First off, thanks for a fantastic airplane and great documentation. I've been very pleased with it.I have a few questions. All minor things:1. With all engine driven and demand hydraulic pumps turned off, the elevator trim buttons on my joystick appear to adjust elevator trim normally: I see the trim indicator move, and the plane's trimmed airspeed changes. Should trim be operable with no hydraulics?2. The manual says that hydraulic system 2 feeds the right autopilot servos, and hydraulic system 3 feeds the left autopilot servos. I found this to be reversed: system 2 feeds the left, and system 3 feeds the right. Ok, that one is not a question, just an observation.3. A checklist item calls for "Ground PROX Light...... EXTINGUISHED". I can't find it. Where is it?4. Another checklist item calls for "Oxygen Pressure....... Sufficient for Flight". I can't find Oxygen pressure on the Secondary EICAS 'Stat' page. Did my airline remove the oxygen system from my plane? They'll do anything to save a buck...I'm excited to have a sim that is so detailed that nitpicky questions like these are worth asking. Good job, guys! Wayne Conrad

I'm not an expert but here's my nickels worth:1. The trim servos are probably electric.3. FO Panel (lower left)4. I recall there being a gauge on the overhead upper right.. but not very sure on this one.I agree.. best FS add-on.

"1. With all engine driven and demand hydraulic pumps turned off, the elevator trim buttons on my joystick appear to adjust elevator trim normally: I see the trim indicator move, and the plane's trimmed airspeed changes. Should trim be operable with no hydraulics?"The 744 actually doesn't have elevator trim. It does have Stabiliser Trim however... and you are right, the Stab Trim shouldn't work without (#2 and #3 hydraulics. The Stab Trim is operated by electrics, but the electrics only control hydraulic valves which run the stabilizer trim motors with hydraulics. The stab trim is high demand, so any residual pressure in the hydraulic systems will disappear in seconds. I have been able to reproduce this on my computer. Attention PMDG! :("2. The manual says that hydraulic system 2 feeds the right autopilot servos, and hydraulic system 3 feeds the left autopilot servos. I found this to be reversed: system 2 feeds the left, and system 3 feeds the right. Ok, that one is not a question, just an observation."I couldn't fault this on my computer. I engaged the autopilot, then disabled the applicable hydraulics... The autopilot disengaged after a few seconds. How did you test this?"4. Another checklist item calls for "Oxygen Pressure....... Sufficient for Flight". I can't find Oxygen pressure on the Secondary EICAS 'Stat' page. Did my airline remove the oxygen system from my plane? They'll do anything to save a buck..."As far as I recall, the PMDG O2 indications were not modelled (nil time to model them prior to release)Cheers.Q>

FS2Crew allows you to do a Oxygen test, but yeah never found anyway in the default AC

Speaking of Oxygen tests, here's an old FS2Crew "real-world versus sim world" video I created which you might find interesting...http://66.135.39.111/fs2crew/FS2Crew_747_Preview1.zipCheers,Bryan

>Speaking of Oxygen tests, here's an old FS2Crew "real-world>versus sim world" video I created which you might find>interesting...>>http://66.135.39.111/fs2crew/FS2Crew_747_Preview1.zip>>Cheers,>Bryan>Interesting, thanks for posting that.Jay

Thanks, everyone. I'm glad I'm not nuts about the stabilizer trim.To test which autopilot used which hydraulic system, I shut off all hydraulics, then enabled just one system, and saw which autpilot would engage. Not much different than how Qavian did it. It could be that I remembered it wrong and the manual is right. I'll try it again.I found the ground prox warning light. It's the leftmost button of the ground prox control panel. It lights up when it's issuing a warning.

"To test which autopilot used which hydraulic system, I shut off all hydraulics, then enabled just one system, and saw which autpilot would engage. Not much different than how Qavian did it "Not so sure. Having 1 out of 4 hydraulic systems disabled is different from 3 out of 4. The A/P also relies on the operation of the Stab Trim. If both #2 and #3 Hydraulic systems are disabled, you have no Stab Trim.I also have to refresh my memory on the operation of the aileron/spoiler drive system. The roll control "power assist" mechanisms in the wheel wells, known as the CLCP's, need certain hydraulic systems to be powered to provide normal operation. There are 2 CLCP's (for left and right aileron operation). However, mechanical backdrive linkages in the aileron system may provide both proper autopilot operation and aileron ops with just a single hydraulic system running.NOTE: With some of the control surfaces not working with the lack of 3 out of 4 hydraulics (in your scenario), the A/P may have to provide a lot more input to give the same output (to steer the aircraft). Cheers.Q>

I just duplicated the test results. This time I tried it both ways: Starting with all hydraulics off, enable one hydraulic system, and see which a/p will engage; and starting with all hydraulics on, disable one and see which a/p will no longer engage.My test results:Hyd sys 1: Center a/pHyd sys 2: Left a/pHyd sys 3: Right a/pThe systems manual (p. 53) says,Hyd sys 1: Center a/pHyd sys 2: Right a/pHyd sys 3: Left a/pThis is with the download version of the pax plane.Not trying to sound like a lawyer... this isn't a case I'm trying to win. Just a plane to decypher and a mystery to understand. I like pushing all of the pretty buttons. Does it show?

I was testing mine using the Cargo version. Not sure why the two PMDG versions are different. Has anyone else tested this?ThanksCheers.Q>

>Not so sure. Having 1 out of 4 hydraulic systems disabled is>different from 3 out of 4. The A/P also relies on the>operation of the Stab Trim. If both #2 and #3 Hydraulic>systems are disabled, you have no Stab Trim.>My Stab trim is working with #2 and #3 hydraulic systems disabled. Also works with #1 #2 #3 & #4 systems disabled.