Full T/O power on take off!
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ok so you are saying that when you reach thrust reduction altitude you will transition to climb power and the derate/reduced thrust story ends, right ?
here's what the 737 FCOM says about pushing TOGA,
"After LIFT-OFF:
• the A/T remains in THR HLD until 800 feet RA. A/T annunciation then
changes from THR HLD to ARM and reduction to climb thrust can be
made by pushing the N1 switch.
Note: During a reduced thrust takeoff, a second press of the TO/GA switch
below 800 feet RA will change the thrust limit mode to GA and N1
reference bugs to increase to full GA thrust, thrust levers will not be in
motion. A second press of the TO/GA switch above 800 feet RA, thrust
levers advance toward full GA thrust.
• automatic reduction to climb thrust occurs upon reaching the selected
thrust reduction altitude which is shown on the FMC CDU TAKEOFF
REF page 2/2 during preflight, or when the airplane levels off in ALT
HOLD or VNAV PTH. Pilot entries can be made to override the default
value. Allowable entries are 800 feet to 9999 feet
• flight director engaged status is terminated by engaging an autopilot in
CMD (CMD replaces FD in A/P status display)
• pitch engages in LVL CHG and pitch mode FMA is MCP SPD unless
another pitch mode has been selected
• MCP IAS/Mach display and airspeed cursor change to V2 + 20 knots
• roll mode engages in HDG SEL unless another roll mode has been
selected.
To terminate the takeoff mode below 400 feet RA, both F/D switches must be
turned OFF. Above 400 feet RA, selection of another pitch mode or engaging an
autopilot will terminate the takeoff mode; other F/D roll modes can be also
selected."
here's what the 737 FCOM says about pushing TOGA,
"After LIFT-OFF:
• the A/T remains in THR HLD until 800 feet RA. A/T annunciation then
changes from THR HLD to ARM and reduction to climb thrust can be
made by pushing the N1 switch.
Note: During a reduced thrust takeoff, a second press of the TO/GA switch
below 800 feet RA will change the thrust limit mode to GA and N1
reference bugs to increase to full GA thrust, thrust levers will not be in
motion. A second press of the TO/GA switch above 800 feet RA, thrust
levers advance toward full GA thrust.
• automatic reduction to climb thrust occurs upon reaching the selected
thrust reduction altitude which is shown on the FMC CDU TAKEOFF
REF page 2/2 during preflight, or when the airplane levels off in ALT
HOLD or VNAV PTH. Pilot entries can be made to override the default
value. Allowable entries are 800 feet to 9999 feet
• flight director engaged status is terminated by engaging an autopilot in
CMD (CMD replaces FD in A/P status display)
• pitch engages in LVL CHG and pitch mode FMA is MCP SPD unless
another pitch mode has been selected
• MCP IAS/Mach display and airspeed cursor change to V2 + 20 knots
• roll mode engages in HDG SEL unless another roll mode has been
selected.
To terminate the takeoff mode below 400 feet RA, both F/D switches must be
turned OFF. Above 400 feet RA, selection of another pitch mode or engaging an
autopilot will terminate the takeoff mode; other F/D roll modes can be also
selected."
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and just to keep king happy heres what the 777 FCOM says about pushing TOGA
On the ground:
Push –
• below 50 knots and flaps out of up, activates autothrottle in THR REF
mode at thrust limit selected on THRUST LIMIT page. If not pushed
below 50 knots, autothrottle operation is inhibited until reaching 400 feet
altitude
• pushing either switch above 80 knots disarms LNAV and VNAV
In flight:
Push (after lift-off with takeoff thrust limit displayed) –
• removes takeoff and climb derates and assumed temperature thrust
reduction
• A/T in HOLD, activates A/T in THR REF mode
• disarms AFDS modes
• between 50 feet and 400 feet, selects TO/GA roll mode
• above 400 feet, selects TO/GA roll and pitch modes
Push (on approach with flaps out of up or glideslope captured) –
• activates autothrottle in THR mode with GA thrust limit displayed
• disarms AFDS modes
• selects TO/GA roll and pitch modes
XXXXX - (a/c registrations)
• arms or engages LNAV if an LNAV path is available
• second push – activates autothrottle in THR REF mode
On the ground:
Push –
• below 50 knots and flaps out of up, activates autothrottle in THR REF
mode at thrust limit selected on THRUST LIMIT page. If not pushed
below 50 knots, autothrottle operation is inhibited until reaching 400 feet
altitude
• pushing either switch above 80 knots disarms LNAV and VNAV
In flight:
Push (after lift-off with takeoff thrust limit displayed) –
• removes takeoff and climb derates and assumed temperature thrust
reduction
• A/T in HOLD, activates A/T in THR REF mode
• disarms AFDS modes
• between 50 feet and 400 feet, selects TO/GA roll mode
• above 400 feet, selects TO/GA roll and pitch modes
Push (on approach with flaps out of up or glideslope captured) –
• activates autothrottle in THR mode with GA thrust limit displayed
• disarms AFDS modes
• selects TO/GA roll and pitch modes
XXXXX - (a/c registrations)
• arms or engages LNAV if an LNAV path is available
• second push – activates autothrottle in THR REF mode
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I don't fly a boeing, but E170/E190's.
The posters question seems pretty reasonable. We have TO-1, TO-2 and TO-3, all of which we can flex.
Most of the guys in work are surprised to learn that if we use TO-3 with a flex, it does not matter how hard or how far we push the thrust levers, we are not going to get any more thrust than TO-3 no flex, with 2 exceptions.
1. Windshear will give WSHR thrust.
2. Engine failure will give us Reserve power, but only TO-3 reserve.
If we have completley messed up our performance, and the end of the runway, or an obstacle is rapidly approaching and we wan't to get away from TO-3 flex to TO-1, then some very quick FMS programming would be required.
The posters question seems pretty reasonable. We have TO-1, TO-2 and TO-3, all of which we can flex.
Most of the guys in work are surprised to learn that if we use TO-3 with a flex, it does not matter how hard or how far we push the thrust levers, we are not going to get any more thrust than TO-3 no flex, with 2 exceptions.
1. Windshear will give WSHR thrust.
2. Engine failure will give us Reserve power, but only TO-3 reserve.
If we have completley messed up our performance, and the end of the runway, or an obstacle is rapidly approaching and we wan't to get away from TO-3 flex to TO-1, then some very quick FMS programming would be required.
Sorry for the thread creep.
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@FE Hoppy....no worries mate. Knowledge always welcome,whether on or off topic. No thread creep there(tried a gentle reminder earlier...lol).
Airyana-Thanks for the reproduction of the Fcom.
Nonetheless,if you read my original query,it was quite clearly with regards to availability(or otherwise)of full non derated thrust during T/O roll. Granted I didn't give a speed but I take it,it was understood as being above 80 kts. Application of toga > 80kts will disarm the pitch and roll modes and go to toga mode. But what happens to the actual thrust of the airplane? And i'm not talking about just the Fma readout. The actual thrust...
I'm assuming it will go to max derated power. But the honest question was, is there any way to get max un-derated thrust when on ground on T/O roll and above 80 kts...
Hope this clears the air.
Airyana-Thanks for the reproduction of the Fcom.
Nonetheless,if you read my original query,it was quite clearly with regards to availability(or otherwise)of full non derated thrust during T/O roll. Granted I didn't give a speed but I take it,it was understood as being above 80 kts. Application of toga > 80kts will disarm the pitch and roll modes and go to toga mode. But what happens to the actual thrust of the airplane? And i'm not talking about just the Fma readout. The actual thrust...
I'm assuming it will go to max derated power. But the honest question was, is there any way to get max un-derated thrust when on ground on T/O roll and above 80 kts...
Hope this clears the air.
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I-ford-
The qualifying statment to what you just quoted is:
"Maximum N1 represents the maximum rated thrust available from the engine. The EEC continuously computes maximum N1."
This statment precedes your quote:
"Maximum rated thrust is available in any phase of flight by moving the thrust levers to the full forward positions."
The Maximum N1,on a derated,assumed temperature take off would be the maximum thrust available with that derate and not the max un-derated thrust. So,if u advance TL's to full fwd position you still get only max derate thrust (which is what the EEC's have computed anyways and shows on your DU).
Cheers..
The qualifying statment to what you just quoted is:
"Maximum N1 represents the maximum rated thrust available from the engine. The EEC continuously computes maximum N1."
This statment precedes your quote:
"Maximum rated thrust is available in any phase of flight by moving the thrust levers to the full forward positions."
The Maximum N1,on a derated,assumed temperature take off would be the maximum thrust available with that derate and not the max un-derated thrust. So,if u advance TL's to full fwd position you still get only max derate thrust (which is what the EEC's have computed anyways and shows on your DU).
Cheers..
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i must say i am nor a 737 neither a 737 driver but this all sounds strange.
here is a good description of flexing and derating on example 737
A temporary form of de-rating known as a "T/O de-rate" is accessible through the FMC on TAKEOFF REF 2/2 or N1 LIMIT (NG's) but this is prohibited by some operators. The T/O de-rates (TO-1 & TO-2) can be 10 to 20%. It follows that an engine may be de-rated and also be using reduced thrust in which case you could be taking off at Full power -20% -25% = 60% of the full power of the engine - scary thought! Note that a T/O de-rate can overridden by firewalling the thrust levers; this action will give the thrust rating shown on the IDENT page.
from b737.org.uk
you have to consider if the thrust was derated by a technican on ground ( i.e mixing two different rated engines) or by pilot via fms.
in the first case the "full" rated thrust is not available by pilot action since its a permanent derating ( e.g the 737NG can be supplied by 22K 24K 26K etc engines which are basicly the same but with different max power settings)
the second scenario is a derating via fms by the pilot- and here in every me known airplane disengaging autothrust and firewalling the levers will give maximum certified thrust of the engine cancelling any thrust reductions that had been set for a reduced takeoff.
i cannot imagine on a 777 you cannot cancel a pilot chosen TO derated thrust by firewalling.
you also have to consider if its a fadec controlled engine or not. fadec will give you always the "only" maximum of the engine without exeeding limits.
at non fadec planes you of course have to be very careful with simply firewalling.
at the bae146 i have flown there is a thrust modulation system in which you set a flex n1 by tables.
you have simulatan a bug on the n1 gauge where the n1ref- the maximum allowable for the temperature and elevation is shown. in every case simply pushing the levers forward will give you the un-derated thrust ( bae146)
firewalling on the bae146 may toast the engines, you will exeed EGT limits.
there was due to the OM one exeption : wind shear.
there was written that at a windshear where even at full rated thrust and stickshaker activated the plane has negative rate of climb and ground contact is likely push the power levers full forward regardless of EGT redline.
after doing this return to max continus as soon as possible , land as soon as possible and all engines has to be removed and inspected before next flight.
here is a good description of flexing and derating on example 737
A temporary form of de-rating known as a "T/O de-rate" is accessible through the FMC on TAKEOFF REF 2/2 or N1 LIMIT (NG's) but this is prohibited by some operators. The T/O de-rates (TO-1 & TO-2) can be 10 to 20%. It follows that an engine may be de-rated and also be using reduced thrust in which case you could be taking off at Full power -20% -25% = 60% of the full power of the engine - scary thought! Note that a T/O de-rate can overridden by firewalling the thrust levers; this action will give the thrust rating shown on the IDENT page.
from b737.org.uk
you have to consider if the thrust was derated by a technican on ground ( i.e mixing two different rated engines) or by pilot via fms.
in the first case the "full" rated thrust is not available by pilot action since its a permanent derating ( e.g the 737NG can be supplied by 22K 24K 26K etc engines which are basicly the same but with different max power settings)
the second scenario is a derating via fms by the pilot- and here in every me known airplane disengaging autothrust and firewalling the levers will give maximum certified thrust of the engine cancelling any thrust reductions that had been set for a reduced takeoff.
i cannot imagine on a 777 you cannot cancel a pilot chosen TO derated thrust by firewalling.
you also have to consider if its a fadec controlled engine or not. fadec will give you always the "only" maximum of the engine without exeeding limits.
at non fadec planes you of course have to be very careful with simply firewalling.
at the bae146 i have flown there is a thrust modulation system in which you set a flex n1 by tables.
you have simulatan a bug on the n1 gauge where the n1ref- the maximum allowable for the temperature and elevation is shown. in every case simply pushing the levers forward will give you the un-derated thrust ( bae146)
firewalling on the bae146 may toast the engines, you will exeed EGT limits.
there was due to the OM one exeption : wind shear.
there was written that at a windshear where even at full rated thrust and stickshaker activated the plane has negative rate of climb and ground contact is likely push the power levers full forward regardless of EGT redline.
after doing this return to max continus as soon as possible , land as soon as possible and all engines has to be removed and inspected before next flight.
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you also have to consider if its a fadec controlled engine or not. fadec will give you always the "only" maximum of the engine without exeeding limits.
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@aerobat77
Sorry but you are misinformed. There are several installations where having selected a de-rated TO thrust the pilot cannot override the selection during the TO. To do so could render the aeroplane uncontrollable as has be explained in this thread.
Sorry but you are misinformed. There are several installations where having selected a de-rated TO thrust the pilot cannot override the selection during the TO. To do so could render the aeroplane uncontrollable as has be explained in this thread.
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This is the false information most pilots do not understand COMPLETELY, on a FADEC engine you can not exceed the limits the company you work for has provided to you. The engine is often rated for much more and certified for allot more than rated thrust, you just have no access to that thrust.
well, yes. today with all the electronics the same engine may be rated in different maximum thrusts, thats right- like eg. the cfm56-7b which is available in a wide range of rated thrust. and at low temperatures and a flat rated engine this maximum thrust maybe reached far below redlines in EGT or N1. but i think the discussion is how to restore the maxmimum retad thrust from a pilot selected reduced takeoff - and the reducing starts always at the maximum available at a given engine on your plane , not from the highest certified on the engine model family.
you may have on a b737 a cfm56-7b 24K engine - the same core engine produces in another adjustment 26K on another 737. in this case you will never have access to more than 24K, true- but i think it should always be possible to restore your 24K when you derated and started a takeoff with lets say 20K of thrust.
@ FE hoppy: well, like said i,m not a 777 driver, but it sound truly strange. the Vmcg as well Vmca are related to maximum rated thrust on the engine under your wings , so where you loose control applying the max rated when you suddenly need? also all single engine performance is related to maximum rated thrust - you can throw you climb gradients all away when you start derated , one engine fails and you cannot restore max rated power from the other... or do we speak about something different?
like said- we do not discuss a permanent thrust rating setting by the manufacturer -we discuss a pilot selected reduced takeoff rating.
but i may be wrong even when i cannot imagine.
well, yes. today with all the electronics the same engine may be rated in different maximum thrusts, thats right- like eg. the cfm56-7b which is available in a wide range of rated thrust. and at low temperatures and a flat rated engine this maximum thrust maybe reached far below redlines in EGT or N1. but i think the discussion is how to restore the maxmimum retad thrust from a pilot selected reduced takeoff - and the reducing starts always at the maximum available at a given engine on your plane , not from the highest certified on the engine model family.
you may have on a b737 a cfm56-7b 24K engine - the same core engine produces in another adjustment 26K on another 737. in this case you will never have access to more than 24K, true- but i think it should always be possible to restore your 24K when you derated and started a takeoff with lets say 20K of thrust.
@ FE hoppy: well, like said i,m not a 777 driver, but it sound truly strange. the Vmcg as well Vmca are related to maximum rated thrust on the engine under your wings , so where you loose control applying the max rated when you suddenly need? also all single engine performance is related to maximum rated thrust - you can throw you climb gradients all away when you start derated , one engine fails and you cannot restore max rated power from the other... or do we speak about something different?
like said- we do not discuss a permanent thrust rating setting by the manufacturer -we discuss a pilot selected reduced takeoff rating.
but i may be wrong even when i cannot imagine.
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the Vmcg as well Vmca are related to maximum rated thrust on the engine under your wings , so where you loose control applying the max rated when you suddenly need? also all single engine performance is related to maximum rated thrust
- 90B
- TO-1
- TO-2
The takeoff performance is based on whichever of these 3 ratings you have chosen to use on that day, the associated VMC speeds are based on THAT chosen rating and not on 90B (unless you are using 90B)
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when the vmcg and vmca is truly recalculated due to the choosen derating on a 777 it may make sense that you indeed cannot restore maximum underated power in this case.
that would be absolutely new for me, at no airplane i drove it was that case but when it indeed is so at this plane it would make sense.
but what for (single engine) perfomnace tables? do you have three complete sets for 90B TO1 and TO2?
interesting!
that would be absolutely new for me, at no airplane i drove it was that case but when it indeed is so at this plane it would make sense.
but what for (single engine) perfomnace tables? do you have three complete sets for 90B TO1 and TO2?
interesting!
Aerobat
As has been posted here numerous times, using a "derate"is EXACTLY like installing a different engine on the airframe. All performance is now computed at the derated thrust, this is quite different than with "reduced" thrust settings (assumed temp, for example). Here all the performance calcs are based on the rated power (maximum or the derate selected), so it is perfectly valid to add power from the reduced setting to the rated power without concern about Vmcg or Vmca. Dynamics of adding thrust need to be accounted for, snappy power changes maybe deatablizimg even if the actual power vs. speeds is acceptable in a stable situation.
GF
As has been posted here numerous times, using a "derate"is EXACTLY like installing a different engine on the airframe. All performance is now computed at the derated thrust, this is quite different than with "reduced" thrust settings (assumed temp, for example). Here all the performance calcs are based on the rated power (maximum or the derate selected), so it is perfectly valid to add power from the reduced setting to the rated power without concern about Vmcg or Vmca. Dynamics of adding thrust need to be accounted for, snappy power changes maybe deatablizimg even if the actual power vs. speeds is acceptable in a stable situation.
GF
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ok, you never learn enough- i did not knew that. the bae146 i have flown was not that smart, the cheyenne III i do now of course also not.
so for clarifiction : there is no way restoring 90B thrust when you once selected lets say TO2 on the 777?
so for clarifiction : there is no way restoring 90B thrust when you once selected lets say TO2 on the 777?
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So as I understand it now:
You select TO-2 for takeoff and then above 80 kts on ground u hit TOGA, u will disengage the pitch and roll modes.What if u now disconnect AT and firewall the thrust levers. What thrust will u get. Will it be Max TO-2 or Max TO.
You select TO-2 for takeoff and then above 80 kts on ground u hit TOGA, u will disengage the pitch and roll modes.What if u now disconnect AT and firewall the thrust levers. What thrust will u get. Will it be Max TO-2 or Max TO.