PDA

View Full Version : Go Around N1 values in the Performance Card


mr.crocodile
12th Mar 2015, 17:59
Hi, in the Ryanair loadsheet, below the section where to insert pax number, there is the performance section with Flaps, Speeds and N1 values.
During the preflight preparation, in the FMC N1 Limit page on the upper right side we can find the full N1 value and after selection of the reduction/derate in the same position we have the reduced N1 value so, if I correctly understood, this two values can be reported in the related loadsheet section (N1 [F] and N1 [R]). To fill in the Go Around N1 value just above this two other values, I did not understand where to find it in the FMC (if so) during the preflight.

I found an old 737 Airone performance card and even there I found Normal, Reduced and Go-Around EPR/N1 values to be filled in. Why is the Go Around N1 so necessary before take off?

B737900er
12th Mar 2015, 18:56
The GA N1 value will be a reduced value (unknown) to give you a rate of climb 1500-2000fpm with the first push of the TOGA buttons. A second push will give you a full rated thrust Go around. This N1 value can be seen on the N1 gauge with a green carrot (>) when G/A is announced OR on the N1 limit page.

If you would like to find out the Go Around value before departure you could look in the Performance Inflight tables in the FCOM 1 manual.

737aviator
13th Mar 2015, 18:13
For the purposes of this load sheet this is the full 26k (or 27k if you've got fancy engines) figure, and is the thrust if no derate or ATM is used, or the full go around thrust (2 presses of TOGA). Then in the other boxes the N1 for the selected derate (24k or 22k, if any) is recorded, and then the N1 for the assumed temp (if any) is recorded.

JeroenC
14th Mar 2015, 15:38
Both replies are correct, but I second the OP question: what's the relevance on TAKEOFF?
TO is not a GA, and you would not exceed your fixed derate unless in emergency, and in that case I firewall the TLs anyway.

B737900er
14th Mar 2015, 23:39
JeroenC- If your fire wall your TL's on a derate (no assume temp) you will be breaking a limitation. Your Vspeeds, especially VMCG will be based on that derate, fire walling will cause you some directional issues if you lose an engine.

Once airborne, do what you have to do, be it the WEM or EGPWS manoeuvre.

JeroenC
16th Mar 2015, 08:56
Hi B737, I'm aware of that, thats why I said in an emergency.
Any ideas about the answer to the question?

Cough
16th Mar 2015, 10:10
Given that it says G/A N1/EPR I think this is down to the old -200 that Air One used to fly.

(Probably) no autothrust... EPR manually calculated for T/O and G/A EPR probably written down in case of engine failure - You had a figure to advance to!

mr.crocodile
23rd Mar 2015, 18:39
Hi, I was following the discussion. I included the example about Airone 737 only for the reason that even there it was necessary to fill in data about normal, reduced and go-around values and I was interested in understanding why the go-around value is needed and secondly how to find that value from FMC calculations. But I'm interested in knowing that about the 737-800 NG (Ryanair planes).

Thanks

iome
23rd Mar 2015, 19:11
GoAround N1 - maximum 26k N1 value
N1 Ⓕ - maximum rated N1 value (26k,24k,22k)
N1 Ⓡ - assumed temp N1 value

mr.crocodile
23rd Mar 2015, 21:15
Perfectly clear. Many thanks...

dampierre777
12th Feb 2024, 08:34
Perfectly clear. Many thanks...
Perfectly clear...!!!
For me he didn't answer the question...why go around N1 needed for departure....?And where to find this value in FMC...?

4Screwaircrew
13th Feb 2024, 08:19
Max 26K value, you can note that from the FMC before you introduce a lower engine thrust selection and before you select an assumed temperature.

BraceBrace
13th Feb 2024, 09:50
Perfectly clear...!!!
For me he didn't answer the question...why go around N1 needed for departure....?

Not a Ryanair pilot, but the FCTM explains clearly derates are considered a takeoff limitation UNLESS conditions are encountered where additional thrust is needed on both engines (ie windshear), or after V1, increased acceleration is needed to complete the takeoff.

I would suggest to read the FCTM at least once.