MstrCmdr Posted June 3, 2018 Posted June 3, 2018 When starting the hornet, right engine first, I set up all my AC-powered controls and start alignment. When I go to start the left engine it resets my AMPCD and left DDI once the gen kicks on. I did an air test and found that the generator switches do not work correctly. Disengaging the right GEN turns off the right DDI, disengaging the left GEN turns off the left DDI and AMPCD. I've adjusted my startup procedures to start both engines before engaging and AC-powered items. Anyone else have this issue?
Rainmaker Posted June 3, 2018 Posted June 3, 2018 When starting the hornet, right engine first, I set up all my AC-powered controls and start alignment. When I go to start the left engine it resets my AMPCD and left DDI once the gen kicks on. I did an air test and found that the generator switches do not work correctly. Disengaging the right GEN turns off the right DDI, disengaging the left GEN turns off the left DDI and AMPCD. I've adjusted my startup procedures to start both engines before engaging and AC-powered items. Anyone else have this issue? The dual gen systems are designed to run in parallel of one other with cross tie fuses/contactors allowing you to operate the other system should you have a single gen failure. What you are seeing is a power cycle as the system swotches over. It wouldn’t be a bug unless they have the wrong systems tied to the wrong electrical buses but the power cycle itself is perfectly normal IRL depending on how the systems are laid out. Saying it doesn’t work correctly is probably not true. The one bug I possibly see is the power cycle not happening as the gens are brought back online, the system resets only happen when turning a gen off, not back on. Even still they happen in the real jet, all depends on how quickly the changover happens.
MstrCmdr Posted June 3, 2018 Author Posted June 3, 2018 So this is correct? Let me just clarify. The left DDI and AMPCD screens are supposed to reboot when the left engine gets up to speed? I just assumed an issue since I did not see the same instance in Redkite's, Crash's, Wags', or the Reapers' vids on startup tutorial. I'm not being an ***hole-Were you involved with the Hornet IRL? You seem to have much knowledge.
Rainmaker Posted June 3, 2018 Posted June 3, 2018 So this is correct? Let me just clarify. The left DDI and AMPCD screens are supposed to reboot when the left engine gets up to speed? I just assumed an issue since I did not see the same instance in Redkite's, Crash's, Wags', or the Reapers' vids on startup tutorial. I'm not being an ***hole-Were you involved with the Hornet IRL? You seem to have much knowledge. I have experienced the same. Is it correct? I am not surprised to see it do so so I would not be surprised if it was. I am not involved with the hornet no. I do have an electrician background and familiar with dual generator systems. I don’t know why they may differ from everyone on other videos no. I have nothing to offer there. I am just responding to say that the cycling of power to the avionics systems is not uncommmon when the system is designed like it is.
MstrCmdr Posted June 3, 2018 Author Posted June 3, 2018 (edited) Ah nice. Well I'm thinking it may have something to do with the INS knob. I'm going to try and test different startup settings. I put the knob into alignment before the left engine starts - I'll try not. Confirmed. If you initiate INS Alignment before starting both engines (right first then left) the left DDI and AMPCD will reset. Edited June 3, 2018 by Mstr&Cmdr
uunilenkki Posted June 3, 2018 Posted June 3, 2018 The DDIs etc rebooting after L engine starts is not normal in real ones. You should be able to feed for example the AC bus 1 (left gen out) by using GEN TIE switch. Then you should have power for turned off DDI and/or MPCD.
Rainmaker Posted June 3, 2018 Posted June 3, 2018 So which buses should primarily operate the displays? Left side or right side? If left, I could see them cycling as the left gen takes over primary buses when it comes online. If it’s normally powered by right side buses, I would think the displays should maintain constant power as it would still be powered by the right gen. Same would go for INS, would depend on what is supposed to be primary power source. Someone has labeled the thread “not a bug” so I assume someone has that answer already. With a schematic, I could probably give you a good guess but I don’t have that info.
uunilenkki Posted June 3, 2018 Posted June 3, 2018 If I remember right the startup procedure, the ac buses 1&2 are connected via bus tie relay (so both DDIs work with only R/L engine on). And if which ever gen goes off the GEN TIE relay can connect the buses, because bus tie is disconnected if there is some major fault behind bus 1 or 2. GEN1 (left) for LDDI, MPCD GEN2 ® RDDI, that sounds logical, not 100% sure
Rainmaker Posted June 4, 2018 Posted June 4, 2018 If I remember right the startup procedure, the ac buses 1&2 are connected via bus tie relay (so both DDIs work with only R/L engine on). And if which ever gen goes off the GEN TIE relay can connect the buses, because bus tie is disconnected if there is some major fault behind bus 1 or 2. GEN1 (left) for LDDI, MPCD GEN2 ® RDDI, that sounds logical, not 100% sure That sounds like it matches the way the cureently have it modeled then...to me anyway.
uunilenkki Posted June 4, 2018 Posted June 4, 2018 (edited) I checked the principles and I was a little bit inaccurate. In startup the parking brake must be on to trigger the bus tie contactors to connect both AC buses, and every system can be powered when first engine is started. When the second gen comes online, both generators feed their own bus through power contactors R&L, bus tie contactors (R/L) are still closed so both gens can provide power to both buses if one gen is put offline for some reason. So if you shut down for example left engine or use L gen switch there should be no lack of power to the AC bus L, therefore none ofthe DDIs or MPCD should go off. But if you have pbrake off and cycle both gens at same time (power off), the bus tie logic is resetted and generators feed their own bus only when online again. The OPs case could happen if starting the engines without parking brake on. Edited June 4, 2018 by uunilenkki
Rainmaker Posted June 4, 2018 Posted June 4, 2018 (edited) At least for me, as of now, they will cycle and reset and there is just a momentary loss in power. I assume this is just simulating the contactors cycling once the applicable gen is off to reroute power from opposite gen to power those buses. The -15 works this way so everything seems fairly normal to me. Odd to me that anything is tied directly to brake handle. Wonder why they designed that? Edited June 4, 2018 by Rainmaker
uunilenkki Posted June 4, 2018 Posted June 4, 2018 Yeah, I can't recall the explanation to the parking brake-bus tie connection, a little bit weird it is though.
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