PDA

View Full Version : EPR setting -- do you program it into the FMC


shon7
30th May 2006, 17:19
Stupid question but -- with regards to EPR settings -- are these programmed into the FMC or would you just not exceed say 90% of N1?

extreme P
30th May 2006, 18:17
Through the TMSP.

AUTOTHROTTLE MODES
To allow autothrottle engagement, the A/T switch must be at ARM. The autothrottle can be engaged either by manual selection of the EPR or SPEED switchlights, or automatically through selection of certain pitch modes.

When engaged manually two autothrottle modes are available, EPR and SPD.

When EPR mode is engaged the autothrottle will open the thrust levers to the maximum limit currently selected on the Thrust Mode Select Panel. EPR mode cannot be engaged on the ground unless TO is indicated on the Thrust Mode Select Panel. At 80 knots on take-off the autothrottle enters an unpowered condition known as Throttle Hold (THR HOLD annunciated) to guard against auto throttle runaway. It remains in this mode untila different thrust limit (other than TO) is selected.

When SPD mode is engaged, the autothrottle will attempt to control aircraft speed to the value selected in the speed window. The maximum power available in the SPD mode is determined by the current selection on the Thrust Mode Select Panel.

Automatic engagement of the autothrottle is discussed under the related pitch modes.

mutt
30th May 2006, 18:33
Extreme P

It would be helpful if you named the aircraft you are talking about.

Shon7
You must remember that thrust isnt a constant, it will vary with thrust rating, temperature and pressure altitude, you cant therefore just say dont exceed 90% N1.

Some aircraft, (Classic 747) have a human interface called the Flight Engineer, his/her task is to calculate a charted EPR value and set it manually in the EPR Limit computer. Other aircraft (777/MD11/744), the crew enter specific data into the FMC, that in turn displays the required thrust requirement.


Mutt

extreme P
30th May 2006, 18:51
Agreed, B757.

18-Wheeler
31st May 2006, 03:23
Some aircraft, (Classic 747) have a human interface called the Flight Engineer, his/her task is to calculate a charted EPR value and set it manually in the EPR Limit computer.


The F/E - By far the best piece of equipment ever fitted to an aeroplane, ever.