ATR systems - Powerplant part 3 - Propeller
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- Опубліковано 24 лют 2021
- This is the third video in a series of four videos about the powerplant used by ATR aircraft. It gives a description of the intricate propeller control.
This video is not meant to give a fully detailed description of the system, but to give you an idea about who it works. Despite my effort to be as exact as possible, I might have made mistakes. If you find errors, please let me know, and I will add the corrections here:
1) The drawings show the turbine blades installed in the wrong direction. When viewed from behind, the HP turbine and the power turbine are rotating clockwise, and the LP turbine is rotating counter-clockwise. Here is a video from the engine manufacturer: • PW127XT engine series:...
2) The function of the Secondary Low Pitch Stop Retraction Solenoid is to block the return line from the metering window of the transfer tube. Thus allowing a lower pitch angle (less than 13 degrees) till reverse on the ground. It is operated by a microswitch in the power lever and allows for low pitch when the power lever is behind flight idle.
Links and attributions:
Engine part 1 - General: • ATR systems - Powerpla...
Engine part 2 - Gas turbine: • ATR systems - Powerpla...
Engine part 4 - Procedures: • ATR systems - Powerpla...
Governor: • Model Flyball Governor...
Take-off with “stopped” propeller: • Airplane takes off wit...
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EXCELLENT REVIEW! Thanks Cpt Magnar!
Tip top as always, you are helping out the whole community of ATR’s pilots.
Greetings from ALGERIA.
Thanks! 👍
The power lever energizes the secondary low pitch stop retract solenoid by microswitch 3KX (4KX) when PLA is below FI. When powered (closed), the solenoid blocks the flow of overspeed governor pressure (Posg) to drain. This lets the blade pitch to go below the minimum in-flight value for ground operation.
Thanks for clarifying this!
Excellent video Captain Nordal. I've been watching a few ATR training video from "Fly with Magnar" and I have to say they are the best ATR systems video I've seen. They are very comprehensive, and since there are not much flying for many of us during this down period, there is no better time to be revising on my ATR knowledge from your videos. Keep it up, I'll be watching the rest of your videos to make myself a better ATR pilot. Thanks Captain.
Excellent
Thank you Captain Nordal for your effort,time and dedication.Happy landings.
That's a lotta moving parts and fluid, along with a whole lot of electrical "thinking" going on..Whoooo, great job Dad. - Surry Virginia.
I think from now on, it's Professor Captain Nordal. 🧑🎓
Excellent presentation sir, keep doing great work
You sir are a genius. Thank you for the videos.
Excellent vedio to provide knowledge
the secondary low pitch retraction solenoid is activated by the PL when it reaches at or below 31 deg of PLA. FI at 37 deg, so the low pitch solenoid will get activated slightly below the FI position.
when activated it opens a pressure port that increase the low pitch pressure and there by takes the propeller pitch to ground configuration (beta at which the propeller produces less lift so the A/C remains static or produces minimum lift for taxing when PL above GI) this ground configuration includes reverse as well ..
if PEC fails then the solenoid cannot be activated as a result low pitch indication cannot come on though PLA
Thank your for your information. It is highly appreciated.
@@FlywithMagnar welcome sir can I get your contact .. because I wish to be in touch with you
magnar.nordal@gmail.com
@@FlywithMagnar thank you sir ....will contact you soon
Dear Capt, you are perfect as usual ,kindly provide us with a video regarding ATR avionics
Thank you. I have made an introduction to the avionics. The rest will come bit by bit.
It's really a very informative content, thankyou so much for sharing all your knowledge with us
Thank you
Dear Captain Nordal,
Congratulations for your magnificent ATR Channel - Lots & Lots of work on them.
As an A&P Mechanic & Instructor, I watch your modules with great interest since I do not have physical access to this aircraft and learn from them.
I would like to have some clarification from your end as it relates to the ATR Propeller Synchronization System since I do not have access to ATR’s FCOM Manuals.
Although technology is evolving with assistance from EEC, PEC, FADEC, etc., I lecture my A&P students that the Pilots do not normally engage Prop. Synchronization during the Take-off, Climb, Approach & Landing periods to minimize any drop in RPM’s in case of issues with Engine # 1 and, I think the FAA has some words on this as well.
In this Video @ 11:43 you mention that Prop. Synchr. is inhibited when the “PWR MGT” Knob is in “TO” position but otherwise available when NP is above 70% ( I figure any other positions on the “PWR MGT” above > 70% ) but at the end of the video @ 20:47 you mention that we can see Propellers Synchronized during take off. Is this just a Visual appreciation associated with the Video Frames ?
Please clarify and thank you again for your Magnificent effort 100+% .
Sincerely,
Roberto V. Herreria, BSME, A&P
Dear Roberto. Thank you for your feedback.
Different ATR variants have different engine variants. Engines without PEC have a pushbutton for the synchronizer. It is always engaged, unless specified by the checklists, for example after shutting down an engine.
Engines with PEC do not have a pushbutton for the synchronizer, as it is integrated in the PEC. Therefore, with the PECs operative, the propellers are always synchronized, including take-off.
And I will be waiting for next topic about flight control system, Namaste🙏 from india
The flight control system is on my list. Please be patient.
Excellent 👏👏👏
also on ground the activation of electrical feather pump through CL is not available / inhibited since mostly it is a normal situation rather than a emergency situation but atpcs will activate it on ground
Great work Captain, but where can we find a copy of the FCOM?
Thanx
The function of the secondary low pitch stop retract solenoid is to block return line from metering window of the transfer tube. Thus allowing lower pitch angle (
Thank you for this information. Just one question: How is the solenoid controlled? By power lever position, WOW or other means?
@@FlywithMagnar It is controlled by power lever microswitch when PLA below Flight Idle. Due to AMM dedicated switches are 3KX and 4KX.
Thanks a lot. When I made this video, I used a drawing where it appears that the solenoid is open during flight. But based on the information you provided, this might be wrong?
@@FlywithMagnar It is opened during flight and draws excessive oil from transfer tube fine pitch line to prevent low pitch
I also wish to discuss about the low pitch protection
Great video! I have realized there seems to be some sort of shielding on the fuselage right at the side of the left engine propeller. Do you know what this is for? I wonder if it is to protect from uncontained blade failure? Thank you, Captain Nordal!
Hi, the shielding on the fuselage is made of Kevlar and protects the fuselage from dents when ice is shed from the propeller blades. A blade failure cannot be contained, as the energy level is too high. However, propeller blades just don't break off. There has been an accident with a Dash-8 where a part of a propeller blade shed off after hitting the ground (or another solid object) and penetrated the fuselage.
@@FlywithMagnar Thank you so much for the informative reply. It was very helpful!!
Hi Capt. I am very much interested to learn about Atr 72-600 before my type rating. But no matter what, Im not able to get grab of the FCOM. A request if you can provide me the study material for the better good. I hope you will help me to gain knowledge. Regards
What is the maximum and the minimum pitch value of the propeller blade, approximately?
Hello Magnar, great videos!
I flew ATR long time ago and had a few questions.
Have you ever tried to unfeather running engine in actual flight? I remember in 72-212 it took about 20 seconds from FTR to AUTO on the ground before taxi. But do you think it might take longer in the air? Will there be any response If I'd move power lever on running engine with feathered prop in the air?
I know investigation will find out but still I am very qurious if Yeti pilots had any chance if they would unfeather props at this low altitude in high terrain ( provided that they actually confused flap and CL which is a strange and exotic case)
Thanks!
Hello. My experience from the simulator is that it takes slightly less time to unfeather the propeller in flight. So yes, if they had discovered the error in time, they could have saved the day. When the engine is running with the propeller feathered, the NH rarely changes when the power lever is moved.
sir please include, the electrical feather pump is activated by fire handle as well in flight....any emergency action corresponding to isolation of engin in flight or on ground it will be activated
so when electric pump fails ..we cant feathet the engine in emergencies right?i think hp pump runs while gas turbine is running only
Sir,
You have such immense knowledge about the engines, as if you are a mechanic. Great.
My curiosity drives me to ask you a question. Does a pilot need to know so much ? Or was it your interest to learn as much ?
But I do appreciate your knowledge.
No, that is not necessary. The pilot only needs to know how to operate the systems.
good day captain, thank you for your skill sharing and your effort.
I wonder here are a lot of procedures and studies for ATR600 in UA-cam this time, but I is really hard to get an information about ATR 500.
I hope you up load about ATR500 procedure please.
thank you and safe flight
Thank you for your feedback. When I make videos about the systems, I incorporate all ATR variants, from the 42-300 to the 72-600. But when it comes to the procedures, it's a bit harder, as I only started to film seriously in the cockpit a few months ago, when I was flying the 600. When possible, I will continue to compare EFIS variants with glass cockpit variants when I make videos about the procedures. Later today, I will publish a video about procedures related to the powerplant.
@@FlywithMagnar Thank you very much of your consideration, I totally understand what you are saying . I learn from you a lot BTW sir. keep safe flight and up load good knowledge captain.
If you notice in the engine limitations section of the FCOM (72-500/600 variant), it is stated that " operation upto 106.3% torque is time unlimited when NP is below 94%". Could you please shed some light on this? Which scenario would this be possible in?
Engine power is NP multiplied with TQ. When NP is 100% and TQ is 100%, the engine produces 2,750 hp.
With 100% NP, the engine can run at 120% TQ (3,300 hp) for 20 seconds, and at 106.3% TQ (2.923 hp) for 10 minutes.
94% NP at 106.3% TQ equals 2,747 hp, and the engine manufacturer has determined that the engine can run with this power for an unlimited period of time.
When the power management is in CLB or CRZ, the propeller runs at 82% NP. If you for some reason moves the power lever to the ramp or to the wall, the torque will exceed 100%. Possible scenarios: Stall recovery, windshear, or go-around while the power management is in CLB or CRZ.
@@FlywithMagnar @Fly with Magnar Thank you for your response capt. My understanding here was that if the PWR MGT is left on CLB or CRZ, and we end up moving the PL beyond NOTCH over a specified period of time, the engine will end up with an over torque.
Couple of scenarios where the crew has done a mismanaged GA with PL in ramp position without the NP on 100 percent ( PWR MGT not on TO/MCT), has resulted in the system tagging an exceedance in the limitation of the engine torque. The TQ Probably went over 106 in these scenarios(not sure). Will look more into it.
Hello! Could you make a video about programming the fmc/mcdu of the atr 72/42 600?
If you mean the FMS, then yes. But it will take a little time before I get there.
@@FlywithMagnar Thank you, sorry for my spelling mistake
Question: In what condition you would prefer to use 100% NP on approach, on PEC equipped aircraft?
When I expect turbulence and/or windshear on short approach and landing. 100% NP gives better engine response.
@@FlywithMagnar thankyou for the answer.
Hello, Captain. What is the purpose of the EEC (and other components 15:01) sending data to the PEC if propeller speed (NP) is always at 82% or 100% depending on the PWR MGT selector in blade governing mode? I am a bit confused since the manual says the PEC computes propeller speed using these data.
Airspeed and air pressure changes will affect the rotation speed of the propeller. For a given pitch, higher airspeed reduces the angle of attack of the incoming air, increasing the rpm. The PEC uses this information to control the pitch of the blades to maintain constant rpm. For example, during takeoff the airspeed changes from 0 to over 100 knots. So the PEC compensates for those changes.
blancolirio sent me here
Welcome! I'm honored Juan recommened this channel.
Hi capt.
1) Why does MCT have no time limit, while TO has a 5 min limitation when MCT is actually generating more power at 90.9 vs 90.0 by the TO position, both being generated with a 100% np and PL in the notch position?
2) The new EGPWS procedure asks for pwr MGT in MCT instead of TO position, PL to the notch, then eventually advance PL to the ramp if necessary ( i think it will always be safer to use max power in a case of egpws, so better to use ramp straight away). My question is, is there any time limitation when using MCT with PL in ramp position?
Thanks.
Hi, my answers are for variants with PEC:
1) The life of an engine depends on wear and tear, especially in the hot parts of the engine. During take-off is the torque is set to 10% below RTO power just to reduce the wear of the engine. This happens at every take-off. MCT is an emergency setting and is rarely used at all, but the engine will not melt away. Therefore, it's safe to use when you really need the power.
2) PWR MGT is only set to TO for take-off and landing. It increases NP to 100%. But on approach, NP will only increase when you advance the power levers. The MCT position commands NP to 100% regardless of the position of the power levers. But if you already have set the PWR MGT to TO (for example during approach), then leave it there.
When the PWR MGT is either in TO or MCT position, and you move the power levers to the ramp, the result is the same: 100% torque (unless in hot and high conditions). This torque is used at every go-around.
Some companies are also using 100% torque at take-off from short runways. The side-effect is that the engine will need more frequent hot section overhauls, which are expensive.
There's no published time limitation for using MCT with PL at ramp position. But you should only use it when needed.
@@FlywithMagnar makes sense. Thank you for the detailed discussion capt.
Hi, it seems that Yeti YT-691:s props went to feather simultaniously. Any clues what could've caused this?
The report didn't say the propellers feathered simultaneously. Just that both were in feather. Neither does the report tell whether this was an observation from the crash site or data from the FDR. Therefore, it is impossible to know how this happened.
Hi Capt., why does a prop over limit happen? Thank you
Short answer: When something goes wrong with the propeller pitch control. There are many safeguards, but Murphy's law is still valid.
@@FlywithMagnar thank you captain
Sir i have 1 question. I don't know the answer, pleas hlp me
1. PEC fault, NP limited max 102.5% but tendency to more high. What the nect limited.?
If the PEC fails, the overspeed governor limits NP to 102.5%. If the overspeed governor fails as well, there's no further protection. What happens, is that NP continues to increase. This is called LO PITCH in flight. The pilots must shut down that engine as soon as possible.
When CL move to override .? PEC sgl chnel or PEC fault/off.?
When the checklist calls for it. Single channel doesn't affect the propeller control. Therefore, no action is required. A PEC fault means both channels have failed. In that case, NP increases to 102%, and the procedure is to safeguard it by setting the condition lever to 100% override.
@@FlywithMagnar thank you for the answer it really helped me, have a nice day
Dear Capt a friend of mine believes that if we set the CL to 100% override once CLB procedure is done it improves CLB performance, I’m sure it’s a wrong practice, but I don’t know how to discribe it to him, kindly please have a comment regarding why this is NOT a good procedure thanks
My arguments are: 1) Disregard of standard procedure laid down by the manufacturer. 2) Waste of money because the engine will burn more fuel and run at higher temperature, which in turn will reduce engine life. A hot section overhaul is very expensive. That's why we use reduced power at take-off. 3) Cabin noise.
if CL set to 100 / override at higher altitudes then the propeller speed increase that results in lower propeller pitch for a specific fuel flow. as we know the TAS increase as altitude increase and if TAS increase this results in low beta ( angle of attack). so higher TAS and less beta results in less lift produced by the propeller for a specific fuel flow.
now, as the beta decreases the TQ also decrease, so inorder to give a compensation to such situation EEC will burn more fuel to regain some TQ since top law is a function of TQ
so 100 overide is not to be used except sever icing conditions or propeller anti icing fails in icing conditions
during TO phase 100 / really helps because...engine operates at high power and since we are at low altitude and less TAS increased NP will process more air at low pitch like a fan (that is why low TQ during TO than climb and cruise) results in generating lift at low TQ to handle the TO load.
irrespective of all the above, 100 / np will only increase more drag and reduces lift when PWR MGT at CLB/ CRZ. also cabin noise is increased....so it gives no advantage instead it gives only disadvantages and reduces climb performance
Why does the engine sound change so dramatically when condition lever is moved from Feather to Auto after start? Does the condition change also increase the engine RPM in addition to changing the propeller pitch?
What you hear is the increase in NP (propeller RPM) from 15% to 71%.
@@FlywithMagnar Thanks for the reply, captain! 😊 Just to be sure: does the condition lever also increase the engine power or is Feather -> Auto changing only the pitch of propeller?
I believe power is also increased along with pitch change(from low pitch to a higher pitch).
This is because ordinarily, any increase in blade pitch(ONLY) often results in increased drag & consequently reduced rpm.
Capt, I am Capt Suresh from India flying ATR for IndiGo. I have a doubt regarding critical engine in ATR. I want to know, which engine is critical engine and why? If left engine is critical, then it has to have a positive angle of incidence during Take Off run or it has to be in a climb.
I request you to pls explain this in detail pls.
The left engine is critical because both propellers are turning clockwise when observed from behind. Please watch this video for further explanation: ua-cam.com/video/_lxA0NojuwY/v-deo.html
Capt, does this explanation stands when the ATR is on ground and accelerating for a T/O???
@suresh pakala, when the aircraft is on the ground, the propellers produce even torque. The critical engine is defined as the one whose failure would result in the most adverse effects on the aircraft's handling and performance in flight.
What could be the possible cause if only one blade is in unfeathered condition while all other blades are in feathered condition after engine shut down
I have never heard about that before. There must be a mechanical failure in the propeller hub.
@@FlywithMagnar Thankyou for the reply.
Take off distance & engine performance on wet and dry days.
Could anybody explain above in detail? I am unable to find proper explanation in internet. 🇮🇳
For a start, please watch this video: ua-cam.com/video/AIfwMy-rhig/v-deo.html
@@FlywithMagnar ok. Thanks