# NTSB WPR11CA121: Robinson R44, N441TB, Ogden, UT, February 4, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: February 3, 2011, 17:20 local (Feb 4, 2011, 00:20 UTC) - Place: Ogden, UT - Coordinates: 41.352222, -112.194168 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.3522&lon=-112.1942&mi=10 - Phase of flight: [Emergency descent](https://openairdocs.org/ntsb-phases/600) (OpenAirDocs' grouping) - Defining event: [Autorotation: Hard landing](https://openairdocs.org/ntsb-events/092) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report June 8, 2011 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: FAA FSDO - NTSB case key (mKey): 78278 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR11CA121 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/78278/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=78278 - Page: https://openairdocs.org/ntsb/WPR11CA121 ## Probable cause The certified flight instructor’s failure to maintain adequate main rotor blade rpm during a practice autorotation, resulting in a hard landing and rollover. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: prop/rotor parameters](https://openairdocs.org/ntsb-findings/01062052): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Robinson Helicopter R44, 15 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md?model=7640120), [All aircraft, 182 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Instructor/check pilot (probable cause); cases with it: [Robinson Helicopter R44, 40 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=7640120), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Terrain: wet/muddy terrain](https://openairdocs.org/ntsb-findings/03021035): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Robinson Helicopter R44, 2 cases](https://openairdocs.org/ntsb-findings/03021035/cases.md?model=7640120), [All aircraft, 110 cases](https://openairdocs.org/ntsb-findings/03021035/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Autorotation: Hard landing](https://openairdocs.org/ntsb-events/092) (defining event); cases with it: [Robinson Helicopter R44, 16 cases](https://openairdocs.org/ntsb-events/092/sequence.md?model=7640120), [All aircraft, 2,102 cases](https://openairdocs.org/ntsb-events/092/sequence.md) - [Landing-flare/touchdown: Roll over](https://openairdocs.org/ntsb-events/097); cases with it: [Robinson Helicopter R44, 17 cases](https://openairdocs.org/ntsb-events/097/sequence.md?model=7640120), [All aircraft, 261 cases](https://openairdocs.org/ntsb-events/097/sequence.md) ## Analysis After completing several practice landings and autorotations at the airport, the certified flight instructor (CFI) and student pilot departed for the practice area. The CFI demonstrated straight-in and 180-degree autorotations; the first 180-degree attempt began at 6,000 feet mean sea level and at 55-60 knots. During the second 180-degree attempt, he started about 200 feet lower. The airspeed bled off to about 50 knots during the turn, and the main rotor blades’ rpms began decaying rapidly. About 200 feet above ground level the CFI attempted a power recovery, but the rpms did not increase with an increase in throttle. He unsuccessfully attempted to flair to bring the rpms back before attempting a full down autorotation. He put the helicopter in a level attitude prior to contact with the ground and the helicopter bounced upon initial contact; on the second contact, the right skid dug into the muddy ground and the helicopter rolled onto its right side. The helicopter sustained substantial damage to the airframe and rotor blades. The pilots stated that the helicopter had no mechanical failures or malfunctions prior to the accident. ## Factual narrative After completing several practice landings and autorotations at the airport, the Certified Flight Instructor (CFI) and student pilot departed for the practice area. The CFI demonstrated straight in and 180-degree autorotations; the first 180-degree attempt began at 6,000 feet mean sea level and 55-60 knots. During the second 180-degree attempt, he started about 200 feet lower. The airspeed bled off to about 50 knots during the turn, and the main rotor blades’ revolutions per minute (rpm) began decaying rapidly. About 200 feet above ground level (agl), the CFI attempted a power recovery, but the rpm did not increase with an increase in throttle. He attempted to flair to bring the rpm back, but this did not work either. He attempted a full down autorotation, and put the helicopter in a level attitude prior to contact with the ground. The helicopter bounced; on the second contact, the right skid dug into the muddy ground, and rolled onto its right side. The pilots were not injured, and extricated themselves from the wreckage. The helicopter sustained substantial damage to the airframe and rotor blades. The pilots stated that the helicopter had no mechanical failures or malfunctions. ## Aircraft - Registration: [N441TB](https://openairdocs.org/aircraft/N441TB), registered now, S/N 0631, built 1999 (OpenAirDocs) - Reported make and model: ROBINSON R44 (UNDESIGNAT) - Registry model: [Robinson Helicopter R44](https://openairdocs.org/model/robinson-helicopter-r44) (registry code 7640120) (OpenAirDocs) - Registry engine: [Lycoming 0-540 series](https://openairdocs.org/engine/lycoming-0-540-series) (registry code 41532, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 0631 - Airframe hours: 1676 - Engines: Lycoming O-540-F1B5 250 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Whirlybird Helicopters LLC - Registered owner: Av8 LLC - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, January 13, 2011, 32 hours before - Departed: OGD, Ogden, UT - Destination: OGD, Ogden, UT - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 24; injuries: none; flight instructor, commercial; instrument ratings: helicopter; medical: class 1, without waivers/limitations; last flight review July 29, 2009; seat: left; flight hours: 964 total, 661 in this make and model, 806 as pilot in command, 200 in the last 90 days, 55 in the last 30 days - Student pilot; age 30; injuries: none; private; instrument ratings: helicopter; medical: class 2, without waivers/limitations; seat: right; flight hours: 172 total, 109 as pilot in command, 29 in the last 90 days, 10 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 25 °F, dew point 7 °F - Altimeter: 30.46 inHg - Observed at: KOGD ## 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 20110203000739A](https://openairdocs.org/incident/20110203000739A), Feb 3, 2011: Robinson He R44, Ogden, UT, Substantial damage. During a demonstration practice engine out autorotation, the pilot mismanaged the controls resulting in low rotor RPM and slower than normal airspeedpilot used… ## Docket (1 files) The files NTSB released with the investigation on March 7, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=78278. 1.8 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40344717&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.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.