3DR Y6 DIY RTL malfunction?

RTL has worked fine for 10-15 flights. Tonight I performed compassmot test; 6% & 7%

Did a test flight in back yard, alt-h drifted to back about 100 ft, switched RTL, all seemed well until it began its descent, then did slow toilet bowl down and “gently” crashed only breaking a prop.

What happened? I’m not too confident now to put it back up in the air.

Thanks for help.

P.S. I just noticed one of the nuts were off on the tail holding the FC base plate down; it does flex quite easily. The tail does move a bit now as well. I Loctite all steel fasteners, but it is possible that one was missed. Could that have possibly caused enough vibration to confuse the FC and GPS/compass? See attached photo.

Hi I would be most interested to hear what went wrong because I had a similar problem yesterday afternoon - coincidence? :confused:

The GPS HDOP was at 2.1 which is quite normal for around here certain parts of the day. I tried to do an auto mission. Auto takeoff was fine and then suddenly halfway to first waypoint my Y6(B) got stuck in mid air. Auto would not continue and RTL does nothing. Tried to switch between auto and RTL several times. No response even though GPS reports 3D lock. Slight twitch when I switched to loiter and was able to fly home and land in loiter mode. The machine loiters fine. I disconnected and reconnected the batteries and did a manual takeoff. Moved some distance away from me and put into loiter. All fine then switched to RTL. Nothing happens as if still in loiter. Telemetry reports RTL mode engaged so I know that works. I did not manage to get RTL to work again before I ran out of time and batteries.

Would HDOP of 2.1 with 8 satellites and 3d lock result in no Auto or RTL function? Alt hold also worked fine btw.