timmyEGCC
You are misunderstanding. APU start won't tell you to start yellow pump. When wind milling becomes less and G+Y low pressure will tell you that. FAC1 needs to be reset because before emergency gen starts A/C is supplied by only batteries for 8 seconds. That trips both FACs. FAC1 when reset is supplied by EMER GEN and recovers rudder trim although you cannot see the figures. Also characteristic speeds are available. FAC2 is not supplied even on EMER GEN.