# NTSB CEN11LA077: Halbrook Rans S-6S, N280JH, St. Cloud, MN, November 17, 2010 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: November 17, 2010, 16:30 local (22:30 UTC) - Place: St. Cloud, MN - Coordinates: 45.546665, -94.059997 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=45.5467&lon=-94.0600&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach-VFR pattern final: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report December 27, 2011 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Federal Aviation Administration - Minneapolis FSDO - NTSB case key (mKey): 77838 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN11LA077 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/77838/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=77838 - Page: https://openairdocs.org/ntsb/CEN11LA077 ## Probable cause The airplane kit manufacturer’s recommended use of an improper nut type for securing the door hinge. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Doors: passenger/crew doors](https://openairdocs.org/ntsb-findings/01035210): Aircraft › Aircraft structures · Malfunction (probable cause); cases with it: [Halbrook Jim RANS S6S, 1 case](https://openairdocs.org/ntsb-findings/01035210/cases.md?model=05901LG), [All aircraft, 86 cases](https://openairdocs.org/ntsb-findings/01035210/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Approach-VFR pattern final: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) (defining event); cases with it: [Halbrook Jim RANS S6S, 1 case](https://openairdocs.org/ntsb-events/338/sequence.md?model=05901LG), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) ## Analysis The pilot reported that while practicing touch-and-go landings he noticed that the nut from the forward door hinge of the left cabin door was missing. He decided to make a full stop landing to inspect further. During final approach, the door separated from the fuselage; the pilot was able to complete the landing without further incident. A postaccident examination confirmed that the forward door hinge bolt/nut assembly had backed-off during flight, which precipitated the door separating from the airplane. The airplane kit manufacturer guidance indicated that a shear stop nut was to be used in the gull-wing (upward opening) door hinge assemblies. However, the Federal Aviation Administration (FAA) advises (in Advisory Circular 43.13-1B) that self-locking nuts, such as the type used on the accident airplane door, are not recommended for use on parts subject to rotation. The FAA further advises that the use of self-locking castellated nuts with cotter pins or lockwire is a more suitable method to secure rotating parts. According to the kit manufacturer, the accident flight was the first documented instance where a door separated during flight. ## Factual narrative On November 17, 2010, about 1630 central standard time, an experimental amateur-built Halbrook Rans S-6S airplane, N280JH, was substantially damaged when the left cabin door separated from the fuselage while on final approach to runway 31 at the St. Cloud Regional Airport (KSTC), near St. Cloud, Minnesota. The pilot and his flight instructor were not injured. The airplane was registered to Airflight LLC, and operated by a commercial pilot under the provisions of 14 Code of Federal Regulations Part 91. Day visual meteorological conditions prevailed for the flight, which was operated without a flight plan. The local flight departed KSTC at 1530. The pilot reported that while practicing touch-and-go landings he noticed that the nut from the forward door hinge of the left cabin door was missing. He decided to make a full stop landing to inspect further. While established on final approach, about 1/2 mile from the runway threshold, the door separated from the fuselage. The pilot was able to complete the landing without further incident. A postaccident investigation revealed that the door had impacted the left wing, aft fuselage, left elevator, and the left side of the rudder resulting in substantial damage. Further inspection confirmed that the forward door hinge bolt/nut assembly had backed-off during flight, which precipitated the door separating from the airplane. The airplane’s last condition inspection was completed on April 23, 2010. The airplane had accumulated 219 hours since new at the time of the accident. The builder guidance provided by the kit manufacturer (Rans Aircraft), including the parts listing for the airplane, indicated that a 3/16-inch shear stop nut (AN3641032A) was used in the door hinge assemblies. The gull-wing (upward opening) doors are designed to be easily removed from the fuselage for open-cockpit flight. The same door and hinge design was also incorporated in other Rans models. According to the kit manufacturer, the accident flight was the first documented instance where a door has separated during flight. According to Federal Aviation Administration Advisory Circular 43.13-1B (Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair), the use of self-locking nuts, such as the type used on the accident airplane door, is not recommended for parts subject to rotation. Alternatively, the use of self-locking castellated nuts with cotter pins or lockwire is listed as a suitable method to secure rotating parts. ## Aircraft - Registration: [N280JH](https://openairdocs.org/aircraft/N280JH), registered now, S/N 12051716, built 2006 (OpenAirDocs) - Reported make and model: Halbrook Rans S-6S - Registry model: [Halbrook Jim RANS S6S](https://openairdocs.org/model/halbrook-jim-rans-s6s) (registry code 05901LG) (OpenAirDocs) - Registry engine: [Rotax 912S series](https://openairdocs.org/engine/rotax-912s-series) (registry code 55570, 4 cycle) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 12051716 - Airframe hours: 219 - Engines: Rotax 912 ULS 100 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Airflight, LLC. - Registered owner: Airflight, LLC. - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, April 23, 2010 - Departed: KSTC, St. Cloud, MN - Destination: KSTC, St. Cloud, MN - Airport: KSTC, St. Cloud Regional Airport, runway 31, 7,000 × 150 ft, concrete ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 23; injuries: none; commercial; airplane ratings: single-engine sea, multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review June 24, 2009; seat: left; flight hours: 399 total, 163 in this make and model, 379 as pilot in command, 76 in the last 90 days, 18 in the last 30 days, 1 in the last 24 hours - Flight instructor; age 24; injuries: none; commercial, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review March 2, 2009; seat: right; flight hours: 1,024 total, 3 in this make and model, 921 as pilot in command, 45 in the last 90 days, 22 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 320° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: 2,600 ft overcast - Temperature: 32 °F, dew point 23 °F - Altimeter: 30.22 inHg - Observed at: KSTC, 1 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 20101117052529A](https://openairdocs.org/incident/20101117052529A), Nov 17, 2010: Halbrook Ji RANS S6S, St. Cloud, MN, Substantial damage. While on approch to land the pilot stated that the left door departed the aircraft and damaged the left wing, fuselage, left elevator and rudder. The pilot was… ## Docket (5 files) The files NTSB released with the investigation on November 18, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=77838. 2.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 872 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40348063&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Rans S-6S Door Assembly Drawing and Part Listing (item 2, .PDF, 961 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40348064&FileExtension=.PDF&FileName=Rans%20S-6S%20Door%20Assembly%20Drawing%20and%20Part%20Listing-Master.PDF - NTSB Letter Sent to Rans Aircraft (Ed Schwab) Concerning Door Assembly Hardware (item 3, .PDF, 168 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40348066&FileExtension=.PDF&FileName=NTSB%20Letter%20Sent%20to%20Rans%20Aircraft%20(Ed%20Schwab)%20Concerning%20Door%20Assembly%20Hardware-Redacted.PDF - Summary of Safety Actions Pursued (item 4, .PDF, 74 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358255&FileExtension=.PDF&FileName=Summary%20of%20Safety%20Actions%20Pursued-Master.PDF - Weather Reports (item 5, .PDF, 39 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358256&FileExtension=.PDF&FileName=Weather%20Reports-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.