If a helicopter's tail rotor fails, is it possible to perform an emergency landing?
Although I used to think this was impossible, I now believe this can be done using weathervaning.

At a fast enough forward speed, the airflow will naturally keep the helicopter facing in that direction. For an example of someone doing this in reality, for an almost identical time period that OP requested, see this link:

http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&amp;objectid=10493099

According to the link, he needed to maintain 80 knots forward speed to prevent it from rotating out of control. Note whether this is possible may well depend on the weathervaning charactistics of the particular helicopter.