DS and family were on board on 10.2 to CPT having turned back over Montluçon due to 'navigation instrument problems'. Spent till 22H45 at CDG before departing on F-HRBF with new crew. Pity there wasn't a possibility of testing this a/c in the meantime.. but better to turn back and be safe than sorry. AF may well be out of pocket after paying all their EU261 claims ...