ATR electric systems - an introduction

This video is a short introduction to electrical systems in ATR aircraft. You may find this useful when you watch videos about the other systems, or when you watch my videos about accident investigations.
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[@iamra_n3189]

I'm working through systems CBT for my ATR 72-600 type rating right now...these videos are a brilliant supplement. And, sometimes more informative and almost always more entertaining! Great work, Magnar!

[@daoudimohammed5080]

I just found this video, and gues what a thumb up + subscribe. well, I would like to say thanks, as a first officer on ATR72-500, type-rated since one year now, I'm still learing about the systems especially electricity and Power plant, so I would I'm so keen to get more of your lessons regarding this little bird. thanks a lot

[@w4r10ckc92]

Hello captain! Great video, explained in a very precise and concise manner! Very handy before a quick mock up session!

[@shafeekmpk]

Very clearly and simply explained.. Thanks

[@k9tiagopinto]

Good day. Once again I was impressed with the quality and simplicity of the explanation . Thank you

[@enashfirnas]

Clean and simple explanation. Thank you Captain

[@shanon411]

Thank you so much for your videos captain. God bless you.

[@wilfredotoledo9518]

Outstanding videos! Very helpful for knowledge review. Thank you for taking the time to put it all together. I can’t wait to see more.

[@FlywithMagnar]

Glad it was helpful! I will make more videos in the future.

[@jappaji3744]

Bravo , your videos activate my brain cells with ACW & I start buzzing @ 400 Hz. Thank you very much.

[@hieraclesjunior4636]

I'm starting as a maintenance technician for a Brazilian airline that uses ATR, I love this aircraft. Your videos are really cool, I learn a lot. Thanks so much.

[@michaelaficovic5250]

Thank you very much for all your very good ATR lessons. Very good for the prep for SIM sessions.

[@FlywithMagnar]

Glad you like them!

[@tejn6173]

Dear capt , what a wonderful explanation,,,,,looking fwd to many such videos!!! I had the privilege of undergoing a simulator session in 2015 at Bangkok with you .

[@thomaschipeaux4926]

Hello Capt Magnar, thank you much for your great videos :)

[@mrbushpilot]

Great videos, Magnar

[@satriopiningit5227]

Thnks capt. ,have helped thank you very much .atr 72500/600 engineer from Indonesia

[@toyhej]

Really good basic introduction.

[@Bobivankendeng]

Thanks capt. Your explanation is very is to be understood by normal people. I hope my come true sooner, to be aircraft engineer

[@yams900]

Kämpe gott, tack Magnar !

[@aviationtalkandtutorials2456]

Very good work commander,

[@bayteg]

Very simple and good explanation.I will spread this channel to my friend that's fly atr.And I'll wait for next videos.👍

[@FlywithMagnar]

Thank you! New videos are in the making.

[@travelwithmahedul1363]

Great Explanations sir. Im an ATR Pilot too. Your presentations enlightened me and now im more clear about Electrical system of ATR. Regards and happy landings sir.

[@aviacaoesimulacao]

Amazing video! Thanks!

[@octaviogomes7838]

Great video... :) Thank you so much!!!

[@brunocostanzo9514]

Good and great job Captain Magnar..!! My name is Bruno, I´ve been flying ATR since 1995, and assisted many classes, refreshing courses, briefings and sim sessions, I like and enjoy all your videos. Congratulations..!!

[@FlywithMagnar]

Thanks Bruno!

[@GabrielCKundaQFIpsc]

Well done!

[@yacinekassa7515]

Thank you captain it’s great .

[@cedricandriantovo]

thank you so much captain for all those videos, it's really helpfull for me as a new F/O in this aircraft!! i hope we'll meet in one of ATR ATC center one day... regards from Madagascar ^_^

[@brunocostanzo9514]

🛩🙂 Very nice resume..!!

[@heaye]

WoW ! I understand ! Thank you !

[@geraldomiguel6787]

Love the videos. Still no experience in ATR aircraft. but your explanation helps me before i get my type rating. Thank you. i wish you have videos about airconditioning and pressuration :D

[@espaciodeaviacion8257]

He has in his channel

[@HimanshuSharma-tr4dj]

Please make some more videos on ATR 72 Systems. Learning made easy with Captain Nordal. Thumbs up !

[@FlywithMagnar]

Here we go again. This time is it ice & rain protection systems on all ATR variants. Enjoy! kzbin.info/www/bejne/iJSxiGN3rraKa8U

[@florentcapron]

Bravo!

[@nelsonaung4163]

Thanks you capt

[@arunkumar.r678]

Very good presentation, a lay man can understand. Please do avideo for flight controls.

[@FlywithMagnar]

Thank you for your feedback. The flight controls are on the list for future videos.

[@dt7843]

Electricity will save us from the climat crisis emergency change. Thank you ATR-42 !

[@alphabravo5266]

Ty sir!

[@nomak2278]

hi, firts of all thank you for the videos, can you do another video about engine i mean speaking about the diferent special parts i learn more watching your videos than reading fcom several times and if you can , another video speaking about problems associated with the diferent C/L thank you so much captain! happy landings

[@FlywithMagnar]

Thank you! Yes, I am working on a series of 4 videos about the engines.

[@nomak2278]

@@FlywithMagnar I can't wait!!!

[@lkjhcasual]

спасибо

[@Porsche_Sooyeon_Kang]

Thank you for the Video, Capt! I have questions about DC GEN 1+2 FAULT in QRH. When if no TRU arrow light, MAX IMC FLIGHT TIME : 30 min 1) Why IMC? Is there special reason? 2) I guess ‘30 min’ time limited due to batteries usage time. Is that correct?

[@FlywithMagnar]

On battery power, with the battery selector in OVRD, the main battery powers DC ESS BUS, DC STBY BUS and AC STBY BUS, while the emergency battery powers DC EMER BUS. After about 30 minutes, the main battery will be empty, and you are left with the DC EMER BUS, which powers COM 1, ATC 1, and the stand-by instruments. You have no navigation aids, but will be able to receive radar vectors. When you are about to commence the approach, you press the STBY BUS OVRD pushbutton, and the emergency battery will be connected to the DC STBY BUS and the AC STBY BUS. This activates the captain's EADI, VOR/ILS1, landing gear control, and flaps control, enabling you to fly an approach and land. (I'm assuming you are flying ATR 72-500.) The procedure with no TRU is found in MMEL 24-30-02P.

[@Porsche_Sooyeon_Kang]

@@FlywithMagnar Wow, I totally understood ! Thank you so much capt !!

[@shanon411]

@@FlywithMagnar thanks. 🙏

[@mkarthik123]

Great video Capt, had the pleasure of undergoing a sim session with you in Bangkok. Question: could you please clarify why INV 1 is a No go item?

[@FlywithMagnar]

In case of loss of both DC generators, only inverter #1 can supply AC STBY BUS. This bus is very important, especially when you have an EFIS cockpit.

[@littlewingpsc27]

That was a great overview of the electrical system. So other than the internal batteries (Main & Emergency), there is no other back up auxiliary power unit that can be started, that runs off of the planes jet fuel, that can be used as a battery charger or tied into the electrical system if the batteries become discharged, and you don't have a power cart at the airfield? How would a remote airstrip operation work then? You have to have a generator at the airfield? What voltage and current rating of the external power cart is required to allow a ATR 42/72 to be powered up if the batteries are too low?

[@FlywithMagnar]

First of all, we take precautions to ensure that we do not deplete the batteries when we are on the ground. When an airport does not have ground services, and we have short stop, we let engine 2 run with the propeller brake engaged, so-called "hotel mode". When we have a long stop, we shut down everything and start engine 2 in hotel mode before boarding. The batteries can be charged by external ground power (GPU). ATR aircraft requires 28 V DC ground power. It must deliver 300 Amp plus additional 1000 Amp during start where the voltage must not drop below 12 V.

[@littlewingpsc27]

@@FlywithMagnar Thanks for responding.

[@TheSiberier]

Hello! Thank you for your videos! It is amazing! One question: when we have to switch on and switch off the TRU according checklists?

[@FlywithMagnar]

You switch the TRU on before taxi and off after landing. I'm working on a video about the TRU right now.

[@derekmay33]

Thank you once again Magnar, I m constantly learning about this aircraft. Can I just ask you about the difference between a BTC and a BTR please? Does the BTC just allow 1 DC generator to supply both sides and the BTR allow 1 inverter to supply all AC bus bars? Is this correct? Do they do anything else? Thank you!

[@FlywithMagnar]

Yes, you are correct. The BTC allows for one DC generator, or external power, to power all DC electrical systems. It operates automatically, but it can be isolated manually. The BTR connects AC bus 1 and AC bus 2 in case of an inverter failure. There's no indication showing whether it's open or closed. But you now it's working when you have an inverter failure and all AC busses remain powered. However, when you isolate the BTC manually, you also isolate the BTR.

[@derekmay33]

@@FlywithMagnar that's great Magnar, I appreciate you taking the time to reply. Electrics can be a bit of a head scratcher at times but when when you break it down, it's about electrical supply and how it's backed up. Thanks so much again!

[@fauxflights77]

Thank you so much for the videos. I have a question, if you don't mind. In my flights in MSFS, I've noticed that the condition levers have to be in AUTO for some time before I can engage the TRU, usually when I am getting into my taxi, but that it won't be engage-able at any point before that. Do you know what the necessary condition is for it to be actionable? Is it related to the prop speed or is it a matter of ACW power generation hitting some threshold? I am curious more than anything and would like to understand what is happening under the hood for that to become available.

[@FlywithMagnar]

The TRU is powered by ACW BUS 2, which is powered when at least one ACW generator is online, which requires the associated NP to be more than 65%. You should not start taxi until both NP are stabilized at around 71%.

[@fauxflights77]

@@FlywithMagnar Thank you so much! My virtual passengers say thank you!

[@leejbarker32]

Is there anywhere I can get the FCOM for the 600 series?

[@KRZYMANIAK]

Funny you mentioned that about the TLU. We were just going over the QRH and a DC BUS 2 failure (72-500) and how to go about the lost equipment list. Should all items on the loss list be reviewed through the QRH or should we skim and find most relevant? With something as important as the TLU auto function lost it would seem it should be included in the main body of a DC BUS 2 lost checklist. Maybe on the 600 a page is queued up. How do you approach the lost equipment list?

[@FlywithMagnar]

Hi, first of all, abnormal and emergency checklists must not be modified without consent from the manufacturer, as they are part of the certification of the aircraft. I only have the 72-500 QRH from 2009, and the checklist for loss of DC BUS 2 is different from the checklist for the 72-600, which I am flying today. In the checklist for the 72-600, the TLU is included. I recommend to read every item in the lost equipment list. Some items might be irrelevant, but you will only know after reading the list. If required, enter a hold and sort it out. Some years ago, I had a DC BUS 2 fault, and since we were 70 NM from the airport, we had plenty of time to read through the list, and prepare for the approach. We even had time to look out and enjoy the scenery.

[@KRZYMANIAK]

@@FlywithMagnar "take your time" is always a good approach. Get a cup of coffee and work the problem assuming it's not an emergency. I was also curious how to interpret the lost equipment items for "BATT only" and "STBY BUS". For BAT only (ACW available) I assume this is lost equipment under a TRU operation with no HOT BAT BUSSES? And STBY BUS lost equipment is if somehow we lose those busses? Seems the only way to interpret it. Mange tak for hjælpen Magnar. .

[@sofianesaidi8084]

Great job One question pls? How and when we use Table of lost équipement List dc +ac stby bus ?

[@FlywithMagnar]

Loss of both DC STBY BUS and AC STBY BUS happens when both DG generators have failed + no TRU + the main battery is empty (STBY BUS UND/V light). You can read the lost equipment list when you have time, but it's more important to fly the airplane. You are left with the emergency battery, which powers the standby flight instruments, trims, VHF1 and transponder 1. About 10 minutes before landing, you press the STBY BUS pushbutton, which powers captain's EADI (EFIS cockpit; in a glass cockpit, you continue to use the IESI), NAV1, flaps control, and landing gear control. This enables you to fly an ILS and land.

[@sofianesaidi8084]

@@FlywithMagnar thanks a lot Captain

[@daoudimohammed5080]

Hi everybody, I was wondering if there is a forum for ATR's pilots or technicians? I mean to go deeper into the systems and learn more about how to deal with faults on ground and in flight.

[@FlywithMagnar]

This channel is for pilots and everybody interested in aviation. If you watch my other videos, you will see they are about aerodynamics, licenses, Covid-19, accidents, and flying. I made this video specifically for an accident report I am preparing. In that incident, the electrical system played an important role.

[@daoudimohammed5080]

@@FlywithMagnar well I can't wait to see that accident report you're working on I wish you good luck! and as I said in a previous comment, I am an ATR 72-500 First officer, I've started my career one year ago, and I'm willing to go deeper in systems studying and understanding obviously to be able to deal with the faults and problems when flying this aircraft. looking forward to learn more and more from your knowledge. thanks a lot!

[@castleofaargh2093]

Question, the FCOM states that the Propeller AntiIce will not function below 63% NP. I’m pretty sure the ACW generators require 66% NP but I can’t seem to find it in the FCOM anywhere. Do you know what NP value the ACW generators come online?

[@FlywithMagnar]

If I remember correctly, the ACW generators require 65% NP to operate. Minimum propeller speed with engine running is 70.8% NP. One ACW generator can power both ACW buses and therefore all systems powered by ACW. In case of an engine failure, the associated propeller de-ice is not required. Therefore, propeller anti-ice is inhibited when NP is below 63%. This protects the propeller from heat damage.

[@tazpilot]

Good evening Capt. May I ask you where I can find the ATR 72-500 system failures, with the same method like you use in yours videos. I mean for example: if you have a DC Bus 1 fault which one bulb on and whom remaind off. I do not know if you understand what I mean, however great videos congratulations for your support.

[@FlywithMagnar]

Since you mentioned DC BUS 1 fault, I will explain how I will find information about that failure. The main indicator for a DC BUS 1 fault is the "DC BUS OFF" light on the main electrical panel. Since this bus powers several systems and other buses, there will be several other indications. When this failure happens in flight, you will use the procedure in QRH, where you also will find a list of affected systems. To get a full understanding, I use FCOM.PRO.NNO.ABN.24 which, in addition to the information in the QRH, describes the other alerts (DC GEN 1 FAULT, etc.), and FCOM.DSC.24 which describes the electrical system in detail. Then, I will check each one of the affected systems and find out whether they trigger an alert or just go dark. For example, when DC BUS 1 fails, the autopressure system fails. The indication is "AIR" on the cap, and a "FAULT" light in the MAN pushbutton on the panel. And so on.

[@tazpilot]

@@FlywithMagnar yes Capt. But I want to know where I can find this explanation like your videos, because I saw a lot video about system (btw your explanation is real one of the best that I saw), but not one about system failure. If I do not find it I want to do it myself but I do not know how to do it like your presentations in spanish however I have a youtube channels without voice with few procedure but like a told you I want to make system failure presentention o find it like yours.

[@FlywithMagnar]

@@tazpilot I don't know about others making videos about system failures. I present some of the failures in my videos. Regarding producing videos, I do by trial and error. I use VSDC Free Video Editor, which works well for me, but the initial learning curve was steep. Thankfully, there are many tutorials on YT. I take a lot of pictures and have FCOM for most of the variants. I also draw figures with PowerPoint and use PhotoShop.

[@nayyarjaffery1051]

Please make video in Flight Control. Thanks

[@FlywithMagnar]

Hi, it's on my to-do list. I will make a series of videos about the engine first.

[@ustio834]

Hello captain. I have a question, why do you need to turn off green hydraulic when DC gen 1 and 2 is lost?

[@FlywithMagnar]

The answer lies in the TRU. When both DC generators are lost, we select the TRU to conserve the batteries. The TRU is powered by ACW BUS 2. Early ATRs don't have TRU, and when it was introduced, the rest of the electrical systems were not changed. The ACW generators have limited capacity. To prevent overload of the bus, some load must be removed. The solution is to switch off the green hydraulic pump.

[@SouthlandFlyer]

@@FlywithMagnar To add to that, ATR expect that a DC GEN 1+2 failure occurs when one engine has already failed, and subsequently the remaining generator fails. This means that the whole ACW system is running off one generator. Turning off the green pump unloads this remaining generator.

[@derekmay33]

Hi Magnar, are the batteries not 28 volt? I did see reference to 24 volts in the FCOM too but I always thought that you would need 24 volt batteries to power a 28 volt DC system. By the way I'm not trying to catch you out. I was just wondering if there was a reason for this. Many thanks for your help and great video as always!

[@FlywithMagnar]

Batteries always have less voltage than generators. This prevents the batteries to discharge in case the generator voltage drops below normal. Furthermore, battery voltage varies. When freshly charged, the voltage is higher. When used for a while, the voltage is less. However, DC electrical equipment can work without a hitch down to 18 to 20 volts.

[@derekmay33]

@@FlywithMagnar thank you for explaining this Magnar, that is very interesting! I owe you lot of pints of Guinness if you ever find your self over here in Ireland!

[@FlywithMagnar]

Thank you. I used to go to Dublin some years back. Did some instruction at Simtech.

[@bucksraj]

Can you explain ADAPTED FLIGHT-IDLE

[@FlywithMagnar]

Yes. When selecting flight idle at high speed, the propellers produce high aerodynamic drag. This is helpful when it comes to reducing the speed for approach and landing. However, the disturbed slipstream behind the propeller affects the wing's ability to produce lift at a high angle of attack (AOA). Therefore, the EEC will automatically increase the fuel flow when the AOA is less than stall warning threshold minus 4°, reducing drag and ensuring that the propeller slipstream does not disturb the airflow over the wing. (FCOM.PRO.NOP.NSU.70.7)

[@pilotalex5677]

Hello Magnar, is TRU used in normal operation flights or just as a safety measure when needed ? Thank you

[@FlywithMagnar]

TRU was designed to allow for ETOPS operations. But after two incidents where all instruments were lost, we use the TRU for every flight as a precaution. ATR has tracked the error to a design fault in the battery switch. When the switch is replaced, we will not use the TRU any more.

[@pilotalex5677]

@FlywithMagnar It reminds me of Captain Sully (Hudson River water land) who chose to switch on the APU despite the fact it wasn't written on the checklist . Smart move gained with experience 👌

[@paulloveless4122]

I only have a recreational license but I love to study systems like this. I find 400hz to be a strange AC freq. Do other aircraft use this freq?

[@FlywithMagnar]

Yes, 400 Hz is common in aircraft.

[@KRZYMANIAK]

Hi Magnar, is there a theoretical discharge rate for the HOT MAIN and EMER BAT BUSES with the battery switch off? Because they are HOT, there must be some sort of depletion over time.

[@FlywithMagnar]

Hi. All batteries will detoriate over time, but we are talking about months. However, the main battery might be depleted if the GND HDLG bus C/B is not pulled, and the refuel panel door is open, or the cargo door is operated.

[@KRZYMANIAK]

@@FlywithMagnar thanks for reply. Just thinking the ATR batteries would drain quicker with a HOT bus connected to them compared to battery that didn't. Thanks again

[@kenster7368]

Question for you @flywithmagnar Aircraft on the ground with the engines running at max RPM and the ACW EXT PWR AVAIL/ON. What will happen when you select ACW BTC pb to ISOL? Im stuck on this

[@FlywithMagnar]

This is a perfect scenario to test when you are in the simulator! The more curious we are, the more we learn. - - - When ACW EXT PWR is ON, it is the GPU that supplies the ACW buses as EXT PWR has priority over the generators. When BTC is set to ISOL, the connection between EXT PWR and ACW BUS 1+2 is lost. But from then on, I'm not 100% sure. I am 99% sure that the ACW generators will start to supply their respective ACW BUS. - - - The ACW SVCE BUS is powered by ACW BUS 1 as long as ACW BUS 1 is powered. If ACW BUS 1 is lost (1% chance in this scenario), ACW SVCE BUS will be powered by EXT PWR.

[@kenster7368]

@@FlywithMagnar thank you! We are in the sim later today and shall try it

[@cruxader27]

I read in my FCOM that Emer/Main Bat Chg Fault is no longer allowed for reset procedure. I wonder whats the reason behind that?

[@FI2006007]

It is long time ago since my last flight on ATR but I remember at that time they were talking about of the reset of Bat Chg was not advisable since there might be a chance of a thermal runaway of the battery. I do not fully remember the details but it was something regarding that. I can not find my notes to give you a better explanation, sorry about that.

[@FlywithMagnar]

BAT CHG amber "FAULT" light illuminates when there's a thermal runaway or a charge contactor failure. From QRH, General information, section 3 Failure Consequences Analysis: "For the following systems the flight crew should strictly follow the abnormal procedure and RESET only when it is called by the abnormal procedure: - ECU / EEC. - PEC. - CAB PRESS MODE SEL. - BAT CHG (EMER & MAN)." The procedure for a single BAT CHG fault is to switch the affected BAT CHG PB OFF. Reset is not an option. However, the QRH is intended for use in flight. During engine start, we sometimes experience a BAT CHG fault message; it happens at the very moment we press the starter PB. It is the policy of my company to reset that failure because this is caused by an intermittent condition. I will email ATR Support and ask for clarification.

[@daoudimohammed5080]

@@FlywithMagnar verry clear answer, please let us know once you hear from ATR. Thanks in advance

[@FlywithMagnar]

Reply from ATR Flight Operations Support: "ATR allows to reset only the MAIN BAT CHG P/B if a FAULT occurs during the engine starting phase. The reset of the MAIN BAT CHG P/B is forbidden outside the starting phase."

[@FI2006007]

@@FlywithMagnar thank you Magnar. Keep safe

[@lanzp.8449]

What does pcm means?

[@cintula82]

Is it normal or am i doing something wrong in the sim? During taxiing with idle throttle i got low dc power

[@FlywithMagnar]

The ATR model in MSFS is wrong. Until the next update is ready, you must keep the power levers slightly above GI.

[@user-qd1yp5bn2q]

Does the TRU charge batteries? If not, then why in case of battery failure, even if TRU is supplying EMER buses, aircraft loses electrical power?

[@FlywithMagnar]

No, the TRU does not charge the batteries. In case of battery failure, the TRU still supplies the EMER bus, ESS bus and both STBY buses. Both HOT BAT buses are lost.

[@user-qd1yp5bn2q]

@@FlywithMagnar Thanks for the reply!

[@aeronauticgeek4432]

Are there more parts to this avionics system?

[@FlywithMagnar]

This video is an introduction to the electrical system. I have made an introduction to the avionics here: kzbin.info/www/bejne/hqrTf4qYbtWlb7s

[@aeronauticgeek4432]

@@FlywithMagnar thank you... And are there more parts to the electric system? Happy new year captain

[@shivapoudel9059]

why cant we get dc gen one and two powered through ext power ,with battery switch off?

[@FlywithMagnar]

No reason for that. When we want to unpower the aircraft, we select the battery switch off. That is what it's made for. The GPU is used to provide electrical power to the systems when the engines are shut down on the ground. When the engines are running, the generators provide this power. Routing power from the GPU to the generators will only create extra heat, which is waste of energy.

[@shivapoudel9059]

I mean to say..if battery switch is off and gpu on ..then efis on number one and number 2 goes off.why do we need to put battery on to get power supply from gpu?

[@FlywithMagnar]

@@shivapoudel9059 , the battery switch is the main electrical switch. When the battery switch is off and you connect the GPU, it will only power the CD SVCE BUS (lights in the cabin) and GND HDL BUS (refuel and cargo door operation).

[@shivapoudel9059]

@@FlywithMagnar its dc service bus right sir?..but in flight if we put the battery switch off ..does it work in same way?

[@FlywithMagnar]

@@shivapoudel9059 , yes I meant DC. I have never tried to switch off the battery switch in flight. Never will I try it.

[@douggale5962]

All this talk about redundancies and backups and bus ties and contingency handling, makes me wonder what experiences you have had with serious equipment failures.