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-   -   Power set or thrust set ? (https://www.pprune.org/tech-log/611337-power-set-thrust-set.html)

stilton 21st Jul 2018 02:22

Power set or thrust set ?
 
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 21st Jul 2018 02:54

"80 knots, thrust set."

"Engine failure" or "Engine fire"

AmarokGTI 21st Jul 2018 06:42

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 21st Jul 2018 08:29

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

Fursty Ferret 21st Jul 2018 20:04

*cough* TPR *cough*

JammedStab 22nd Jul 2018 19:01

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 22nd Jul 2018 21:50

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 23rd Jul 2018 04:08

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 23rd Jul 2018 20:55


Originally Posted by ImbracableCrunk (Post 10203586)
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 25th Jul 2018 06:45

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 25th Jul 2018 06:46


Originally Posted by A and C (Post 10203472)
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 26th Jul 2018 16:22

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 26th Jul 2018 16:43

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 26th Jul 2018 17:24


Originally Posted by dook (Post 10206856)
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 26th Jul 2018 17:52


Originally Posted by dook (Post 10206856)
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 26th Jul 2018 21:07

Power
 
We use throttle hold, thrust normal on the 737

tdracer 27th Jul 2018 01:36


Originally Posted by LADAN 2ALPHA (Post 10206834)
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 31st Jul 2018 19:49


Originally Posted by LADAN 2ALPHA (Post 10206834)
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 1st Aug 2018 16:17

We used to use "smoke on" BAC1-11

Pugilistic Animus 2nd Aug 2018 07:25

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

British pilots taught me that one


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