MIA00GA121
MIA00GA121

HISTORY OF FLIGHT

On March 27, 2000, about 0740 central standard time, a Hughes HU-269C, N1110N, registered to Go Helicopters, Inc., operating as a Title 14 CFR Part 91 public-use flight, crashed while maneuvering near Del Rio, Texas. Visual meteorological conditions prevailed and no flight plan was filed. The helicopter was destroyed and the commercially-rated pilot and a passenger received fatal injuries. The flight originated about 10 minutes before the accident.

The flight was a coyote eradication mission, contracted and controlled by a coalition of USDA, local ranchers, and Val Verde County. The flight had just lifted off from its travel trailer and had conducted a radio check-in with the ground crew located about 6 miles northeast. When radio contact was lost, the ground crew started a search and found the wreckage about 2 miles northeast of its liftoff point. There were no eyewitnesses to the crash.

PERSONNEL INFORMATION

The pilot held a private pilot certificate with ratings for airplane, single engine land, and a commercial pilot certificate for helicopter. His most recent FAA second-class medical certificate was issued on June 9, 1999, without limitations. U.S. Department of Agriculture helicopter pilot proficiency records indicate that at the time of the pilot's proficiency check ride on November 17, 1999, he had logged 2,517 flight hours of which 2,260 were as pilot-in-command, (PIC)and 2,000 were in the HU-269C type helicopter. The results of the check ride were recorded as satisfactory, except for the examiner's remark, "need to use checklist".

The wife of the pilot provided a chronological history of the pilot's activities for the 4 days preceding the accident. Activities included weekend social interrelations with family and friends, relatively low priority personal property upkeep and work activities, and preparing for the next week's flying schedule. Rest time, anticipated next week's work, and diet appeared non-stressful.

AIRCRAFT INFORMATION

The helicopter had both left and right entry doors removed and an aluminum strap external cargo rack was installed adjacent to the right doorway for varmint carcass hauling. The right seat flight and engine controls and the center seat had been removed to accommodate the gunner and a centerline tray for ammunition and marking streamers. The optional 19-gallon left side auxiliary fuel tank was installed. Five-point restraining harnesses with single-point, rotary-latching mechanisms were installed at both crew seats. The rotorcraft had undergone a 100-hour inspection on January 22, 2000, at an airframe total time of 3976.7 hours and a Hobbs time of 1781.9 hours. At that time a new tail boom, serial No. 0990655, was installed. The total time on the airframe at the accident site was 4026.8 hours.

The Lycoming HIO-360-D1A engine, serial No. L-21305-51A, had received a field major overhaul and signed off by an FAA certified mechanic on March 19, 2000, at an airframe total time of 3995.3 hours and a Hobbs time of 1800.5 hours, or about 31.5 flight hours prior to the accident. A new alternator was installed at that time. There was no record that the AC diaphragm fuel pump was replaced at engine overhaul per Textron Lycoming SB 240Q, or that the fuel system components, per Textron Lycoming SI 1404A, or that the magnetos, per Textron Lycoming SB 515, were overhauled at engine overhaul.

On the Thursday prior to the Monday accident, a company mechanic had changed the voltage regulator because the battery was being overcharged and spewing battery acid from the cap vent holes. A subsequent test of the electrical system proved the overcharging condition still existed. The Friday before the accident, the over-voltage relay was replaced and the overcharging problem appeared to clear up. On Saturday the helicopter flew a cattle-herding mission for .7 hours by the accident pilot. No further report of overcharging was noted.

METEOROLOGICAL INFORMATION

Visual meteorological conditions prevailed at the time of the accident, and density altitude was 1,703 feet. Meteorological information is contained in this report on page 3, under, "Weather Information". WRECKAGE AND IMPACT INFORMATION

The accident site is located on the Hutto Ranch, about 7 miles north of Del Rio, 3.5 miles east of U.S. Highway 277/377 at coordinates N29 29.15 by W100 52.27 degrees. The terrain's surface is hard dirt and rock with knee-high scrub brush and cactus growth at about 1,000 feet elevation. An occasional gully or ravine, 20 to 50 feet deep, threads throughout the generally rolling terrain. The wreckage site was situated on flat, roughly shrubbed terrain adjacent to a 30-foot deep ravine. The wreckage path was oriented about 30 degrees, magnetic, about 70 feet in length, and coincided with a straight line between the point of lift off near the ranch house and the ground crew's location. The first ground scar contained pieces of a tail rotor blade's tip/trailing edge and 14 feet further along the path revealed a ground scar made by the vertical stabilizer. Twenty-three feet further revealed spewed engine crankcase oil. The pattern of spewed oil was downward and forward, (30 degrees, magnetic) and littered with pieces of fractured crankcase. The airframe came to rest 33 feet further along the wreckage path, having rolled so that the main rotor shaft was about 110 degrees from the vertical, viewed from behind the wreckage. Examination of airframe damage and ground scars revealed characteristics of a steep, nose high approach and high-g ground contact and bounce with no or low engine and rotor rpm. The center frame section and the landing skids were heavily distorted. The tail boom had separated at its forward attach point and lay right of wreckage path centerline between the first ground scar and the main wreckage. The tail rotor was still attached to the tail boom. The aft portion of the tail rotor drive shaft was still contained within the tail boom and its fracture site was in-line with the separation site of the tail boom. The forward section of the tail rotor drive shaft was found to the right of wreckage path centerline, outboard of the tail boom. The tail boom and its left support strut revealed a low energy main rotor blade collision impression. The boom mounted vertical stabilizer had sustained ground collision crushing. Neither the main nor the tail rotor drive systems revealed evidence of rotational damage. The lower coupling drive shaft, (short shaft) revealed non-rotational damage to the splines at the engine end. There was no leading edge scarring of the three main rotor blades or the tail rotor blades. There was no evidence of shotgun damage to any blade. One of the two tail rotor blades revealed non-rotational trailing edge compression damage that matched the ground scars and blade pieces found at the first ground scar. The main rotor hub assembly revealed evidence of extreme blade flapping. The red main rotor blade was found bent upward about 45 degrees just outboard of the blade doublers; the blue blade was bent upward about 10 degrees just outboard of the blade doublers; and the yellow blade, about 45 degrees downward.

Both externally mounted fuel tanks received heavy impact damage. The right, (30 gallon) main tank was heavily wrinkled, but still attached. The left, (19 gallon) auxiliary tank had separated, was heavily wrinkled and punctured, and was found adjacent to the wreckage at 9 o'clock, viewed from behind the wreckage. Both tanks contained residual fuel that appeared clean with the characteristic blue color of 100LL octane. The fuel tested negative for water content.

The site was littered with live shotgun shells, paper streamers, and a very pistol. A wristwatch was found, having stopped at 0730. A shotgun, not recently fired, was found in the wreckage. The pilot was found lying adjacent to and behind the airframe. The crewman was found 18 feet forward of the airframe. Examination of both occupant restraint assemblies revealed that only the lap belt portions of the five-point restraint harnesses had been engaged in their respective single-point rotary locking receptacles. The pilot's lap belt had failed due to tension overload of the webbing. The crewman's complete harness assembly had torn away from its bulkhead mounting, and was found near him. Both crew seats and their respective mounting framework had sustained heavy downward deformation. The instrument panel had separated at the floor attach points. All flight control components below the transmission received heavy impact damage. The transmission drive belts and belt actuator appeared to be in good condition. The clutch cables, clutch control spring assembly, pulleys, and mounting hardware appeared functional, precrash. The clutch linear actuator shaft was found fully retracted indicating that the clutch spring assembly was engaged at ground impact. Two wire cable fractures were removed and saved for NTSB Materials Laboratory analysis, (1) the cable attached to the clutch linear actuator, and, (2) the cable attached to the left seat directional control system aft of the forward pulley/bellcrank assembly. NTSB Materials Laboratory analysis revealed both fracture sites contained elongation damage typical of overstress or impact separation. The horizontally mounted Lycoming HIO-360-D1A engine, serial no. L-21305-51A, was still attached to the heavily distorted airframe. The cooling fan and shroud, as well as the engine driven accessories revealed evidence of little or no rotation at ground collision. The fuel injector servo, engine fuel pump, and ignition harness were heavily crushed and broken loose from the engine. The oil sump and induction system were crushed and destroyed. The under-engine exhaust connector pipes were crushed flat, but revealed no evidence of precrash obstruction. The spark plugs were the correct type per Lycoming specifications. The top plugs for each of the four cylinders were removed and showed normal electrode deposit coloration per Champion Spark Plugs Check-a-Plug chart AV-27. The left magneto produced spark at all four posts when hand actioned. The right magneto case was fractured and could not be actioned. Ignition timing appeared correct, relative to piston position. All cylinders revealed good compression, and valve and accessory drive trains were functional and properly positioned. The fuel injector servo, fuel injection nozzles, and the right magneto underwent repair station examination with FAA oversight. According to the FAA inspector's statement, "No defects were observed that would cause an engine malfunction to occur."

The Textron-Lycoming HIO-360-D1A engine, serial no. L-21305-51A, was boxed and shipped to the factory for disassembly examination, with FAA oversight. Valve guide to valve stem tolerances were within factory tolerances. Slight twisting of three of the four connecting rods was revealed, but was within factory tolerances. The no.3 main bearing revealed slight overlay fatigue, but the condition is normal for an overhauled engine being broken in. No condition was found to preclude normal engine operation. The factory report of the engine examination, as well as the FAA inspector's statement, is an attachment to this report.

Subsequent re-examination of the airframe wreckage after removal to a company hangar near San Antonio revealed a spent 12-gauge shotgun shell lying loose under the seat support panel. With the seat cushions installed, the only way the shell could have migrated to its as-found location was through a slot at the aft cabin bulkhead centerline, where the seatback and seat cushions meet. With the removal of the right seat collective/throttle control column, only the column socket and the throttle bell crank/correlator assembly dwelled in the bottom of the slot. The correlator's function is to provide linear "lead-in" of about 500 to 700 engine rpm "auto-increase" of the throttle as the collective control is increased from flat pitch. The action also works in reverse, as the collective is decreased. The brass end of the cartridge revealed an impression of a 1/4-inch bolt-end, and when reinserted so that the only 1/4-inch bolt-end on the bell crank/correlator assembly fit the impression, it served to jam the designed action of the throttle correlator in the decrease engine power direction.

MEDICAL AND PATHOLOGICAL INFORMATION

Postmortem examination of the pilot was conducted by Dr.Vincent J.M. Di Maio, M. D., Chief Medical Examiner, Bexar County, Texas, on March 28, 2000. The cause of death was attributed to traumatic injuries sustained in the helicopter crash. No findings that could be considered causal were noted. Toxicological tests were conducted at the Federal Aviation Administration Research Laboratory, Oklahoma City, Oklahoma. The tests were negative for ethanol, basic, acidic, and neutral drugs.

Postmortem examination and inquest for the gunner was conducted by Judge Dorothy Weddle, Justice of the Peace, Val Verde County, Texas, on March 27, 2000. The cause of death was attributed to injuries sustained in the accident.

TESTS AND RESEARCH

According to the USDA accident investigator assigned as a party to the investigation, he returned to San Antonio on April 12, 2000, to try to duplicate the shotgun cartridge jamming scenario using an undamaged Hughes 269C and other, identical, shotgun cartridges. It was found that the jam between the throttle bell crank and the correlator would cause engine rpm to not automatically decrease as collective was being decreased. During the simulation, in each case when the throttle grip was forced toward the idle position, the jammed shell revealed crush markings identical to the markings found on the accident rotorcraft cartridge. Two reports of the simulations, as well as a possible accident scenario, are attachments to this report.

The NTSB and Schweizer Aircraft Corporation, using the accident cartridge and an undamaged HU-269C conducted subsequent duplicate jamming scenarios. Acknowledging that vigorous collective, throttle, and cyclic inputs were being applied as in chasing wild animals, the jam could not be duplicated, and the cartridge fell into the dead space under the seat panels each time. To induce the jam, the cartridge had to be hand positioned between the throttle bell crank and the correlator. When the jam was hand induced, throttle action could be restricted in the decrease power direction only, and not in the increase power direction. In each case of restricted movement in the decrease power direction, a stronger than normal twisting motion by the pilot could overcome the jam.

ADDITIONAL INFORMATION

The wreckage, less those components listed on the wreckage release form, was released to a representative of the operator and signed for on March 29, 2000. All components, including the maintenance records were returned to the owner on January 12, 2001.

Those additional investigative parties not listed in the factual data section of this report are: (1) Gregory M. Obert, President, Go Helicopters (2) Steve Gleason, Engineering Technical Manager, Schweizer Aircraft

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