FSD beyound safety limits is normal message in that situation, keep in on neutron star's "shower" and it will load up. My technigue: ok now you are in neutron system, seek those "showers" and fly to one of them at shallow angle away from star itself. Light throttle. As soon as you are in, and FSD beyound safety limits warning sounds, throttle to zero and enjoy the ride, try to keep yourself in the "shower", as soon as its says FSD supercharged, throttle to max, 90 degrees turn and get out from "shower".