Hi Gents,Some twin-engine piston airplanes have two vacuum pumps (one in each engine) i.e: default FS9 Douglas DC-3 and Beech Baron.Others have only one pump linked to engine #1 i.e.: De Havilland DH-88 Comet (FS9 default) and the superb Milton's Shupe Beech D18S.Can anybody explain me how to do for have the second vacuum pump in the system?Thanks in advance for any suggestion.Dirk Trotteyn (SANT)

Looking at the beech baron cab file, instrument air gauge uses only(A:Suction pressure, inHg) As does the Comet and the DC3. They seems to take it from the whole system. I have not come across any entry for vacume in the ac.cfg for anything other than the gauge type. My question is how is it you know there are two in the baron and comet as they only have one system wide vacume gauge?CheersShad

Dirk There is no 'engine map' entry in the 'aircraft.cfg' file for vacuum pumps. Instead there is an entry in the *.air file section 1512 'Engine/Vacuum Bit Map=3' The number 3 {11 in binary } is equivalent to an engine map entry in the cfg file for hydraulic pumps.Thus Four engines with pumps, binary = 1111 and number is 15.Pumps on engines 1 and 3 of a four eng. a/c is binary = 1010 and number 10.See attached snapshot of the DC3 air file entry.Regards Ted

Hi Shad,Thanks for your fast response.Having the two engines running stop one of them and look at the suction gauge.When stop the engine #1 in the De Haviland Comet and Milton

Hi Ted,Thanks for fast response.Your suggestion is pointing the right way!Will do some adjusts to the .air file and comment

Hi Ted,Yes, as you indicated the;1512 Vacuum System - - - *Engine/Vacuum Bit Map=3 - - - - - - in the .air file make working engine #1 and #2 vacuum pumps!Thanks again for the good help.:-beerchugCheers.Dirk Trotteyn (SANT)