angle allowed in flight which is 12.8 degrees the hydraulic line from the rsp governor is connected to the drain this causes the protection valve to going into protected mode and commands propeller pitch to increase the pack provides fully automatic synchro facing between the propellers it maintains an optimum phase between the propellers which minimize the noise this video shows how well the propellers are synchronized a take of the propeller speed is 1200 rpm and when the video camera has a shutter speed that matches this it appears that the propellers have stopped and this concludes the presentation of the propeller you may now proceed to part 4 which is about the procedures please support my channel by clicking like subscribe and share with your friends thank you for watching have a wonderful day and happy learning you

Channel: Fly with Magnar

Views: 31,929

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Id: j6W8esX0Z0w

Length: 21min 51sec (1311 seconds)

Published: Fri Feb 26 2021