Hello All, I don't know if this has already been discussed but I seem to have observed something little bit off with the duct pressure gauge. I was on the ground at KBOS with the 737-800W (United post-merger, EFIS/Map style cockpit) preparing for a flight to KCLE. I had started up the APU, opened the APU bleed valve, packs were on AUTO, and I ensured the engine bleed valves were off. The packs were on at the time and the Duct Press was indicating ~20 PSI. The ground equipment was all disconnected. The weirdness started just before I pushed back. As I switched the packs off in preparation for engine start, the Duct Press dropped to about 10 PSI. Shouldn't this be the other way around? Shouldn't turning the packs off INCREASE the duct pressure in order to accomplish APU bleed start? Am I doing something procedurally incorrect? I'm sure if I had been doing something wrong, the engines would not have started. I was still able to accomplish a normal engine start on APU air even though the Duct Press read about 10PSI when I opened the No 2 start valve (Selected eng 2 to GRND). I did not see an appreciable decrease in duct pressure after selecting no 2 to GRND. Thanks for any help,Adam

Has anyone elsenoticed this?? I don't have the opportunity to try and reproduce it at this time as I am supposed to be workiing, but I will try later this evening. Adam EDIT: PLEASE DISREGARD. I found my answer with my little friend the "Search" button. And the answer is that PMDG is brilliant for modelling the APU saving fuel by regulating load. I swear this thing is alive! I thought I tried searching for that last night before posting...I must not have. Thanks.