19991228044589A

(-23)During a sightseeing flight, and while manuevering low level at approx. 250 feet AGL and 60 mph, as the pilot was increasing collective pitch to level off from a gradual descent, the low rotor RPM waring horn sounded. The pilot verified that the rotor RPM (nr) was indicating approx. 300 to 320 RPM and that the fuel control lever was in the flight position detent. The pilot initiated an autorotaion and landed on roughdown sloping terrain. After the a/c touched down it skidded into a ravine, impacted a tree, and rolled over. A post accident inspection of the a/c engine revealed a loose pneumatic line connector at the surge accumulator between the fuel control and the govenor. (.4) history of flight: on December 28, 1999, about 1050 hours pacific standard time, an aerospatiale AS-350D helicopter, N3593S, collided with terrain following a loss of engine power while maneuvering at low level on a sight-seeing flight over the interior of santa catalina island, Avalon, California. Island express helicopters, inc., was operating the helicopter under the provisions of 14 CFR part 91 as a for-hire sightseeing flight. The airli NE transport pilot and five passengers sustained minor injuries; one passenger sustained serious injuries. The helicopter was destroyed. The local flight departed a helipad near Avalon harbor about 1030. Visual meteorological conditions prevailed and a company flight plan had been filed. The accident site coordinates were 33 degrees 24.98 minutes north latitude 118 degrees 27.924 minutes west longitude. The pilot supplied a written statement, and the operator's federal aviation administration (FAA) principle operations inspector (poi) also interviewed him. The pilot stated that he picked up passengers from a cruise ship at pebbly beach for a 30-minute flight over the island. Approximately 20 minutes into the flight, the pilot proceeded inland from the two harbors area. As the helicopter passed over a ridgeline, the pilot spotted a herd of buffalo in a valley near some dried up watering ponds. He began a descending and decelerating right turn and crossed the ridgeline approximately 250 feet above ground level (AGL) at 60 to 70 mph. About midway down the ridge, the pilot and passengers heard the low rotor RPM warning horn. The pilot lowered collective and the horn stayed on. He notedthe rotor speed was down between 300 and 320 RPM. He confirmed that the fuel flow control lever was down in the detent in the on (flight) position. The pilot concluded that he would have to make an immediate landing. As the helicopter descended into the terrain, he applied collective and flared to cushion the landing. He stated that the helicopter landed downslope at an estimated 10 to 15 mph, and the tail rotor struck the ground first. The helicopter pitched forward and the nose struck the ground. The helicopter continued to slide down the hill, collided with trees, and rolled onto its right side. The passengers in the dual seat to the left of the pilot were now dangling above him. Everyone except a young male passenger in the back right rear seat was able to exit the helicopter. The young man's leg was pinned under the wreckage. It took approximately 30 minutes to facilitate his exit from the wreckage. The passengers reported that just after they heard the horn sound, they felt the helicopter shake and the pilot report that they were going down. One passenger reported that the float mechanism detached uphill from the accident site, and he dragged it back to the wreckage to help identify their location. When the helicopter did not return at the scheduled time, the operator notified local authorities and a search was initiated. The accident site was located about 1 hour 20 minutes after the accident.