# NTSB WPR10TA025: Mcdonnell Douglas Helicopter 500N, N521HB, Los Alamitos, CA, October 16, 2009 - Type: NTSB accident investigation - Classification: Accident · No injuries · Final report - Date: October 16, 2009, 10:45 local (17:45 UTC) - Place: Los Alamitos, CA - Coordinates: 33.79, -118.051391 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.7900&lon=-118.0514&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-flare/touchdown: Hard landing](https://openairdocs.org/ntsb-events/092) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report December 29, 2009 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 74930 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR10TA025 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/74930/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=74930 - Page: https://openairdocs.org/ntsb/WPR10TA025 ## Probable cause The flight instructor's delayed remedial action during the instructional autorotative landing, which resulted in a failure to maintain an adequate rotor rpm to avoid a hard landing. ## 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: [Mcdonnell Douglas Helicopter 500N, 1 case](https://openairdocs.org/ntsb-findings/01062052/cases.md?model=3027374), [All aircraft, 182 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md) - [Use of equip/info: use of equip/system](https://openairdocs.org/ntsb-findings/02063015): Personnel issues › Task performance · Pilot; cases with it: [Mcdonnell Douglas Helicopter 500N, 1 case](https://openairdocs.org/ntsb-findings/02063015/cases.md?model=3027374), [All aircraft, 1,391 cases](https://openairdocs.org/ntsb-findings/02063015/cases.md) - [Action: delayed action](https://openairdocs.org/ntsb-findings/02041025): Personnel issues › Action/decision · Instructor/check pilot (probable cause); cases with it: [Mcdonnell Douglas Helicopter 500N, 1 case](https://openairdocs.org/ntsb-findings/02041025/cases.md?model=3027374), [All aircraft, 894 cases](https://openairdocs.org/ntsb-findings/02041025/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Simulated/training event](https://openairdocs.org/ntsb-events/600); cases with it: [Mcdonnell Douglas Helicopter 500N, 1 case](https://openairdocs.org/ntsb-events/600/sequence.md?model=3027374), [All aircraft, 173 cases](https://openairdocs.org/ntsb-events/600/sequence.md) - [Autorotation: Attempted remediation/recovery](https://openairdocs.org/ntsb-events/060); cases with it: [Mcdonnell Douglas Helicopter 500N, 1 case](https://openairdocs.org/ntsb-events/060/sequence.md?model=3027374), [All aircraft, 1,422 cases](https://openairdocs.org/ntsb-events/060/sequence.md) - [Landing-flare/touchdown: Hard landing](https://openairdocs.org/ntsb-events/092) (defining event); cases with it: [Mcdonnell Douglas Helicopter 500N, 1 case](https://openairdocs.org/ntsb-events/092/sequence.md?model=3027374), [All aircraft, 2,102 cases](https://openairdocs.org/ntsb-events/092/sequence.md) ## Analysis The certified flight instructor (CFI) and the pilot he was instructing were practicing emergency procedures, in particular, power recovery autorotations. At 700 feet above ground level (agl), the CFI rolled the throttle off (idle) and entered the autorotation. At 50 feet agl he rolled the throttle on late, realized the ground was rapidly approaching, and decided to perform a running landing. The pilot reported that he inadvertently applied partial throttle, which did not allow the engine to regain full power. With the throttle positioned at 25 percent, the rotor rpm decayed, and when the helicopter contacted the ground, a rotor blade dipped down and struck the tail boom. The pilot stated that the helicopter and engine had no mechanical failures or malfunctions during the flight. ## Factual narrative On October 16, 2009, at 1045 Pacific daylight time, a McDonnell Douglas Helicopter 500N, N521HB, main rotor contacted the helicopter's tail boom while landing during a practice autorotation at Los Alamitos Army Airfield, Los Alamitos, California. The Huntington Beach Police Department operated the helicopter as a public-use training flight under the provisions of Title 14 Code of Federal Regulations Part 91. The certified flight instructor and pilot under instruction were not injured, the helicopter was substantially damaged. Visual meteorological conditions prevailed, and no flight plan had been filed. The flight originated at Huntington Beach Police Department helicopter pad at 0945. The certified flight instructor stated in the NTSB Pilot Accident Report that he and the pilot he was instructing were practicing emergency procedures, in particular, power recovery autorotations. He said that at 700 feet above ground level (agl) he rolled the throttle off (idle) and entered the autorotation. At 50 feet agl he rolled the throttle on late, realized the ground was rapidly approaching, and decided to perform a running landing. The pilot reported that he inadvertently applied partial throttle, which did not allow the engine to regain full power. With the throttle positioned at 25 percent, the rotor rpm decayed, and when the helicopter contacted the ground, a rotor blade struck the tail boom. He shut down the helicopter and confirmed the damage to the tail boom. The pilot stated that the helicopter and engine had no mechanical failures or malfunctions during the flight. ## Aircraft - Registration: [N521HB](https://openairdocs.org/deregistered/N521HB-2023-03-04), registration cancelled 2023-03-04, S/N LN084, built 1998 (OpenAirDocs) - Reported make and model: MCDONNELL DOUGLAS HELICOPTER 500N - Registry model: [Mcdonnell Douglas Helicopter 500N](https://openairdocs.org/model/mcdonnell-douglas-helicopter-500n) (registry code 3027374) (OpenAirDocs) - Registry engine: [Allison 250-C20 series](https://openairdocs.org/engine/allison-250-c20-series) (registry code 03020, turbo-prop) (OpenAirDocs) - Category: Helicopter - Serial number: LN084 - Airframe hours: 8780 - Engines: ALLISON 250-C20 SER 420 horsepower turbo shaft - Damage: Substantial damage - Flight: Public aircraft - local, Part 91 - Operator: City Of Huntington Beach - Registered owner: City Of Huntington Beach - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, August 10, 2009 - Departed: CL65, Huntington Beac, CA - Destination: KSLI, Los Alamitos, CA - Airport: KSLI, Los Alamitos Army Airfield, runway 22L, 8,000 × 200 ft, concrete ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 34; injuries: none; commercial, flight instructor; medical: class 2; last flight review December 20, 2007; seat: right; flight hours: 1,841 total, 1,790 in this make and model, 1,792 as pilot in command, 140 in the last 90 days, 46 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: variable at 3 knots - Visibility: 6 statute miles - Lowest ceiling: none - Temperature: 79 °F, dew point 66 °F - Altimeter: 29.89 inHg - Observed at: SKLI ## 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 20091016053579A](https://openairdocs.org/incident/20091016053579A), Oct 16, 2009: Mcdonnell D 500N, Los Alamitos, CA, Substantial damage. During my interview with the pilot, he stated that they were about one hour into the training flight when he decided to demonstrate a power recovery… ## Other investigations on N521HB (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 WPR22FA101](https://openairdocs.org/ntsb/WPR22FA101), Feb 20, 2022: Mcdonnell Douglas 500N (N521HB), Newport Beach, CA, substantial damage, 1 fatal. Probable cause: The helicopter’s encounter with unanticipated right yaw during a low-altitude, low-airspeed, tight-radius orbit. Contributing to the accident was the pilot’s distraction during the orbit, which… ## Docket (1 files) The files NTSB released with the investigation on October 29, 2009, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=74930. 665 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 665 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40320478&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.