I have exactly the same issue , i spent 2 days getting all the parts and fixing it up but no matter what angle i look at the uh1 i get no option to fix the tail rotor, we have tried fuel tank parts engine parts scrap and even wheels but we never get the option to repair the ATHR (tail rotor). Then the servers were updated to 1.5.3 and all our repairs reset and the thing us broken uttely again , but we tried all the same , still no option to repair the tail ... anyone able to confirm how this is done , or if its broken ?