# NTSB CEN11CA325: Robinson Helicopter R44 II, N921JM, Golden, CO, May 8, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: May 8, 2011, 14:30 local (20:30 UTC) - Place: Golden, CO - Coordinates: 39.73389, -105.245002 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.7339&lon=-105.2450&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Settling with power/vortex ring state](https://openairdocs.org/ntsb-events/244) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report August 3, 2011 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA FSDO - NTSB case key (mKey): 79061 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN11CA325 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/79061/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=79061 - Page: https://openairdocs.org/ntsb/CEN11CA325 ## Probable cause The pilot’s decision to operate the helicopter at a high density altitude near terrain, which resulted in a settling with power condition. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: altitude](https://openairdocs.org/ntsb-findings/01062012): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible (probable cause); cases with it: [Robinson Helicopter R44 II, 39 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md?model=7640122), [All aircraft, 1,310 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md) - [Aircraft capability](https://openairdocs.org/ntsb-findings/01061000): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible (probable cause); cases with it: [Robinson Helicopter R44 II, 3 cases](https://openairdocs.org/ntsb-findings/01061000/cases.md?model=7640122), [All aircraft, 57 cases](https://openairdocs.org/ntsb-findings/01061000/cases.md) - [Temp/humidity/pressure: high density altitude](https://openairdocs.org/ntsb-findings/03031020): Environmental issues › Conditions/weather/phenomena · Effect on operation (probable cause); cases with it: [Robinson Helicopter R44 II, 11 cases](https://openairdocs.org/ntsb-findings/03031020/cases.md?model=7640122), [All aircraft, 278 cases](https://openairdocs.org/ntsb-findings/03031020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Settling with power/vortex ring state](https://openairdocs.org/ntsb-events/244) (defining event); cases with it: [Robinson Helicopter R44 II, 6 cases](https://openairdocs.org/ntsb-events/244/sequence.md?model=7640122), [All aircraft, 52 cases](https://openairdocs.org/ntsb-events/244/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Robinson Helicopter R44 II, 95 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=7640122), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The helicopter was following participants in a downhill skateboard race in mountainous terrain. The pilot had just performed a left-pedal turn and the helicopter was facing upslope to the mountain. The low rotor warning sounded and the pilot lowered the collective and increased throttle. The pilot stated that the engine did not respond so he continued to lower the collective and looked for a place to land. During the forced landing on the downsloping terrain the helicopter came to rest on its nose, resulting in substantial damage to the main rotor, skid tubes, and tail boom. Postaccident examination of the helicopter, engine, and systems, revealed no anomalies. The density altitude was calculated to be 10,600 feet. The pilot calculated the in-ground-effect hover to be 8,500 feet pressure altitude, the out-of-ground-effect hover to be 5,000 feet pressure altitude, and estimated the gross weight to be 2,320 pounds. ## Factual narrative The helicopter was following participants in a downhill skateboard race in mountainous terrain. The pilot had just performed a left pedal turn and the helicopter was facing upslope to the mountain. The low rotor warning sounded and the pilot lowered collective and increased throttle. The pilot stated that the engine did not respond so he continued to lower the collective and looked for a place to land. During the forced landing on the down sloping terrain, the helicopter came to rest on its nose resulting in substantial damage to the main rotor, skid tubes, and tail boom. An examination of the helicopter, engine, and systems, conducted by the Federal Aviation Administration, revealed no anomalies. The density altitude was calculated to be 10,600 feet. The pilot calculated the in ground effect hover to be 8,500 feet pressure altitude, the out of ground effect hover to be 5,000 feet pressure altitude, and estimated the gross weight to be 2,320 pounds. ## Aircraft - Registration: [N921JM](https://openairdocs.org/aircraft/N921JM), registered now, S/N 10565, built 2004 (OpenAirDocs) - Reported make and model: ROBINSON HELICOPTER COMPANY R44 II - Registry model: [Robinson Helicopter R44 II](https://openairdocs.org/model/robinson-helicopter-r44-ii) (registry code 7640122) (OpenAirDocs) - Registry engine: [Lycoming IO-540 series](https://openairdocs.org/engine/lycoming-io-540-series) (registry code 41530, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 10565 - Airframe hours: 1185.5 - Engines: LYCOMING IO-540 SER 300 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial observation, Part 91 - Operator: Colorado Helicopter Inc - Registered owner: Thunderbird Aviation LLC - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, March 11, 2011 - Departed: KBJC, Denver, CO - Destination: KBJC, Denver, CO ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 33; injuries: none; commercial, flight instructor; instrument ratings: helicopter; medical: class 1, without waivers/limitations; last flight review July 29, 2009; seat: left; flight hours: 1,771 total, 1,556 in this make and model, 1,685 as pilot in command, 120 in the last 90 days, 52 in the last 30 days, 6 in the last 24 hours - Student pilot; age 32; injuries: none; private; medical: class 2, without waivers/limitations; seat: right; flight hours: 164 total, 35 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 200° at 8 knots - Visibility: 60 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point -0 °F - Altimeter: 29.61 inHg - Observed at: KBLC ## 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 20110508008649A](https://openairdocs.org/incident/20110508008649A), May 8, 2011: Robinson Helicopter Company R44 II, Golden, CO, Substantial damage. On may 8, 2011, at 1430 hours MDT, a Robinson R44 helicopter, N921JM, was substantially damaged while maneuvering in Golden, Colorado. There were 3 sob's with… ## Docket (2 files) The files NTSB released with the investigation on May 27, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=79061. 344 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 279 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40348217&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Record of Telephone Conversation (item 2, .PDF, 65 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40348354&FileExtension=.PDF&FileName=Record%20of%20Telephone%20Conversation-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.