Sorry 212man i should re read the RFM before i start going on a long rant lol
I was wrong about SPIFR. You are correct in that you need two AP's in ATT for that. But the point i was trying to make is that the aircraft is most likely still perfectly safe to fly if your Flight Director wont couple to your AP because many things can cause this happen. Some potentially dangerous and most not life or death so much more detail of the exact fault if known is required to know if the helicopter is safe and fit for flight. I would "ASSUME" the engineers know that the fault is minor and thats why they keep returning the aricraft to service even though you cannot couple.
Brian; on the S76's its all about what operations the aircraft is being used for that dictates its AP coupling limitations.
For example on the 7600 AP's in both 412's and 76's are identical in design but obviously custumized for each aircraft. There is a jumper (or 2 i cant remember off the top of my head) placed between pins on the AP computers that tell them if they are allowed to couple with just one fully functiong AP or not. Its as simple as removing or installing this jumper to change configurations. I'm not absolutly certain on the details but i believe only SAR and EMS aircraft are allowed to fly 3Q with only one fully functional AP. The Sperry 7000 AP system is the same way which you find on older aircraft.