737 -200,EPR settings

[3 putt]

Any info that I can get on the web regarding 737 profiles give examples for CFM powered machines and the N1 settings for such.
Now,can anyone tell me if the JT8D profiles are flown with reference to the EPR or the displayed N1?
Maybe some of you '200 drivers might give examples.
Thanks.

[LargeJet]

It's been a while........but from my old memory EPR is what was used for power setting. I seem to remember that at 250kts about 1.5 to 1.6. 210kts clean would require about 1.35 (up a bit or down a bit depending on weight). This power setting also worked quite well as you put flap out and slowed down. Rough guide for final approach EPR was the weight minus .07 for a 40 flap or minus .17 for 30 flap. e.g 45T and flap 30 EPR approx. 1.28. Also as a rough check go-around EPR was 2.08 minus the temperature on the ground. Doesn't work for all temps, can anyone remember up to what temp it worked? Hope this helps with SCUD flying!!

[john_tullamarine]

One uses EPR to set major power figures (TO, GA) and checks N1 which is what really tells the pilot about thrust.

For routine manoeuvring, it is a matter of preference. Some pilots prefer EPR, others N1. N1 is the finer setting, EPR somewhat coarser.

[flufdriver]

We set power by EPR, on the Ground you pause at 1.40EPR and approx. 4000lb of fuel flow to check for surge bleed closure, in the air about 1.35 will hold 250 knots, all engine bleed corrections are applied to EPR settings, (except for min N1 with anti Ice on). As an old 727 driver I also use fuel flow as a target for power settings , after all its the same engine. Naturally, you keep scanning the other parameters, also keep an eye on the A/C Duct pressure if parameters don't line up as they should you may have uneven engine bleeds.

[Slasher]

Large Jet its 30deg OAT.

[Gspot]

Use EPR for setting takeoff power but be sure you achieve the expected N1 value (90% plus), that is what happened to Air Florida when they crashed into the Potomac, from memory I think the p2t2 probe was iced over and that resulted in getting a good EPR reading but N1 was low because they didn't have full power, they only thought they did, sadly the crew didn't notice, the rest they say is history.

For all other flight regimes I use fuel flow, I had a BAC 1-11 sim instructor who used the rationale that 1) it is instant, no spool up time. 2)Assume that to perform a normal two engine approach you need to have a fuel flow of say 2200Lbs per engine, what you are saying is that you need the energy provided by burning 4400lbs of fuel to keep the aircraft stable in that configuration. If then you need to do a single engine approach it will still take approximately 4400lbs to fly the jet, so guess what - set the remaining engine to 4400 lph. It will not be exact but it will be ballpark and give you a place from which to start.

I don't get to fly the -200 much but the -300/-500 need approximately 2800lbs per side for 280kts, 2500 lph per side 250kts, 2100lbs for 210kts clean. That 2100 - 2200 will then yield approx 190kts with flaps5, 170kts gear down and flaps 15, 150kts flaps 25 all in level flight and vref +5 to 10 kts with flaps 30 on a 3degree glideslope. These are all of course approximate but are a good benchmark from which to start fine tuning. The -700 uses slightly less fuel so 100 lbs per hour per side less will be about right.

If you need a cruise descent ie they are trying to get you down before you want to decend on profile then set 1000ft per minute rate and reduce the fuel flows by about 1000lbs per side this will keep you at cruise Mach to changeover and then at 280 kts until reaching your normal profile.

Hope that helps. Keep the shiney side up! ;) ;)

[ 25 September 2001: Message edited by: Les Couilles de Chien ]