# NTSB LAX96LA168: Hughes 369D, N519BH, Yerington, NV, April 14, 1996 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 14, 1996, 11:55 local (18:55 UTC) - Place: Yerington, NV - Coordinates: 38.870758, -119.139427 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.8708&lon=-119.1394&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report December 16, 1996 - Report: Approved by Office Director - NTSB case key (mKey): 29419 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX96LA168 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/29419/pdf - Page: https://openairdocs.org/ntsb/LAX96LA168 ## Probable cause the partial loss of engine power and the pilot's misjudged flare during an autorotation landing in soft dirt with excessive forward speed. The power loss resulted from flight operations in an environment which debris contaminated the engine's nozzle port and compressor assembly. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - nonmechanical, cruise - normal - fuel system,nozzle - contamination (cause) - compressor assembly,blade - dirty(foggy) (cause) - Forced landing, emergency descent/landing - autorotation - performed, pilot in command - Roll over, landing - flare/touchdown - flare - misjudged, pilot in command (cause) - terrain condition - open field - terrain condition - soft (contributing factor) ## Analysis The pilot experienced a total loss of engine power while cruising between 200 and 300 feet above ground level and at an airspeed of 100 knots. The pilot reported that the engine noise resembled the same whining as if it were in a shut down mode. The pilot entered an autorotation and landed in an open field approximately 0.5 miles from his airstrip. The accident site examination revealed that the helicopter had touched down with forward speed and made depressions in the soft ground over a distance of 25 to 30 feet. The helicopter rolled onto its side and a main rotor blade severed the tail boom. Tail rotor blade and drive shaft components separated from the helicopter and were found 200 feet from the main wreckage. The last annual inspection was performed 6 months prior to the accident flight and the aircraft had flown 16.9 hours. Also, the last compressor wash was performed about 2 months prior to the flight and had flown 8 hours since then. The postaccident engine examination revealed accumulated nozzle port debris and dirty compressor blades and vanes. The engine flamed out during its first test run and, during subsequent tests, it produced power 7.8 percent below specifications. ## Factual narrative HISTORY OF FLIGHT On April 14, 1996, at 1155 hours Pacific daylight time, a Hughes 369D, N519BH, owned and operated by the pilot, experienced a loss of engine power during cruise flight. The helicopter was substantially damaged during landing in an open field about 30 miles south of Yerington, Nevada. Neither the private pilot nor the two passengers were injured during the personal flight. Visual meteorological conditions prevailed, and no flight plan was filed. The round robin flight originated at 1110 from the pilot's private airstrip at the Flying M. Ranch in Yerington. According to the pilot, he experienced a total loss of engine power while cruising between 200 and 300 feet above ground level at an airspeed of 100 knots. The pilot reported that "the engine noise resembled the same whining as if it were in a shut down mode." The pilot entered an autorotation and landed on a freshly plowed soft dirt field approximately 0.5 miles from his private airstrip. After touchdown, the helicopter rolled onto its right side. AIRCRAFT INFORMATION: The helicopter was maintained on an annual inspection program and had been operated for about 29 flight hours during the previous year. Since receiving its last annual inspection on October 11, 1995, the helicopter had been operated for about 16.9 hours. The last recorded engine maintenance was a compressor wash which was completed on February 7, 1996, at 1,785.0 hours. The helicopter's maintenance records were examined by representatives from the Federal Aviation Administration (FAA), McDonnell Douglas Helicopter Systems (MDD), and the Allison Engine Company. None of the parties reported observing any recorded deficiencies pertinent to the accident flight. WRECKAGE AND IMPACT INFORMATION Under FAA supervision, the helicopter was examined by the MDD and Allison Engine participants. The parties reported observing skid-like depressions over a 25- to 30-foot-long path between the initial point of ground impact and the main wreckage. Based upon structural deformation signatures and the wreckage fragmentation pattern, MDD opined that during the landing sequence a main rotor blade contacted and severed the helicopter's tail boom. Tail rotor blade and tail rotor drive shaft components were located over 200 feet from the main wreckage. MDD reported that the physical evidence indicated "at least partial engine power . . . was present at the time (of ground impact). . . . No evidence was found of any preexisting system or component failure or malfunction that would have caused or contributed to the mishap." TESTS AND RESEARCH On May 17, 1996, the helicopter's engine was inspected and test run at Allison Engine Company's Indianapolis, Indiana, facilities. In pertinent part, the FAA made the following observations: ". . . Accumulated debris encompassed the nozzle port. It was located towards an area of about 1/4 inch over the air atomizer path. Furthermore, fine dust particles were noted on the outer compressor case. The initial run was normal, but at 4,900 (N1) speed the engine flamed-out. During the second run the engine was operated at take-off power, flight idle, accelerations, decelerations and different power settings." An analysis of the test cell data revealed that during the tests the engine had operated below the targeted torque required for that specific engine model. According to the Allison Engine Company, during the engine test run power was produced at ". . . a level 7.8 percent below normal performance levels. The compressor was found to be extremely dirty on both blades and vanes throughout all stages." In conclusion, the Allison participant opined that the decreased engine performance was most probably the result of the dirty compressor. Also, during the accident sequence at the point of ground contact, engine power was likely being applied to the main rotor and tail rotor drives. ## Aircraft - Registration: N519BH (not matched to a registry record) - Reported make and model: Hughes 369D - Category: Helicopter - Serial number: 854D - Airframe hours: 1793 - Engines: Allison 250-C20B 420 horsepower turbo shaft - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: William Barron Hilton - Airworthiness certificate: Standard, Normal - Last inspection: Annual, October 11, 1995, 17 hours before - Departed: NV ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 68; private; airplane ratings: single-engine land, multi-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 6,348 total, 176 in this make and model, 5,539 as pilot in command, 8 in the last 90 days, 8 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 315° at 5 knots, gusting 7 - Visibility: 50 statute miles - Lowest ceiling: none - Temperature: 70 °F ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19960414007219A](https://openairdocs.org/incident/19960414007219A), Apr 14, 1996: Hughes 369D, Hawthorne, NV, Substantial damage. Engine failed, crashed in a field. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.