AIR MODE bug found

[Guest bruchpilot]

Hello,I think I've found a small bug (easy to fix):If you are using the APU to power the busses instead of the IDGs the system switches automatically back to the right configuration as soon as the gear lifts up from the ground. So far so good and it is really nice that this AIR MODE is modelled! My compliments to the developers!However the same thing is supposed to happen as soon as you apply thrust (74% N2 for GE engine, 73% N2 for PW engine, 67% N3 for RR engine)Also the Runway Turnoff Light should go out in AIR MODE.I hope you fix this bug with the next patch.GreetingsEd

[Qavion 19]

"However the same thing is supposed to happen as soon as you apply thrust (74% N2 for GE engine, 73% N2 for PW engine, 67% N3 for RR engine)"Are you sure?I was told the AVAIL lights go out on the APU switches with the thrust on 3(?) engines at these values, but the APU generators are still selectable. Only in the real air mode does APU become unselectable.Also, I believe there is an option where if all engine generators fail in flight, you can select APU power (assuming it is already running however)."Also the Runway Turnoff Light should go out in AIR MODE."Correct. I'm surprised you didn't mention that the inboard landing lights don't dim with the gear up... and all the landing lights aren't ever-so-softly illuminated in the air with the switches OFF, and... (need I go on).Should PMDG be chastised for such mind-numbing trivia? I think not.Cheers.Q>

[Guest bruchpilot]

>I was told the AVAIL lights go out on the APU switches with>the thrust on 3(?) engines at these values, but the APU>generators are still selectable. Only in the real air mode>does APU become unselectable.Interesting. I've got my information fromhttp://carlten.tripod.com/aircraft_electri...ash400elec.htmlI think that guy designed the electrical system of the 747 so I have to believe it :-)"If the airplane is taxied with the electrical system powered from only the APU generators, advancing three or more throttles causes the system to switch to the AIR MODE. This results in an immediate load shed of all utility buses and galley buses. To prevent this load shedding, the airplane should remain on IDG electrical power until completing taxi. Load shed is designed to protect the IDG's from overload by automatically shedding these loads whenever the airplane is in the AIR MODE and there are less than two IDG's powering the system. AIR MODE is sensed either by the weight on wheels sensors or whenever three or more engines are above airmode speed (74% N2 for GE engine, 73% N2 for PW engine, or 67% N3 for RR engine). This feature also alerts the crew if takeoff is attempted with the electrical system powered from the APU generators."and"The system automatically sheds the utility and galley buses in the air whenever there are less than two IDG's powering the buses. This affects maintenance when jacking the airplane because the system would sense AIR MODE and unnecessarily shed the utility and galley buses. This has been modified in the -7 BCU so that AIR MODE load shed will not occur if the airplane is powered from external power. Load shed will still occur if the airplane is being powered from the APU generators. This is so that an attempt to inadvertently take off using APU generators only (i.e. without the IDG's powering the buses) would be readily detectable. AIR MODE is detected whenever the weight-on-wheels sensors are off the ground or engine speed on three or more engines is above approximately 74% N2 (67% N3 for RR engine)."I found it when looking for load shed aspects, discussed in another thread.>Correct. I'm surprised you didn't mention that the inboard>landing lights don't dim with the gear up... and all the>landing lights aren't ever-so-softly illuminated in the air>with the switches OFF, and... (need I go on).I don't care much for such things but did not want to omit that aspect.Never said that the PMDG isn't absolutely fabulous. But if there's any chance to patch it...GreetingsEd

[Qavion 19]

"I don't care much for such things but did not want to omit that aspect."Just because the sim doesn't have these features... it doesn't mean they weren't considered. With all projects, there are priorities... and considerations have to be made on what data and time is available to the team. In 10 years of flying 744 simulators, this i the first time I've heard anyone complain about this aspect of the 744 electrical system... "This article is of historical interest only, since the problems described here have long since been fixed.....Twenty of these (Twenty four), and many other characteristics, were corrected by the Service Bulletin and on follow-on deliveries. "So which of these problems have been fixed.. and how does the aircraft behave now? ;) (Edit: Also add to the mix, the numerous airline options regarding the electrical system, some of which were discussed during beta testing). In the end, only two types of electrical system can be modelled for PMDG (pax and freighter). There are variations from real airline to real airline and within fleets, too. At the end of the day, it's not worth worrying about... This applies to multi-million dollar sims as well. Pilots and engineers are told about the variations and they move on.. they don't ask that the sim be modified to show all the variations.Cheers.Q>

[Guest bruchpilot]

>I was told the AVAIL lights go out on the APU switches with>the thrust on 3(?) engines at these values, but the APU>generators are still selectable. Only in the real air mode>does APU become unselectable.Indeed very interesting! That is modelled in the Sim. Even with different values for P&W/GE and RR. Amazing product!GreetingsEd