TinPusher007 From United States of America, joined Feb 2005, 963 posts, RR: 2 Posted (5 years 6 months 5 days 6 hours ago) and read 2033 times:
Many modern jets can de-rate their take-off power for given conditions. My question is when a go-around is initiated and the TO/GA button is hit, are the engines putting out max thrust or whatever the take-off was de-rated to?
"Flying isn't inherently dangerous...but very unforgiving of carelessness, incapacity or neglect."
Canyonblue737 From United States of America, joined Aug 2006, 29 posts, RR: 0 Reply 1, posted (5 years 6 months 5 days 6 hours ago) and read 2025 times:
They are producing calculated go-around thrust. This is a different number than both a derated takeoff or a max takeoff thrust setting. It is also different from emergency/max thrust which is even higher.
Bri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 4 Reply 2, posted (5 years 6 months 5 days 6 hours ago) and read 2008 times:
Go around power is not de-rated takeoff thrust. But it's not always a button (except on MSFS.) On the 777, for example, it's a detent at the top of the range of throttle travel. I can't seem to find a good picture of it, but I remember it well from the simulator. I think on most FADEC planes, you just firewall the throttles (or press the go-around button, if there is one) and you'll get go-around power. There's probably a little more caution involved on older, non-FADEC birds to avoid overspeeding/overtemping an engine, but I'm not too sure.
I believe one of the conditions for a de-rated takeoff includes having full thrust available if it becomes necessary. So, it seems de-rated takeoffs are performed with the throttle at some position less than TO/GA, so there is full thrust available.
113312 From United States of America, joined Apr 2005, 508 posts, RR: 1 Reply 3, posted (5 years 6 months 5 days 4 hours ago) and read 1964 times:
On most USA built and certified aircraft, GA Thrust is maximum rated thrust with the airspeed above 80 knots. It isn't derated. The normal MAX Takeoff Thrust is a setting to achieve rated thrust for static or rolling takeoffs and that setting is valid so long as it is achieved prior to 80 knots.
MCT (Maximum Continuous Thrust) is a setting allowed for continueous use during an abnormal or emergency situation and is a higher thrust value than normal Climb thrust.
Bri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 4 Reply 4, posted (5 years 6 months 5 days 4 hours ago) and read 1957 times:
I'm curious now as to how GA Thrust is selected on a non-FADEC engine. Here's a shot of a 727 departing a short runway in Africa. The caption makes it sound like they just barely made it, so we can assume full thrust T/O power was selected. You can see the three throttle handles all differ from each other, almost an entire knob width between #1 and #3. When it's time to go around, you need full power NOW. How difficult is it to select full power without damaging an engine on a plane like this?
EssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2 Reply 5, posted (5 years 6 months 5 days 4 hours ago) and read 1953 times:
Among the first three responses, there seems to be some disagreement.
The first thing that is necessary is to specify the particular a/c and powerplant option. I agree with CanyonBlues's statements, which is then to say I disagree with this one:
Quoting 113312 (Reply 3): On most USA built and certified aircraft, GA Thrust is maximum rated thrust with the airspeed above 80 knots. It isn't derated.
On the 737, the fist toga push gives go around thrust, the 2nd click provides max thrust available.
Quoting Bri2k1 (Reply 4): I'm curious now as to how GA Thrust is selected on a non-FADEC engine.
On the 727, this is done via a target EPR setting, the same thing the FADEC would have done.
2H4 From United States of America, joined Oct 2004, 8896 posts, RR: 66 Reply 8, posted (5 years 6 months 5 days 3 hours ago) and read 1910 times:
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Quoting Bri2k1 (Reply 7): Besides, did you look at the gauges? Or was it just time for another requisite argument here at A.net?
Good god man...relax!
All I'm doing is reminding you (and readers) that without having actually been there, all we can do is guess at the flight crew's actual intentions and actions.
You wrote "We can assume full thrust T/O power was selected", when, in my opinion, "If we assume full thrust T/O power was selected, then..." would have been a more disciplined wording.
I'm not trying to pick a fight (or argument) with you, Bri2k1. People reading Tech/Ops love accuracy and detail, and I was simply pointing out that assumptions can be risky if accuracy is desired.
Quoting Bri2k1 (Reply 7): I didn't say "it definitely happened," I said we can assume it. For the purpose of asking my question, it is a valid and necessary assumption.
My point remains that if one bases a technical question on such an assumption, any conclusions reached will be little more than educated guesses.
EssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2 Reply 10, posted (5 years 6 months 5 days 2 hours ago) and read 1886 times:
Quoting Bri2k1 (Reply 4): You can see the three throttle handles all differ from each other, almost an entire knob width between #1 and #3. When it's time to go around, you need full power NOW. How difficult is it to select full power without damaging an engine on a plane like this?
If one is about to hit something hard, the throttles get firewalled, esp in a 727. In an emergency situation, there is no time, and even less reason, to search for and set a specific power setting.
The center engine has less secondary power loading than the pod engines (think bleed/electrics in general) therefore accounting for the "lower" knob position to set a certain EPR.
CosmicCruiser From United States of America, joined Feb 2005, 2015 posts, RR: 19 Reply 11, posted (5 years 6 months 5 days 1 hour ago) and read 1862 times:
Quoting Bri2k1 (Reply 4): I'm curious now as to how GA Thrust is selected on a non-FADEC engine. Here's a shot of a 727 departing a short runway in Africa. The caption makes it sound like they just barely made it, so we can assume full thrust T/O power was selected. You can see the three throttle handles all differ from each other, almost an entire knob width between #1 and #3. When it's time to go around, you need full power NOW. How difficult is it to select full power without damaging an engine on a plane like this?
When I was flying the 727 the capt. pushed the throttles up vertical and the S/O made the final adjustments. It's not uncommon to find a little stagger in the throttles for various reasons including differing eng. wear. The 727 has bleed and a gen. On a go around the same technique applies the capt stands the throttles up and the S/O makes the small epr adjustments. It's not an emergency procedure. When we saw a BIG throttle spread we would do a throttle alignment check and maint would investigate, not uncommon.
A GPWS escape is a different story, you firewall the throttles, over temp and over speed then land.
Canyonblue737 From United States of America, joined Aug 2006, 29 posts, RR: 0 Reply 13, posted (5 years 6 months 4 days 23 hours ago) and read 1817 times:
On a 737 you have (in order of highest to lowest power setting in general)...
1. Max/Emergency (the highest thrust available, ie. firewalled to the stop)
2. Go-Around Thrust (highest thrust setting available for short duration go-around with airspeed already above 80 knots.)
3. Max Takeoff Thrust (highest thrust setting available for short duration takeoff with power set before 80 knots.)
4. Max Continuous Thrust (highest thrust setting for unlimited duration during ABNORMAL flight situations.)
5. Max Climb Thrust (highest thrust setting for climb of unlimited duration during normal flight situations.)
6. Max Cruise Thrust (highest thrust setting for cruise of unlimited duration during normal flight situations.)
7. De-rated Takeoff Thrust (widely varies based on situation, but this can be nearly as high as Max Takeoff Thrust or well below Max Cruise thrust.)
All except for 1 can be found in some facet in the FMC and commanded via auto throttles or by hand with a power caret that sets itself on the N1 guages.
EssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2 Reply 14, posted (5 years 6 months 4 days 22 hours ago) and read 1806 times:
But no hydraulic pump (I may need to get my old manuals out) but there is a significant reason for the different TLA in order to achieve the same epr, comparing #s 1 and 3 vs #2...
CosmicCruiser From United States of America, joined Feb 2005, 2015 posts, RR: 19 Reply 15, posted (5 years 6 months 4 days 21 hours ago) and read 1787 times:
Quoting EssentialPowr (Reply 14): but there is a significant reason for the different TLA in order to achieve the same epr, comparing #s 1 and 3 vs #2...
That's true but I don't recall there being any "significant" diff. and the post referred to throttle stagger which I said was for the most point normal. I definitely remember seeing throttles staggered enough that on final app. you were twisting your hand around trying to add or subtract power and still keep them even. Ah yes the good old days!!
EssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2 Reply 16, posted (5 years 6 months 4 days 19 hours ago) and read 1762 times:
Quoting CosmicCruiser (Reply 15): That's true but I don't recall there being any "significant" diff. and the post referred to throttle stagger which I said was for the most point normal.
Negative; there absolutely is a significant differrence. In a normal config for the 727, the #s 1 and 3 engines are supplying bleed air, the # 2 engine is not.
The tables for the -7, -15, -17 and -17APR show takeoff and climb EPR corrections for the #2 as compared to the #s 1 and 3 for engine anti ice, engine and wing...typically of .04 - .05 EPR less for the #2 as compared to #s 1 and 3.
Therefore, on perfectly rigged and matched throttles, there will be, by definition, a difference in throttle position b/t #s 1,3 and 2, on the above powered 727s. I don't think a -9 powered a/c would deviate.
CosmicCruiser From United States of America, joined Feb 2005, 2015 posts, RR: 19 Reply 18, posted (5 years 6 months 4 days 11 hours ago) and read 1651 times:
Quoting EssentialPowr (Reply 16): ...typically of .04 - .05 EPR less for the #2 as compared to #s 1 and 3.
Not to belabor the point nor get into a pi**ing contest I don't consider that a big enough deal to address the original post about throttle stagger. Take care, CC
EssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2 Reply 19, posted (5 years 6 months 1 day 2 hours ago) and read 1425 times:
Quoting CosmicCruiser (Reply 18): Not to belabor the point nor get into a pi**ing contest I don't consider that a big enough deal to address the original post about throttle stagger.
Copy; but if it is significant enough to be in the pubs, then it is a significant difference.
ImperialEagle From United States of America, joined Jan 2006, 1102 posts, RR: 15 Reply 20, posted (5 years 6 months 1 day 1 hour ago) and read 1403 times:
I live very close to ATL. In the past year or so TO/GA's have seen a marked increase-----many of them passing over my house towards the north side of the field.
Many of the engines on the planes can be heard "hunting" for the correct setting. I can hear the N1 spooling up and down trying to find the right setting. Sounds unusual, but I am used to it now. Seems like this occurs only on "heavies".
"If everything seems under control, you're just not going fast enough!"
Canyonblue737 From United States of America, joined Aug 2006, 29 posts, RR: 0 Reply 21, posted (5 years 6 months 1 day ago) and read 1385 times:
Quoting HAWK21M (Reply 17):
Would Emergency Thrust refer to as in IFSD.
regds
MEL
Not entirely sure of your question. Emergency thrust is thrust levers full forward, the very maximum they will produce. Some people also call this "Max thrust" or "Radar Thrust." In the event of an in flight shut down you would initially go to Max Continuous (well below Emergency thrust) and then less if possible.
Emergency thrust is in general reserved for Stall Recovery, Terrain Avoidance maneuvers and anytime you think you are about to hit something hard.
Pihero From France, joined Jan 2005, 2888 posts, RR: 69 Reply 22, posted (5 years 6 months 22 hours ago) and read 1353 times:
Quoting ImperialEagle (Reply 20): Many of the engines on the planes can be heard "hunting" for the correct setting. I can hear the N1 spooling up and down trying to find the right setting. Sounds unusual, but I am used to it now. Seems like this occurs only on "heavies".
That sound is more the resultant "beat frequency -ies " that the accelerating fans are producing between themselves as they are not yet synchronised during this phase.
Quoting AC320tech (Reply 9): On the Airbus's you have the TO/GA buttons and then there is 2 detents. One is FLX/CLB and the other is TO/GA.
You'll have to qualify that.On the 320 family,the 340, you have, in order of increasing forward thrust four detents :
-idle
-Max climb (CL)
-Max CONT and Flex TO (MCT & FLX)
-Max TO and Go Around (T.O & GA)
There is NO GA button.
AC320tech From Canada, joined Jul 2006, 197 posts, RR: 1 Reply 23, posted (5 years 6 months 8 hours ago) and read 1245 times:
Quoting Pihero (Reply 22): You'll have to qualify that.On the 320 family,the 340, you have, in order of increasing forward thrust four detents :
-idle
-Max climb (CL)
-Max CONT and Flex TO (MCT & FLX)
-Max TO and Go Around (T.O & GA)
There is NO GA button.
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