We were about twenty miles from the Oregon/California border when we started hearing this loud and constant sound. It sounded as if someone was tapping a large stick against the RV roof. We pulled over and, when Aaron climbed the roof to investigate, found out that the tapping noise was a result of the roof covering that somehow had gotten torn, and the torn flaps were hitting itself against the RV. With no discerning solution in mind, Aaron attached pieces of duct tape for a temporary solution. The tapping noise is now gone, but in its place the RV sometimes makes this farting sound as the air passes through the pieces of duct tape.