"when he arrives" in Subjunctive?

Question

The sentence, "Fernando will begin complaining when he arrives".  If he always complains about everything, would it be "cuando llega"?

Accepted Answer

Hola Kaly
That may be the case, but Fernando hasn't arrived yet and this is what we refer to when we say "a future action". You normally see the use of the simple future in the main clause, as you can see in this one "Fernando will begin complaining...." indicating that it will happen. 
For this sentence to express an habitual action that does happen, we'd say:

Cuando Fernando viene siempre se queja.
When Fernando comes (everytime he comes) he always complains.

This is now seen as an action that is habitual, it to happen all the time. 
The previous sentence doesn't indicate 100% that he always complains, it indicates that when in that occasion he arrives (whenever that happens in the near future) someone knows that he will complain (maybe because Fernando has said in a previous conversation that he will do so when the time comes, but that may be his first time doing it.) 
I hope this clarified it.
Saludos