LAS VEGAS (KLAS) — The preliminary report has been released for a helicopter that crashed near the Red Rock Canyon Conservation Area Visitor Center last month. Two people were killed in the accident.
The report said as Robinson R44 II Raven went down when it crash on Oct. 23. The helicopter, owned by Binner Enterprises LLC, and operated by Airwork Las Vegas took off from North Las Vegas Airport at 3:35 p.m., and it crashed at 3:53 p.m.
The airline transport pilot and passenger survived the impact, but they both later died from their injuries. The reporter said the helicopter was getting maintenance before it was rented out.
The pilot asked why the helicopter was in maintenance, and the office personnel told him that an earlier flight was canceled because that pilot had found sediment in the fuel tanks. The accident pilot stated that he was happy to wait, and about 20 minutes later, the certified flight instructor (CFI) that had canceled that earlier flight called stating that the maintenance was done and the helicopter was ready to fly. The pilot and passenger planned to take an hour flight since they needed to return the helicopter back to the FBO for a tour scheduled at 7 p.m.
A witness, who was additionally a pilot, told the National Transportation Safety Board that he observed the helicopter while riding a motorcycle southbound on Blue Diamond road. He witnessed the helicopter about 1 to 2 seconds before impact. He initially saw the helicopter in the upper right-corner of his vision at an estimated 100 to 200 feet agl in a nose-up attitude and in a very steep descent angle heading opposite in his direction of travel, the report said.
The witness estimated the helicopter was moving about the same speed as the traffic (about 50 mph), because the closure rate seemed similar to the northbound automobiles. He witnessed the helicopter impact the ravine adjacent to the road (about 200 feet ahead of him and 100 feet to the right) and break apart on impact.
After making several low-level maneuvers, the track was consistent with the helicopter adjoining Blue Diamond Road and following the road heading north-northeast. The last radar hit was at 3:53 p.m., and located on the road about 1 nautical mile (nm) west-southwest from the accident site. The last 30 seconds of the track revealed the helicopter was following the road with an airspeed of about 120 to 100 kts at an altitude between 500 to 700 feet agl.
The accident site was located in the desert terrain about 10 nm from the departure airport on a bearing of 250°. The wreckage was found distributed in a ravine over a 200 foot distance on a median magnetic bearing of about 070°.
The ravine and debris field ran parallel to the road and was located about 4-5 feet below the pavement. The first identified area of impact was an approximate 5-inch line (oriented parallel to the road) of scraping and maroon-colored paint transfer across a rock and orange torque strip buried in the dirt before the rock. Adjacent to that line was another parallel line of paint transfer that was red in color. The orientation and colors were consistent with the tail rotor guard (candy-cane: white and red) and tail skid (maroon with orange torque stripe), making contact first indicative of a nose-high attitude.
The accident helicopter was the first aircraft to be fueled in the morning of the accident. According to the fueler, he arrived at the office around 7:00 a.m. and did the normal procedure of draining the truck: ½ gallon of fuel from the lower sump and ½ gallon from the filtered hose. He drained both into a white porcelain bucket and noted that both were clean, the report said.
A CFI from Airwork called for fuel, and at 8:25 a.m. the accident helicopter was fueled with 23.6 gallons topping off both the auxiliary and main fuel tanks. Shortly thereafter, another Cessna 172 received 13.3 gallons, and the pilots reported no anomalies with the fuel or their flight. The PUI scheduled with the CFI for the morning flight stated that after getting fuel, he began performing the preflight with the CFI watching behind him.
He retrieved the GATS jar fuel tester from under the right rear-seat and proceeded to sump the auxiliary fuel tank. The sample looked clean, and he sumped the main tank. The fuel appeared dirty with black and gray specs floating (similar in appearance to sand). He showed the CFI who poured out the sample in the concrete and suggested they take another sample. After taking two more samples with the same results, the CFI volunteered to clean the jar, thinking that perhaps it was dirty. He additionally found a 5-gallon bucket and dumped the fuel samples into it, which totaled about 6 to 7 samples.
The CFI then informed the Airwork mechanic of the samples who explained that he was working on several airplanes and would not be able to look at the fuel system until that afternoon. During an interview with a Safety Board investigator, the mechanic stated he did not have an opportunity to flush the fuel tanks in the helicopter. Later in the day, the CFI relayed to the PUI that the mechanic had not had the opportunity to work on the helicopter and asked him if he wanted to cancel his scheduled afternoon flight, to which the PUI replied that he did based on what occurred in the morning.
The pilot who was involved in the accident then scheduled to fly the helicopter since the PUI was not going to fly. After the flight was canceled the CFI was sumping the fuel tanks likely to ensure the tanks were clear for the accident flight. Despite numerous attempts, the CFI did not make a statement to the NTSB, and therefore it is not known what he did to the helicopter before the flight, the fuel in the helicopter, or what he said to the accident pilot.
NTSB’s Preliminary Post-Accident Examination:
The preliminary post-accident examination revealed that the exhaust was white in color consistent with a lean operation. The piston faces were additionally white and the valve faces were yellow/white. There was no evidence of a catastrophic failure with the engine. Investigator removed the gascolator at the accident site. The bowl was full with a liquid consistent in odor with that of 100LL AVGAS, but the color was an orange-yellow; there was some debris in the bowl that was akin to a gelatinous consistency (the liquid was captured in glass bottles for possible future testing). Investigators functionally tested the fuel system and fuel ran from the main tank through the system to the injector lines; the fuel screens were all clean from debris.
The helicopter was equipped with a rotor dual tachometer, and the signal to the cockpit was provided by two magnets at the main gearbox drive yoke that pass by electronic Hall Effect devices.
A Robinson representative reported that with only one magnet in place, the main rotor tachometer rpm would indicate about 50 percent of the actual rotor rpm. The post-accident examination revealed that one magnet was separated from the yoke assembly; the magnet was located on the fuselage frame near the firewall.
The magnet housing was shinny at the top of one side (the direction of rotation) consistent with contact of the magnet against a sender. The other magnet assembly remained secured to the yoke assembly. Both the housings showed a color consistent with a dark residue, and a yellow/orange mark was on both housings and senders. The yoke assembly was not damaged. There was evidence of slight damage to both senders, consistent with the magnet assembly separation.