# NTSB ANC12CA032: Robinson Helicopter R22 Alpha, N121MR, Palmer, AK, April 21, 2012 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: April 21, 2012, 15:00 local (23:00 UTC) - Place: Palmer, AK - Coordinates: 61.672779, -149.40277 - Nearby events: https://openairdocs.org/map.md?lat=61.6728&lon=-149.4028&mi=10 - Phase of flight: [Standing](https://openairdocs.org/ntsb-phases/150) (OpenAirDocs' grouping) - Defining event: [Standing-engine(s) operating: Loss of control on ground](https://openairdocs.org/ntsb-events/230) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report July 18, 2012 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA Anchorage FSDO-03 - NTSB case key (mKey): 83452 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC12CA032 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/83452/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=83452 - Page: https://openairdocs.org/ntsb/ANC12CA032 ## Probable cause The pilot's selection of unsuitable terrain for landing, which resulted in a tailrotor strike. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Robinson Helicopter R22 ALPHA, 1 case](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=7640104), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) - [Terrain: snowy/icy terrain](https://openairdocs.org/ntsb-findings/03021030): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Robinson Helicopter R22 ALPHA, 1 case](https://openairdocs.org/ntsb-findings/03021030/cases.md?model=7640104), [All aircraft, 77 cases](https://openairdocs.org/ntsb-findings/03021030/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Standing-engine(s) operating: Loss of control on ground](https://openairdocs.org/ntsb-events/230) (defining event); cases with it: [Robinson Helicopter R22 ALPHA, 1 case](https://openairdocs.org/ntsb-events/230/sequence.md?model=7640104), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) - [Standing-engine(s) operating: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Robinson Helicopter R22 ALPHA, 2 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=7640104), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot flew to a practice area and landed the helicopter on what the pilot thought was firm snow. As he landed, the helicopter suddenly broke through the surface and its tailrotor struck the snow. The pilot repositioned the helicopter and the tailrotor gearbox chip detector light illuminated. An examination showed that the tailrotor driveshaft had sheared. ## Factual narrative The pilot flew to a practice area and landed the helicopter on what the pilot thought was firm snow. As he landed, the helicopter suddenly broke through the surface, and its tailrotor struck the snow. The pilot repositioned the helicopter, and the tailrotor chip light illuminated. An inspection showed that the tailrotor driveshaft had sheared. ## Aircraft - Registration: [N121MR](https://openairdocs.org/deregistered/N121MR-2018-04-04), registration cancelled 2018-04-04, S/N 0496, built 1985 (OpenAirDocs) - Reported make and model: ROBINSON HELICOPTER R22 ALPHA - Registry model: [Robinson Helicopter R22 ALPHA](https://openairdocs.org/model/robinson-helicopter-r22-alpha) (registry code 7640104) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Helicopter - Serial number: 0496 - Airframe hours: 2451 - Engines: Lycoming O-320 A2B 160 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Pollux Aviation Limited, doing business as Pollux Aviation - Registered owner: Castor Aviation Ltd - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, April 18, 2012 - Departed: 4AK6, Palmer, AK - Destination: 4AK6, Palmer, AK - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 33; injuries: none; flight instructor, commercial; instrument ratings: helicopter; medical: class 2, without waivers/limitations; last flight review July 16, 2010; seat: right; flight hours: 1,295 total, 1,176 in this make and model, 1,212 as pilot in command, 14 in the last 90 days, 12 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 ## 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 20120421007209A](https://openairdocs.org/incident/20120421007209A), Apr 21, 2012: Robinson Helicopter R22 ALPHA, Palmer, AK, Substantial damage. Pilot landed off airport in the snow. When collective was reduced a/c tilted to the rear. When pilot picked up the a/c the tail rotor struck the snow. ## Other investigations on N121MR (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 ANC17LA013](https://openairdocs.org/ntsb/ANC17LA013), Dec 18, 2016: Robinson Helicopter R22 (N121MR), Palmer, AK, substantial damage. Probable cause: The pilot's failure to maintain main rotor revolutions per minute (RPM) during a pinnacle landing, which resulted in a main rotor stall condition, a loss of control, and a subsequent impact with… ## Docket (1 files) The files NTSB released with the investigation on May 25, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=83452. 2.7 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 2.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40368568&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.