Can the APU generator power weapon system or autopilot?

[bolek]

I cannot get it to work. If I turn off the two main generators, no matter what I try the autopilot and weapons systems do not get power. But from the manual it seems like it should be possible for the APU generator to power them for a limited time?

 

Can someone confirm if this is possible and it if so how? Or not possible :-)

 

Thanks

[aileron]

I think the problem is that Gen 1 & 2 on the AC Panel are for 115 and 36 volt AC systems on an AC Bus.

 

The rectifiers on the DC Panel convert the AC to DC for the DC bus I imagine.

 

So since the Standby Gen from the APU is a DC system on the DC panel. Did you activate it?

 

Maybe that will help you.

 

ETA: Also you might have to put the AC 115 and 36 systems back on the bat bus or MANual.

 

Also its probably a bad idea to run Standby Gen and Rectifiers at the same time. I imagine in the real world this would overload the system.

 

Edited October 25, 2017 by aileron

[bolek]

Thanks, but still doesn't work. I have Standby Generator on, rectifiers off and 115/36 AC manual, as in the attached picture.

 

BTW, rectifiers don't seem to affect APU Gen Load meter.

[Chic]

Try activating the Equipment Test switch to link the APU standby generator to the Rectifier Buss.

 

 

The AP is on Essential Buss, not sure bout Weapons system.

Edited October 27, 2017 by Chic

[bolek]

Thanks, so with the Test Equipment switch on (in addition to the previous settings) weapons work (well, at least some of them)!

 

But autopilot only works partially. Only altitude channel can be engaged (which it couldn't before). But heading and bank/pitch channels still don't work.

 

OTOH, fans now spin too :-)

[Chic]

Thanks, so with the Test Equipment switch on (in addition to the previous settings) weapons work (well, at least some of them)!

 

But autopilot only works partially. Only altitude channel can be engaged (which it couldn't before). But heading and bank/pitch channels still don't work.

 

OTOH, fans now spin too :-)

 

 

Gyros and Attitude indicators on??

At least you'll stay cool.

[bolek]

Attitude Indicator is on but the Gyro Compass is not. Garmin GPS works.

 

So the main issue is really the pitch/bank stabilizer.

[kuki767]

Haven't flown in a Mi-8 for a while, so most of this is from memory. :D

 

Engine generators generate 3-phase 204V AC, that is also:

-transformed to 115V AC single phase (in case of both eng gen failure, the PO-500A inverter is used to power essential equipment)

-transformed to 36V AC 3-phase (in case of both eng gen failure, the PT-200Ts inverter is used to power essential equipment)

-transformed to 36V AC single phase (controlled by instrument inverter switch)

-rectified to 27V DC

 

Stand by generator (from APU) generates 27V DC that can be connected only to the battery bus.

By using equipment test switch, you're connecting the APU to the rectifier bus, and this is used for equipment testing (:)), but can be also used in flight for emergency situations to power flight essential equipment

 

AFAIR, the pitch and bank channel of the autopilot system is using attitude data from the co-pilot's attitude indicator, which isn't connected to the essential bus and that's why it could not be turned on. If you had requested external power, you would be able to.

 

Yes, the eight has a slightly complex electrical system :joystick:

 

AlphaOneSix, feel free to correct any misinformation. :D

[AlphaOneSix]

Deleted incorrect info

Edited November 1, 2017 by AlphaOneSix

[bolek]

Should the rectifiers be on or off?

[AlphaOneSix]

Deleted incorrect info

Edited November 1, 2017 by AlphaOneSix

[bolek]

Thanks, right, that's what I was asking.

 

Hower, even with 36V inverter set to manual, the co-pilot attitude indicator (and autopilot pitch/bank) still doesn't work.

[AlphaOneSix]

Deleted incorrect info

Edited November 1, 2017 by AlphaOneSix

[bolek]

Ah, thanks. I don't think it does (there is nothing in the ground crew menu) but in a sense it doesn't matter because the point of this exercise (which perhaps I should have stated before :)) is to see if I can try complete a combat mission after both generators fail. It seems like it might be possible since weapons work and I can still fly, but quite difficult to aim without the bank/pitch stabilizer. Oh well.

 

Thanks a lot for the education.

[AlphaOneSix]

Deleted incorrect info

Edited November 1, 2017 by AlphaOneSix

[sLYFa]

Autopilot should work with just batteries as long as the hydraulics are working.

Definetely not as the AP requires 36V Gen. Bus to work.

Edited October 31, 2017 by sLYFa

[AlphaOneSix]

Deleted incorrect info

Edited November 1, 2017 by AlphaOneSix

[sLYFa]

No you can´t. You can only power the 36V PT-200C bus with batteries which does not provide power to the autopilot. For the AP to work you need power on the 36V AC Generator bus which is only powered by the generators (See Fig. 7.1 in the manual). The PT-200C and PO-500 inverters and their buses are only meant to power most critical equipment, which the AP is not part of.

Edited October 31, 2017 by sLYFa

[AlphaOneSix]

All my information in this thread is wrong, as it is not applicable to the Mi-8MTV-2.

 

The autopilot requires at least one of the two main AC generators to be operating, or AC external power.

Edited November 1, 2017 by AlphaOneSix

[Rogue Trooper]

Please AlphaOneSix leave the thread alone, it is good for us to see a linear attempt at fault finding even if its results are a negative.

Believe me this is my real life job and all attempts to rectify a problem, no matter what the result is critical information.

And it is just damn nice for the rest of us late comers to follow the line of fault finding so that if the critical moment comes to us at a point of urgence.... we need not rack our brains finding a solution and instead spend our critical time to plan our fast descent to Earth!

 

 

There is no shame in giving it a go no matter what the outcome!

Edited November 3, 2017 by Rogue Trooper