AlexArt wrote on May 1^st, 2012 at 8:38am:

The poll is incorrect. APU generator is apparently working fine, only the engine will not run. Markoz too all the time indicates how long it all works. But never once wrote, is it possible to start the engines. I also have all the apparently works, but starting the engine is impossible. We must ask - Can you run the engines after 5-6 minutes of work APU or EP?

I agree, and I disagree. Engine start is not the problem, it is a symptom of the problem. The problem is dead battery after 5-6 minutes. That is why the engines won't start after some time.

After you start the APU, dial in a VOR or ILS so the HSI will go active, then watch in about 6 minutes the HSI (all avionics actually) will lose power. If you then shut down the APU you will see that the battery is dead. All the other systems that were still operating were running on APU generators, but it seems the avionics was possibly on battery power the whole time and never tripped to the APU gen.

The poll is correct but it could be misunderstood because the only indication of power loss is the HSI and radio and some people might think they have not lost battery power because everything else besides avionics stays running (on APU generator as it should).