# NTSB WPR14LA353: Robinson Helicopter R44 II, N4246Z, Pahrump, NV, August 24, 2014 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: August 24, 2014, 06:50 local (13:50 UTC) - Place: Pahrump, NV - Coordinates: 36.218055, -116.175277 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.2181&lon=-116.1753&mi=10 - Phase of flight: [Emergency descent](https://openairdocs.org/ntsb-phases/600) (OpenAirDocs' grouping) - Defining event: [Autorotation: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report November 29, 2016 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Robinson Helicopter Company, Federal Aviation Administration - NTSB case key (mKey): 89936 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR14LA353 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/89936/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=89936 - Page: https://openairdocs.org/ntsb/WPR14LA353 ## Probable cause A total loss of engine power during a practice autorotation for reasons that could not be determined because postaccident examination of the airframe and engine did not reveal any anomalies that would have precluded normal operation. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Robinson Helicopter R44 II, 24 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=7640122), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) - [Runway/land/takeoff/taxi surface: soft surface](https://openairdocs.org/ntsb-findings/03023020): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Robinson Helicopter R44 II, 4 cases](https://openairdocs.org/ntsb-findings/03023020/cases.md?model=7640122), [All aircraft, 264 cases](https://openairdocs.org/ntsb-findings/03023020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Autorotation: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Robinson Helicopter R44 II, 20 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=7640122), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Landing-landing roll: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Robinson Helicopter R44 II, 1 case](https://openairdocs.org/ntsb-events/096/sequence.md?model=7640122), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) ## Analysis The commercial pilot reported that, during a practice autorotation, a total loss of engine power occurred about 3,500 ft above ground level. The pilot made several unsuccessful attempts to restart the engine, and he subsequently performed an autorotation emergency landing. During the landing, the helicopter slid forward about 20 ft, the skids dug into the dry lakebed, and the helicopter then nosed over. Subsequently, the main rotor blades impacted the ground, and the helicopter came to rest on its side. A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The engine was test run at various power settings with no anomalies noted. ## Factual narrative On August 24, 2014, about 0650 Pacific daylight time, a Robinson Helicopter Company, R-44 II, N4246Z, sustained substantial damage while practicing an emergency autorotation, about 12 miles south of Pahrump, Nevada. The helicopter was registered to CSC Trust Company of Delaware Trustee and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. The commercial pilot sustained minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the local personal flight that departed North Las Vegas Airport (VGT), Las Vegas, Nevada, about 0605. The pilot reported a total loss of engine power at about 3,500 feet, above ground level, while rolling the throttle back for a practice autorotation. He stated the throttle was rolled back smoothly and only enough required for a small tachometer needle separation. Subsequently, the pilot made several unsuccessful attempts to restart the engine. Unable to restart the engine, the pilot performed an autorotation emergency landing. The pilot further reported that during landing, the helicopter slid forward about 20 feet; at that point, the skids dug into the dry lake bed and the helicopter nosed over. Subsequently, the main rotor blades impacted the ground, and the helicopter rolled onto its right side. Examination of the helicopter wreckage by a Federal Aviation Administration inspector revealed that the main rotor blades and tail boom were substantially damaged. Additionally, fuel was observed leaking from both tanks at the site. According to the pilot, the fuel tank quantities were about 7/8's full just prior to the accident. The helicopter was recovered to a secure storage facility for further examination. Further examination of the helicopter by the National Transportation Safety Board investigator-in-charge and a Robinson Helicopter investigator revealed no evidence of any internal damage to the fuel injected engine or its accessories was observed. The oil dipstick reading indicated a normal quantity. Continuity with all the engine controls was established. The lower spark plugs were removed and examined and all sparkplug electrodes exhibited normal wear signatures when compared to the Champion Check-A-Plug comparison chart. The crankshaft was rotated by hand and compression was obtained on all the cylinders. It was determined that an engine run could be safety accomplished. The engine was subsequently test run, using an external battery source for electrical power, and functioned normally at various power setting. The magnetos were switched from left to right and the corresponding RPM drop was observed during the run. Fuel from the helicopter was used to ensure system continuity. The main fuel tank quantity indicated about 3/8's full and the auxiliary tank about 1/4 full. No engine anomalies were observed during the engine run. The helicopter's main gear box and drive system were examined and no anomalies were noted. Flight control continuity wasestablished with the cyclic and collective. Tail rotor continuity was established in each direction from the separation point. A review of the helicopter's maintenance records revealed that the engine and airframe underwent their most recent annual inspection on December 04, 2013, at an airframe and engine total time of 444.3 hours. A Global Positioning System device was located in the wreckage and sent to the NTSB Vehicle Recorder Division for examination and readout. The device did not contain any specific information relevant to the accident. ## Aircraft - Registration: [N4246Z](https://openairdocs.org/deregistered/N4246Z-2020-06-05), registration cancelled 2020-06-05, S/N 12697, built 2009 (OpenAirDocs) - Reported make and model: ROBINSON HELICOPTER COMPANY R44 II (II) - Registry model: [Robinson Helicopter R44 II](https://openairdocs.org/model/robinson-helicopter-r44-ii) (registry code 7640122) (OpenAirDocs) - Registry engine: [Lycoming IO-540-AE1A5](https://openairdocs.org/engine/lycoming-io-540-ae1a5) (registry code 41899, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 12697 - Year built: 2009 - Airframe hours: 444.3 - Engines: LYCOMING IO-540-AE1A5 360 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, December 4, 2013 - Departed: VGT, LAS VEGAS, NV - Destination: VGT, LAS VEGAS, NV - Equipment: Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 55; injuries: minor; flight instructor, commercial; instrument ratings: helicopter; medical: class 2, with waivers/limitations; last flight review May 6, 2014; seat: right; restraint: 3-point; flight hours: 2,296 total, 1,790 in this make and model, 2,247 as pilot in command, 111 in the last 90 days, 32 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 68 °F, dew point 37 °F - Altimeter: 29.90 inHg - Observed at: DRA, 45 nm away ## 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 20140824013789A](https://openairdocs.org/incident/20140824013789A), Aug 24, 2014: Robinson Helicopter Company R44 II, Pahrump, NV, Substantial damage. While on a personal flight and operating under part 91, the pilot, who was the sole occupant, entered a power-on practice autorotation. The power was reduced… ## Other investigations on N4246Z (1) 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. - [NTSB GAA19CA110](https://openairdocs.org/ntsb/GAA19CA110), Jan 3, 2019: Robinson R44 (N4246Z), Grace, ID, substantial damage. Probable cause: The pilot's failure to maintain clearance from the power lines. ## Docket (7 files) The files NTSB released with the investigation on August 24, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=89936. 4.7 MB in all. - GPS Device Specialist's Factual Report (item 1, .PDF, 3 photos, 730 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40443665&FileExtension=.PDF&FileName=GPS%20Device%20Specialist%27s%20Factual%20Report-Master.PDF - GPS Device Specialist's Factual Report - Attachment 1 (item 2, .PDF, 17 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40443666&FileExtension=.PDF&FileName=GPS%20Device%20Specialist%27s%20Factual%20Report%20-%20Attachment%201-Master.PDF - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 3, .PDF, 1.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40443667&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Record of Conversation (item 4, .PDF, 28 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40443668&FileExtension=.PDF&FileName=Record%20of%20Conversation-Master.PDF - Airframe and Engine Examination Report (item 5, .PDF, 267 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40443669&FileExtension=.PDF&FileName=Airframe%20and%20Engine%20Examination%20Report-Master.PDF - Airplane Logbook (item 6, .PDF, 1.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40443670&FileExtension=.PDF&FileName=Airplane%20Logbook-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 7, .PDF, 329 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40443671&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Master.PDF 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.