# NTSB CEN12CA607: North American AT-6F, N244GR, Council Bluffs, IA, August 31, 2012 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: August 31, 2012, 07:40 local (12:40 UTC) - Place: Council Bluffs, IA - Coordinates: 41.256111, -95.755279 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.2561&lon=-95.7553&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report December 19, 2012 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA Des Moines FSDO - NTSB case key (mKey): 84937 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN12CA607 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/84937/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=84937 - Page: https://openairdocs.org/ntsb/CEN12CA607 ## Probable cause An unlocking of the excessively worn tailwheel lock mechanism, which resulted in a loss of directional control during landing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: nose/tail landing gear](https://openairdocs.org/ntsb-findings/01023220): Aircraft › Aircraft systems · Damaged/degraded (probable cause); cases with it: [All aircraft, 185 cases](https://openairdocs.org/ntsb-findings/01023220/cases.md) - [Landing gear system: landing gear steering system](https://openairdocs.org/ntsb-findings/01023250): Aircraft › Aircraft systems · Inoperative (probable cause); cases with it: [All aircraft, 32 cases](https://openairdocs.org/ntsb-findings/01023250/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Takeoff-rejected takeoff: Miscellaneous/other](https://openairdocs.org/ntsb-events/900); cases with it: [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md) - [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230) (defining event); cases with it: [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) - [Landing-landing roll: Runway excursion](https://openairdocs.org/ntsb-events/300); cases with it: [All aircraft, 3,643 cases](https://openairdocs.org/ntsb-events/300/sequence.md) - [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094); cases with it: [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis Immediately after liftoff, the flight instructor simulated an engine failure, and the pilot executed a rejected takeoff, landing on the remaining runway. When the tailwheel contacted the runway, it began to "shimmy violently and disengaged the steering pin." The airplane veered to the left, and the pilot was unable to stop the veer using the right rudder and brake. The airplane exited the left side of the runway while moving sideways to the right. The right main landing gear collapsed, resulting in substantial damage to the right wing. An examination of the tailwheel mechanism showed excessive wear in both the locking collar hole and the drag links in the tailwheel assembly. It was likely that the locking pin had become retracted from the locking collar on the tailwheel at some time during the takeoff or during the landing. Both pilots stated that they had locked the mechanism before takeoff and had good directional control of the airplane during the takeoff run. ## Factual narrative Immediately after liftoff the flight instructor simulated an engine failure and the pilot executed a rejected takeoff, landing on the runway remaining. When the tailwheel contacted the runway it began to "shimmy violently and disengaged the steering pin." The airplane veered to the left and the pilot was unable to stop the veer using right rudder and brake. The airplane exited the left side of the runway moving sideways to the right. The right main landing gear collapsed causing substantial damage to the right wing. An examination of the tailwheel mechanism showed excessive wear in both the locking collar hole and the drag links in the tailwheel assembly. Both pilots stated that they had locked the mechanism before takeoff and had good directional control of the airplane during the takeoff run. ## Aircraft - Registration: N244GR (not matched to a registry record) - Reported make and model: NORTH AMERICAN AT-6F - Category: Airplane - Serial number: 121-42642 - Airframe hours: 2800 - Engines: P&W R1340-AN1 600 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 23, 2012 - Departed: CBF, Council Bluffs, IA - Destination: CBF, Council Bluffs, IA - Airport: CBF, Council Bluffs Municipal, runway 18, 5,500 × 100 ft, concrete ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 38; injuries: none; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, without waivers/limitations; last flight review March 12, 2011; seat: front; flight hours: 735 total, 4 in this make and model, 670 as pilot in command, 40 in the last 90 days, 9 in the last 30 days, 1 in the last 24 hours - Flight instructor; age 58; injuries: none; airline transport, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: with waivers/limitations; seat: rear; flight hours: 1 total, 1 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 120° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 68 °F, dew point 57 °F - Altimeter: 30.01 inHg - Observed at: KCBF ## 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 20120831022329A](https://openairdocs.org/incident/20120831022329A), Aug 31, 2012: North American AT-6F, Council Bluffs, IA, Substantial damage. The day of the accident the wind was calm and the prevailing weather was VMC. The PIC was flying the aircraft from the front seat and performed the takeoff.… ## Docket (4 files) The files NTSB released with the investigation on October 25, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=84937. 3.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 674 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40378083&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Record of Conversation (item 2, .PDF, 51 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40379027&FileExtension=.PDF&FileName=Record%20of%20Conversation-Master.PDF - Photo 1 (item 3, .PDF, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40378086&FileExtension=.PDF&FileName=Photo%201-Master.PDF - Photo 2 (item 4, .PDF, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40378092&FileExtension=.PDF&FileName=Photo%202-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.