Tank to eng question

[Fergus 4]

Just out of curiosity, what is the target fuel weight in pounds that FS2Crew looks for when it triggers the co-pilot to carry out the tank to engine fuel pump config ?RegardsFergus

[byork 2,258]

Hello Fergus,I'd have to go digging through the code to find the exact value.Are you having a problem with the FO setting the fuel pumps?-Bryan

[nillefix 0]

My FO sets the fuel pumps about 1 out of 5 times.

[Fergus 4]

Hello BrianIm finding that the FO is going "tank to eng" too early. I saw himcarry out the procedure when the fuel weight was 120,000 lbs, which caused a fuel pump configwarning to be displayed on the eicas. At 120,000 lbs there is still thousands of pounds more fuel left in the inner wing tanks than the outer wing tanks. The outer wing tanks hold 28,200 lbs of fuel, therefore, for all the wing tanks to be equally loaded, the total fuel weight should be 112,800 lbs. As I understand it, the "Tank to Engine" switching is not supposed to be carried out until all the wing tanks hold the same amount of fuel, ie 112,800 lbs. I am also finding that the FO is shutting off the center tank pumps when there is still 4,000 lbs of fuel remaining there, instead of the 2,000 lbs that triggers the eicas reminder message.- Fergus

[byork 2,258]

Hi Fergus,Are you letting the PMDG 747 self-configure the pumps for you?When you select a fuel load via the PMDG menu, the pumps will self-configure.A necessary condition for the FS2Crew FO to be able to properly set the pumps is that they be properly configured before hand (self-configure ensures no errors).Pls advise.Also pls do a search using the term 'fuel' in this forum. There are other threads on this same topic which might interest you.Cheers,Bryan

[Fergus 4]

Hello BryanYes, I am using the PMDG fueling system and letting it automatically configure the fuel pumps.I have done the research you suggested but unfortunately I can't see anything that would help.I'll try loading the 747 with various fuel loads and check whether there's any variation in how the pmdg fueling system spreads the fuel load amoungst the tanks. I've already discovered that if you load an amount of fuel using the pmdg system, then go back in and change it to a slightly lower amount, the pmdg system will take some of the fuel from the outer wing tanks rather than the center tank for example. This is how on one flight I seemed to have been loaded 28,200 lbs of fuel in the outer wing tanks and also an almost full center fuel tank. I now know that the outer wing tanks actually can take 30,000 lbs of fuel when fully loaded. - Fergus

[byork 2,258]

Hi Fergus,I suggest not trying to individually modify the fuel in the PMDG 747's tanks. According to RSR, that can confuse the PMDG's fuel logic.What happens when you run the tutorial flight?Are you by chance using Sim Rates greater than 1X?-Bryan

[Fergus 4]

>Hi Fergus,>>I suggest not trying to individually modify the fuel in the>PMDG 747's tanks. According to RSR, that can confuse the>PMDG's fuel logic.>>What happens when you run the tutorial flight?>>Are you by chance using Sim Rates greater than 1X?>>-Bryan>Hi BryanI did a search on the PMDG forum and found the answer (see attached)http://forums.avsim.net/dcboard.php?az=sho...ing_type=searchIt had been noticed before that the PMDG 747 starts using a small amount of fuel from the outer wing tanks when the fuel level in the center tank is running low.As the fuel level in the outer wing tanks is slightly lower than the 30,000 lbs (full), the inner wing tanks' fuel level must therefore burn off to a lower level than expected to match the outer tanks and trigger "the Tank to Engine reminder on the Eicas". FS2CREW is doing "the Tank to Engine" switching at 120,000 lbs which normally would be right, but due to the lower fuel level in the outer wing tanks, this causes a fuel pump config warning on the Eicas.As the FS2Crew tutorial flight didn't use the center tank, the phenomenon wasn't seen.I don't use accelerated time.- Fergus

[byork 2,258]

Hello Fergus,FS2Crew can read the total fuel quantity only. The data for fuel quantities in each tank, pressure in the fuel manifold, CWT pumps' output pressure, the position of engine boost pump check valves (as per the situation described in the thread you mentioned)... that kind of data simply isn't available in the absence of a dedicated SDK from PMDG.FS2Crew does the best it can with what data is available. If you run into a situation where the FO incorrectly sets a pump, etc., by all means go ahead and manually re-configure the pump.Cheers,Bryan

[Fergus 4]

Hello BryanI love flying with the FS2CREW programs. I have both the PMDG 747 and Lvl-D 767 editions and very rarely fly anything else nowadays.I understand the limitations due to the lack of a PMDG SDK and I didn't mean to appear to be being critical of your program, which as I say I now find invaluable.Now that I understand why the aircraft's fuel system isn't behaving as I and FS2CREW expected, I feel I can enjoy using both the aircraft and FS2CREW much more.Thanks for taking the trouble to help me.I look forward to flying the a320's with a co-pilot soon.- Fergus

[byork 2,258]

Hi Fergus,Not a problem. The A320 is looking good :-)Cheers, Bryan