# NTSB WPR14LA198: Rockwell International S 2R, N702CB, Medicine Lake, MT, May 21, 2014 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: May 21, 2014, 14:30 local (20:30 UTC) - Place: Medicine Lake, MT - Coordinates: 48.513332, -104.385276 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=48.5133&lon=-104.3853&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-flare/touchdown: Ground collision](https://openairdocs.org/ntsb-events/200) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report December 14, 2015 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: FAA-FSDO - NTSB case key (mKey): 89248 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR14LA198 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/89248/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=89248 - Page: https://openairdocs.org/ntsb/WPR14LA198 ## Probable cause The pilot’s failure to maintain airplane control and sufficient altitude to clear terrain during a low-altitude maneuver. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Rockwell International S-2R, 7 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=7630202), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Performance/control parameters: altitude](https://openairdocs.org/ntsb-findings/01062012): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Rockwell International S-2R, 3 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md?model=7630202), [All aircraft, 1,310 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Loss of control in flight](https://openairdocs.org/ntsb-events/240); cases with it: [Rockwell International S-2R, 4 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=7630202), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Landing-flare/touchdown: Ground collision](https://openairdocs.org/ntsb-events/200) (defining event); cases with it: [Rockwell International S-2R, 1 case](https://openairdocs.org/ntsb-events/200/sequence.md?model=7630202), [All aircraft, 618 cases](https://openairdocs.org/ntsb-events/200/sequence.md) ## Analysis The pilot reported that he was maneuvering the airplane into a left banking turn after an aerial application. He added that, the next thing that he could remember, was that he could not arrest the airplane's descent and that it was heading toward the ground. The pilot tried to correct the airplane's attitude by pulling up, but the airplane subsequently impacted terrain. Wreckage examination revealed that the left wing contacted the ground first. Engine examination and component testing did not reveal evidence of any preimpact mechanical anomalies that would have precluded normal operation. It is likely that the pilot did not maintain airplane control and sufficient altitude to clear terrain during the turn. ## Factual narrative On May 21, 2014, about 1430 mountain daylight time, a Rockwell International S-2R, single engine, tailwheel-equipped, agricultural airplane, N702CB, registered to Boedeker Contracting Inc., of Childress, Texas, and operated by Clear Skies Aviation, LLC, of Medicine Lake, Montana, sustained substantial damage after colliding with terrain while maneuvering near Medicine Lake. The airline transport pilot, who was the sole occupant of the airplane, was not injured. Visual meteorological conditions prevailed and a flight plan was not filed for the 14 Code of Federal Regulations Part 137 aerial application flight. The local flight departed from Sher-Wood Airport, Plentywood, Montana, about 1315. The pilot reported that while maneuvering into a left banking turn following the last aerial application pass on a field, he couldn't remember what happened until he saw the ground ahead of him. The pilot tried to correct the airplane's attitude, and subsequently collided with terrain. After the airplane came to rest upright in an open field, the pilot evacuated the airplane and noted that the propeller assembly was in a feathered position. A review of the aircraft logbooks revealed that the airframe and engine underwent its most recent 100-hour inspection on March 1, 2014. At the time of the inspection, the engine had accumulated 12,833 hours since new and 58.4 hours since its hot section inspection. The airframe had accumulated a total of 6,653.8 hours of flight time. An examination of the airplane, which was conducted by a representative from the Federal Aviation Administration (FAA), revealed that the rear fuselage was buckled, and the empennage and both wings had impact damage. It was further revealed that the outboard 4 feet of the left wing had separated. The propeller assembly revealed signatures on the hub and propeller blades that were consistent with ground impact. Flight control and engine control continuity was confirmed. The fuel system revealed no anomalies other than a small amount of debris found in the filter bowl. The engine was examined at the Honeywell Product Integrity Laboratory, Phoenix, Arizona, by representatives from Honeywell, and the FAA under the supervision of the National Transportation Safety Board investigator-in-charge. The engine was disassembled. The examination of the shouldered main shaft displayed heat distress areas near four carbon bushing lands associated with the torsion shaft. The torsion shaft separated in a manor indicative of torsional overload. The torsion shaft and the shouldered main shaft overran each other, and thermal distress and rotational scoring was noted at the carbon bushing lands. According to Honeywell representatives, the separation signatures of the torsion shaft are consistent with a torsional overload due to sudden stoppage of a rotating engine at impact. In addition, both centrifugal compressor impellers and associated shrouds displayed rotational scoring through 360 degrees, which isindicative of a rotating engine at impact. Compressor shroud metal splatter was also found in the turbine section indicative of engine operation at the time of impact, although the power level could not be determined. The fuel control unit and propeller governor were further examined with no anomalies noted. The examination of the recovered engine and system components revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. ## Aircraft - Registration: [N702CB](https://openairdocs.org/deregistered/N702CB-2018-05-31), registration cancelled 2018-05-31, S/N 5085R, built 1977 (OpenAirDocs) - Reported make and model: ROCKWELL INTERNATIONAL S 2R (UNDESIGNAT) - Registry model: [Rockwell International S-2R](https://openairdocs.org/model/rockwell-international-s-2r) (registry code 7630202) (OpenAirDocs) - Registry engine: [Pratt & Whitney R1340 series](https://openairdocs.org/engine/pratt-whitney-r1340-series) (registry code 52016, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 5085R - Year built: 1977 - Airframe hours: 12833 - Engines: Garrett TPE331-5-252K 715 horsepower turbo prop - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Clear Skies Aviation, LLC - Registered owner: Clear Skies Aviation, LLC - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, March 1, 2014 - Departed: PWD, Medicine Lake, MT - Destination: PWD, Medicine Lake, MT - Airport: PWD, Sher-Wood ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 33; injuries: none; airline transport, flight instructor, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, unknown; seat: single; restraint: 4-point; flight hours: 3,900 total, 15 in this make and model, 2,100 as pilot in command, 35 in the last 90 days, 15 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: variable at 4 knots - Visibility: 10 statute miles - Temperature: 66 °F, dew point 43 °F - Altimeter: 30.12 inHg - Observed at: KISN, 36 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 20140521007489A](https://openairdocs.org/incident/20140521007489A), May 21, 2014: Rockwell International S-2R, Medicine Lake, MT, Substantial damage. Times, headings, measurements & altitudes are approximate. Aircraft N702CB, ayres S-2R, registered to & operated by clear skies aviation; took off from the… ## Docket (7 files) The files NTSB released with the investigation on November 6, 2015, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=89248. 24.5 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 827 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433711&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - NTSB Engine Examination Summary (item 2, .PDF, 66 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433712&FileExtension=.PDF&FileName=NTSB%20Engine%20Examination%20Summary-Master.PDF - Honeywell Teardown Report (165 Embedded Images) (item 3, .PDF, 22.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433713&FileExtension=.PDF&FileName=Honeywell%20Teardown%20Report%20(165%20Embedded%20Images)-Master.PDF - Airframe Logbook Entry (item 4, .PDF, 462 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433714&FileExtension=.PDF&FileName=Airframe%20Logbook%20Entry-Master.PDF - Engine Logbook Entry (item 5, .PDF, 580 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433715&FileExtension=.PDF&FileName=Engine%20Logbook%20Entry-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 6, .PDF, 137 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433716&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Master.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 7, .PDF, 108 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433717&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-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.