The helicopter was engaged on a cattle mustering, with several landings being made to open and close gates. On the accident flight the pilot noticed that the fuel gauge was indicating less fuel than expected, but he then became involved in mustering some troublesome cattle and the next time the gauge was checked it indicated empty. As the low fuel light had not illuminated the pilot decided to land as soon as he found a clearing, but about 30 seconds later the engine failed. The helicopter had been flying about 5 feet above the tree tops at about 20-25 knots. The pilot attempted to side-slip to the right into a slightly more open area, but was unsuccessful and made an autorotational landing into the trees, the helicopter coming to rest upright suffering substantial damage. Subsequent investigation revealed that the fuel filter bowl had been distorted, probably by a projection on the ground during one of the previous landings, allowing fuel to leak until the engine failed due to fuel exhaustion.