A/T goes to TO mode on takeoff but then suddenly reduces power

[Shom]

Hi,

Today during the takeoff roll in the E195 the throttles moved forward automatically (after arming the A/T and pressing the TOGA button).

However after about 10 seconds when around 80 knots the engine throttles went back for no reason so I had to manually override them to complete the takeoff run.

What could cause this?

[dahsteak]

I have had this happen. It seems the AT goes from TO mode to the HOLD mode. I've found that if you manually increase your throttle when the AT is grabbing them it works out. Technically your throttle position should be changing...

[scoobflight]

4 hours ago, Shom said:

Hi,

Today during the takeoff roll in the E195 the throttles moved forward automatically (after arming the A/T and pressing the TOGA button).

However after about 10 seconds when around 80 knots the engine throttles went back for no reason so I had to manually override them to complete the takeoff run.

What could cause this?

after engine run-up (about 50%) did you move the your controllers throttle(s) to full forward?  this is how the FADEC is modeled.

Manual page 63:

Quote

TAKEOFF AND IN-FLIGHT THRUST
Simulation of the throttle control in-flight by the FADEC and autothrottle systems requires that your joystick/yoke/throttle quadrant thrust lever be in the full-forward position after engine run-up and prior to takeoff.  Unless the pilot chooses to control thrust, it is normal procedure for throttle control to be managed by the aircraft's computers.

(note: the above I correct the typo at the end of the first sentance that seems to have made its way into the manual - oops)

 

this procedure is also covered on manual page 73 -

Quote

While keeping the brakes engage advance the throttles for an N1 thrust of 45-50%.Allow the engines to stabilize for a few seconds, release the brakes and then move your throttle controller full forward to activate the autothrottle and engine FADEC logic. NOTE: you will not be adjusting the throttle levers again until you approach the landing runway at KRDU

 

[Shom]

5 hours ago, scoobflight said:

after engine run-up (about 50%) did you move the your controllers throttle(s) to full forward?  this is how the FADEC is modeled.

Manual page 63:

(note: the above I correct the typo at the end of the first sentance that seems to have made its way into the manual - oops)

 

this procedure is also covered on manual page 73 -

 

@scoobflight understood so why do the throttles move automatically forward after reaching a certain N1 value? What is the point of me pushing the throttles forward as well?

I remember seeing before release a YT video shared by a beta tester (and pilot) who said the throttles advance on their own

[Shom]

9 hours ago, dahsteak said:

I have had this happen. It seems the AT goes from TO mode to the HOLD mode. I've found that if you manually increase your throttle when the AT is grabbing them it works out. Technically your throttle position should be changing...

That is what I did

[jamieleon1]

Shom are you pressing the TOGA button on the throttles after you finish setting up the TRS page in the FMC? And verifying you see ROLL/TO on your PFD before engaging autothrottle? 

[FeelThere_Vic]

You need to move it all the way because your hardware is not moving along with the coded lever and can send noises back to code.

Vic

[Shom]

45 minutes ago, jamieleon1 said:

Shom are you pressing the TOGA button on the throttles after you finish setting up the TRS page in the FMC? And verifying you see ROLL/TO on your PFD before engaging autothrottle? 

Correct

 

24 minutes ago, FeelThere said:

You need to move it all the way because your hardware is not moving along with the coded lever and can send noises back to code.

Vic

I use simply a Logitech joystick.

It did not reproduce in several E175 takeoffs I did beforehand

[scoobflight]

1 hour ago, Shom said:

I use simply a Logitech joystick.

the throttle lever on the joystick still needed to be moved to full forward for the same reasons Vic noted.

[Matty260191]

I just had a very turbulent departure fro EGLC 27 A/T on on the ground as it should be in TO1 mode no FLEX advanced throttles to full as i always do. as i get airborne i hear the engines throttle back when the shouldn't be. i had to very quick goto manual throttles to save the flight. E170 ALT/VS(maybe why?) AND LNAV SELECTED AP OFF A/T ON THROTTLES FULL i will send a clip in a moment. seems like the issue described above and hasn't happened before. maybe has to do with the turbulence? I was trying using ALT/VS today since in VNAV on transition to climb we get that awful steep climb. this may be the reason.

[Matty260191]

ATTCS Was green but went white as soon as i was airborne if that helps?

[Matty260191]

 

[scoobflight]

2 hours ago, Matty260191 said:

advanced throttles to full as i always do. as i get airborne i hear the engines throttle back when the shouldn't be.

have you duplicated the issue?  is it possible you knocked the throttle controller?  you stated you moved the throttles forward after A/T disconnected?

[Matty260191]

They were fully forward on takeoff not knocked. I moved them once i realised the throttle had dropped to try regain control. I have a feeling it was because instead of being in VNAV I was using ALT/VS to reduce the stupid high climb rate. Maybe its how it is supposed to act in thst case?

[Matty260191]

I will duplicate it tomorrow.

[Matty260191]

On 1/8/2020 at 3:12 PM, jamieleon1 said:

Shom are you pressing the TOGA button on the throttles after you finish setting up the TRS page in the FMC? And verifying you see ROLL/TO on your PFD before engaging autothrottle? 

The TOGA button is not needed to be pressed just arm the A/T then move the throttle fully forward to engage it. 

[Triholer]

Hey Matty,

It indeed has to be pressed as part of the Before Start Procedures. You have to set your FMS completely, choose the relevant speeds for you and afterwards you press the TO/GA button on ground. In that way the Autothrottle is armed for the performances entered in the FMS. You shall also compare your pitch indication on the flight director to the value displayed in your MCDU at that. 
 

However I'm not sure which Epic Load is installed on the feelthere E190 (so basically which software update of the FMS), but for the newer versions (Post-Mod LOAD 27.1) Embraer says the following: "Verify LNAV and VNAV armed on ground. Pressing TO/GA Button on ground arms LNAV and VNAV. VNAV is planned to engage according to the DEPARTURE LIMIT page settings"

Regards
Björn

[Matty260191]

Ok but when do you arm the A/T then?

 

set up FMS

Arm Lnav/Vnav

press TOGA.

then arm A/T?

then on takeoff when you fully forward the throttles does it kick in?

[Matty260191]

So when do you actually put the A/T on or does it do it itself on moving the throttles fully forward?

[Matty260191]

1 hour ago, Triholer said:

Hey Matty,

It indeed has to be pressed as part of the Before Start Procedures. You have to set your FMS completely, choose the relevant speeds for you and afterwards you press the TO/GA button on ground. In that way the Autothrottle is armed for the performances entered in the FMS. You shall also compare your pitch indication on the flight director to the value displayed in your MCDU at that. 
 

However I'm not sure which Epic Load is installed on the feelthere E190 (so basically which software update of the FMS), but for the newer versions (Post-Mod LOAD 27.1) Embraer says the following: "Verify LNAV and VNAV armed on ground. Pressing TO/GA Button on ground arms LNAV and VNAV. VNAV is planned to engage according to the DEPARTURE LIMIT page settings"

Regards
Björn

ok so armed vnav armed lnav then pressed the toga goes in to TO AT ROLL TO on the PFD then after departure should it switch itself to LNAV/VNAV

[scoobflight]

And be sure to move your yoke/throttle controller fully forward -

On 1/7/2020 at 6:19 PM, scoobflight said:

Manual page 63:

Quote

TAKEOFF AND IN-FLIGHT THRUST
Simulation of the throttle control in-flight by the FADEC and autothrottle systems requires that your joystick/yoke/throttle quadrant thrust lever be in the full-forward position after engine run-up and prior to takeoff.  Unless the pilot chooses to control thrust, it is normal procedure for throttle control to be managed by the aircraft's computers.

(note: the above I correct the typo at the end of the first sentance that seems to have made its way into the manual - oops)

 

[Matty260191]

omg read i said that what i do more than once. that is not my issue.

[Triholer]

Hey, 

Ok so from your narrative it seems the Feelthere E-Jets are the Pre-Mod Load  but that is actually more familiar to me than the upgraded vastly changed and improved FMS Loads.
[Btw. I dont have the add-on myself yet, waiting for the SP]

• The TO/GA Button only gives you T/O Pitch and Roll Mode, you can pre-select NAV for Lateral Navigation on Ground and it will come to effect at (I believe) 400ft AGL
• You select VNAV after Take-Off - a bit dependend on the operating airline - but if I remember correctly Embraer recommends 1000ft AGL
• The A/T is usually selected when lined up on the departure runway, so that you do not accidentally run into an acting ATTCS and a activation of T/O thrust prior a real need directly prior T/O Run.  

Hope that solves a bit of it 👨‍✈️

[Matty260191]

ok well all is good but it doesnt come out of takeoff mode into nav mode so you have to select vnav and lnav after departure when you want it. the aircraft also ignores speed constraints in vnav which is annoying.

[dahsteak]

3 hours ago, Triholer said:

• The TO/GA Button only gives you T/O Pitch and Roll Mode, you can pre-select NAV for Lateral Navigation on Ground and it will come to effect at (I believe) 400ft AGL

This is correct, but NAV will only show up in white below the green ROLL. In an armed state. Unfortunately the current Ejets doesn't simulate this. It currently puts the NAV in green replacing the ROLL.