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Guest Ron Freimuth

EPR gauge?

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Can anyone shed more light on the EPR guage?I know that EPR stands for engine pressure ratio, and is a measure of the ratio between the engine's inlet and exhaust nozzles, and is one means of depicting the thrust the engine is developing.Any real jet pilots out there know if the indications for the EPR gauge seem realistic for the FS2002 jets?On the ground in a IFDG 757-200 I see 1.00 EPR with the engines off (expected), and EPRs > 1 when setting takeoff thrust (also expected). As I climb to altitude, however, I notice the gauge behave in a way I don't expect, falling back below 1. During a recent transoceanic flight, at FL390, the gauge read 0.45 when at 90% N1, and about 4900/lbs/hr/side fuel-flow, for 0.80 mach cruise (numbers from memory and may be slightly off).Is it not true that seeing EPR gauge indications less than one would mean pressure is greater at the inlet of the engine than the exhaust (i.e. airflow reversed)?How does a pilot normally interpret the EPR gauge, and is the EPR gauge used in other phases of flight besides takeoff?--Andrew, KGFK

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You are absolutely correct. Looks like you have a faulty EPR gauge.EPR is the ratio of exhaust pressure (Pt7) and inlet pressure (Pt2).= Pt7/Pt2So if you should read an EPR of less than 1.00, you either could have a blocked or disconncted Pt7 sense line, or a malfunctioning EPR computer.(if your engine is otherwise operating normally) On the other hand one could get a high EPR reading if the Pt2 line is blocked (by an insect or ice etc.)This is why it is so important to crosscheck EPR with N1 during take-off.(See Air Florida B737 crash in Washington D.C. many years ago)EPR values are different for each engine type. Usually high bypass engines will have a lower range of EPR (sometimes even below 2.00 for take-off thrust)than older low by-pass engines.During climb EPR will usually be below take-off values (but definitely above 1.00).Charts (or the FMS) give the crew the required EPR settings for each phase of flight.Hope this helps.

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Wonderful! Thanks for the sanity-check.The indications were seen on an IFDG 757-200 modeled with the Rolls Royce RB211-535E4B engines. I was using a modified 777 panel. I'll have to take a spin in the default 777-300, and see if there is a bug in Microsoft's gauge programming. Using their panel with their jet model, if I don't see EPR >1, then "somebody's got some 'splaning to do!"Thanks again,--Andrew, KGFK

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>The indications were seen on an IFDG 757-200 modeled with >the Rolls Royce RB211-535E4B engines. I was using a modified >777 panel. I'll have to take a spin in the default 777-300, >and see if there is a bug in Microsoft's gauge programming. >--Andrew, KGFK The FS2K and FS2K2 EPR gauge reading is poor. Almost useless. MS may have improved it a bit when this was brought up in the FS2K2 Beta testing, but don't know how to do much of anything right as far as the 'flight model' goes. Apparently they had a contractor do the code, and are mostly lost when it comes to fixing anything. I'll try to get EPR correctly programmed in a gauge for the DF B727 before it comes out. N1 and N2 are good, but EPR is the main turbine power indicator for this AC.-RAF

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