I have not changed a Dart prop. since the 1980's but as I recall removing the prop not in the feathered position is not a problem with the prop itself rather that the pitch lock assembly which comes off with the cylinder head has the spring in the compressed position - it will be like that until re-installed and the prop feathered hydraulically.Be aware that the cylinder head has a left hand thread as has the inner oil transfer tube - the biggest and smallest threads on the prop assembly. The danger with removing the prop unfeathered is that if there has been a failure in the pitch lock assembly it could result in the compressed spring propelling the cylinder head at high speed when removing it which could injure personnel. The situation you have now is not dangerous as the lock unit although under spring pressure is unlikely to unlock itself - even if it did there would be little risk of injury.