Power set or thrust set ?

[stilton]

Curious to see, we call out ‘power set’ after take off power is reached and ‘power loss’ in the event of a significant reduction or engine failure


Never call out which engine until going through the checklist prior to shutdown


What are your call outs in this regime ?

[Intruder]

"80 knots, thrust set."

"Engine failure" or "Engine fire"

[AmarokGTI]

Regional Airline, Turboprop.

Normal ops - Capt advances power levers, calls for FO to “set power” via the CTOT system. FO engages the system and responds “Power Set” when it is. (Other call outs omitted for simplicity).

[tdracer]

Power matters for propeller aircraft. Thrust matters for jet aircraft.
Everything after that is nit-pic.

[Fursty Ferret]

*cough* TPR *cough*

[JammedStab]

Looking back at aircraft flown over the years, it does seem like power was the tuboprop wording "Max Power" and thrust was the jet terminology. Certainly thrust was never used in the turboprop world in my experience.

[A and C]

Who gives a damm ? The particular bit of mouth music you use in your SOP is of little relevance as long as the engines are correctly set for take off and both pilots understand what has happened.

[ImbracableCrunk]

You could say almost anything as long as the callout is SOP and indications are correct and checked.Make turns for V2+20!

V2+20 aye, Captain.

[ahramin]

You could say almost anything as long as the callout is SOP and indications are correct and checked.Make turns for V2+20!

V2+20 aye, Captain.
Brilliant!

[Escape Path]

Completely agree with this.

For the sake of the argument though: "Power" for both DHC-6 and -8. Thrust set for A320. So yes, it seems power for turboprops and thrust for jets

[Escape Path]

Who gives a damm ? The particular bit of mouth music you use in your SOP is of little relevance as long as the engines are correctly set for take off and both pilots understand what has happened.

Completely agree with this.

For the sake of the argument though: "Power" for both DHC-6 and -8. Thrust set for A320. So yes, it seems power for turboprops and thrust for jets

[LADAN 2ALPHA]

Still on take-off thrust, anyone with an idea why we advance thrust levers to 40%, or around 50% for some jets, before setting the full takeoff thrust? Anyone know of any other reasons apart from engine thermal stabilization and making sure that both engines are spooling at the same rate? I can't seem to find any other reasons online...

[dook]

Bear in mind that a turbofan or turbojet engine at high or max thrust is producing zero power if the aeroplane is not moving, unlike a turboprop.

[JayMatlock]

Bear in mind that a turbofan or turbojet engine at high or max thrust is producing zero power if the aeroplane is not moving, unlike a turboprop.
It depends which power you are talking about.

[Vessbot]

Bear in mind that a turbofan or turbojet engine at high or max thrust is producing zero power if the aeroplane is not moving, unlike a turboprop.

You're mixing "power" measured at different places.

As far as power transmitted to the airframe, a turboprop at standstill gives the same as a jet at standstill: zero.

The power across the shaft (torque X rpm) is quite high, on the other hand.

[illini90]

We use throttle hold, thrust normal on the 737

[tdracer]

Still on take-off thrust, anyone with an idea why we advance thrust levers to 40%, or around 50% for some jets, before setting the full takeoff thrust? Anyone know of any other reasons apart from engine thermal stabilization and making sure that both engines are spooling at the same rate? I can't seem to find any other reasons online...

It's because turbine engines accelerating from idle tend to accelerate slowly and often at different rates. If you set takeoff thrust (or power) from idle, if the turbines don't accelerate at the same rate you can get a massive thrust asymmetry and associated yaw - much more than can be overcome by the rudder at low speed. Either abort, or go off the side...
By advancing the thrust levers to some mid-thrust position gets away from that slow idle response regime that is characteristics of turbines. So the procedure is to set a mid N1/EPR, let the engines stabilize, then advance to TO (or engage autothrottle). Simples.

[KenV]

Still on take-off thrust, anyone with an idea why we advance thrust levers to 40%, or around 50% for some jets, before setting the full takeoff thrust? Anyone know of any other reasons apart from engine thermal stabilization and making sure that both engines are spooling at the same rate? I can't seem to find any other reasons online...To avoid assymmetric spool up of the engines and the resulting yaw at low airspeed where the rudder has no power.

[rogerg]

We used to use "smoke on" BAC1-11

[Pugilistic Animus]

Forget power and thrust...just say "Pour on the coals":}

British pilots taught me that one

[Tee Emm]

To avoid asymmetric spool up of the engines and the resulting yaw at low airspeed where the rudder has no power.

But rudder pedal nose wheel steering is effective if that happens.
According to the CFM 56 OperationManual for the engine there is a 3 second tolerance in CFM 56 series engines between ground idle of 22% N1 and 40% N1 for the same rate of throttle opening. But between 40% N1 and full power there is only a one second tolerance in rate of spool up for same rate of throttle movement.

This means if the pilot selects TOGA from idle thrust of 22% N1 and one of those engine takes up its three second tolerance between 22% N1 and 40% N! while the other engine spools up to take off thrust without any delay, the aircraft would initially very likely yaw strongly towards the "slower" engine and cause the pilot to lose directional control in the first few seconds of the take off roll due strong asymmetric thrust.

But by first opening the thrust levers to approximately 40% N1 with the brakes off and checking equal rate of spool up then selecting TOGA either manually or via autothrottle the chances of a directional control problem early in the take off roll happening is reduced.

At least one Asian operator I know includes an extra SOP where the PM is required to call "STABLE" when the N1's are equal at 40%N1 during the initial part of the take off roll. This is not a Boeing required call. On receiving the call of "STABLE", the PF selects TOGA and the thrust levers advance as advertised.
On one occasion during simulator training, the PM was quietly advised not to say anything as the PF pushed open the throttles to 40% N1. The PF proceeded to trundle down the runway at 40% N1. Passing the 1000 ft marker still at 40% N1 and nearing 50 knots IAS, the PF looked accusingly across the cockpit to his PM and said "Hurry up - you have forgotten to call "Stable" Readers can draw their own conclusions..

A common mistake made by pilots is to push the thrust levers to half way up the throttle quadrant on brakes release in a mistaken attempt to hurry up the rate of engine spool up which is relatively slow between ground idle and 40% N1 so by the time they press TOGA during an autothrottle take off the N1 are around 60% to 70% N1. This may have its genesis in pilots having previously operated the P&W JT8D engine where the mantra was "Stand'em up" and throttles pushed up to the vertical position to check spool up before applying full thrust on take off.

Having said that, the Boeing 737 FCTM discusses touch and go landings and states" After touch down, the instructor selects flaps 15, sets stabiliser trim, ensures speedbrakes are down, and at the appropriate time instructors the trainee to move the thrust levers to approximately the vertical position (so engines stabilize before applying go-around thrust). When the engines are stabilised the instructor instructs the trainee to set thrust.

The assumed reason for the difference between setting 40%N1 from ground idle of 22% N1 to ensure equal spool up at the low speed following brakes release, and the touch and go where thrust levers are set to vertical to ensure engines stabilised before selecting GA power, is the relatively high speed at the time the touch and go actions are commenced and therefore ample rudder control available to control any asymmetric swing.

[FE Hoppy]

Lots of aircraft require a stable call. It's to avoid assymetic thrust which in some cases will cause ATTCS (APR) to activate making things even worse.

Power = Propshaft
Thrust = Jet