# NTSB CEN17LA344: Aviat A 1B, N299CA, Prairie du Chien, WI, September 9, 2017 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: September 9, 2017, 15:45 local (20:45 UTC) - Place: Prairie du Chien, WI - Coordinates: 43.021945, -91.124443 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.0219&lon=-91.1244&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report March 18, 2019 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Federal Aviation Administration, Aviat Aircraft Inc. - NTSB case key (mKey): 95982 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN17LA344 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/95982/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=95982 - Page: https://openairdocs.org/ntsb/CEN17LA344 ## Probable cause The fatigue failure of the aileron hinge bracket tubing for reasons that could not be determined based on the available evidence. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Flight control system: aileron control system](https://openairdocs.org/ntsb-findings/01022710): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause); cases with it: [Aviat A-1B, 1 case](https://openairdocs.org/ntsb-findings/01022710/cases.md?model=2210406), [All aircraft, 45 cases](https://openairdocs.org/ntsb-findings/01022710/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute: Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333) (defining event); cases with it: [Aviat A-1B, 2 cases](https://openairdocs.org/ntsb-events/333/sequence.md?model=2210406), [All aircraft, 410 cases](https://openairdocs.org/ntsb-events/333/sequence.md) ## Analysis Following the aerial photography portion of the flight, the commercial pilot climbed the airplane to 3,500 ft mean sea level and proceeded toward the destination. About 5 minutes later, he felt "light buffeting" as the airplane rolled left. He attempted to counteract the left roll by applying right control stick pressure, but the airplane continued to roll left. He input right rudder to stop the left roll and decided to return to the airport of origin, 10 nautical miles away. He used the rudder to maneuver the airplane and landed uneventfully. After parking the airplane, he moved the control stick left and right several times and the outboard end of the left aileron fell to the ground. Review of airplane maintenance records revealed that, about 9 years before the accident, the left wing tip was replaced due to "hangar rash," though there was no specific mention of damage to the left aileron. There were no other logbook entries that mentioned the left wing or left aileron. Metallurgical analysis of the aileron hinge bracket revealed two fatigue fracture origins that led to two regions of final overstress fracture. The fatigue fractures occurred under low stress over an extended period of time. No anomalies were noted in the origin regions and there was no specific evidence of bending at the fracture area. Since there was no specific evidence of bending, it could not be determined if the previous damage to the wing tip resulted in unidentified stress to the fracture area. Wing tip damage as a result of hangar rash could have resulted in residual tension in the aileron tube and precipitated the low-stress fatigue fracture; however, the severity of previous damage to the wing tip and whether the aileron was affected could not be determined. ## Factual narrative On September 9, 2017, about 1545 central daylight time, an Aviat Husky A-1B airplane, N299CA, experienced a flight control failure near Prairie du Chien, Wisconsin. The commercial rated pilot was not injured and the airplane sustained substantial damage to the left aileron. The airplane was registered to and operated by Grandview Photo Inc., under the provisions of 14 Code of Federal Regulations Part 91 as an aerial photography flight. Visual meteorological conditions prevailed at the time of the accident and no flight plan was filed. The flight departed Prairie du Chien Municipal Airport (PDC), Prairie du Chien, Wisconsin, about 1300, flew over northwest Iowa for the aerial photography portion of the flight, and was destined for La Crosse Regional Airport (LSE), La Crosse, Wisconsin. The pilot reported that he concluded the aerial photography portion of the flight, climbed the airplane to 3,500 ft mean sea level and proceeded toward LSE. About 5 minutes later he felt "light buffeting" as the airplane rolled left. He attempted to counteract the left roll by inputting right control stick pressure, but the airplane continued to roll left. He input right rudder to stop the left roll and decided to return to PDC, which was about 10 nautical miles southeast of his location. He used the rudder to maneuver the airplane to PDC and landed uneventfully. After parking the airplane, he moved the control stick left and right several times and the outboard end of the left aileron fell to the ground. The pilot and his mechanic disconnected the inboard aileron connection and removed it for examination. A review of the airplane maintenance logbooks revealed that on August 8, 2008, the left wing tip was replaced due to "hangar rash" and there was no specific mention of damage to the left aileron. There were no other logbook entries that mentioned the left wing or left aileron. The most recent airframe annual inspection was completed on January 18, 2017, at and airplane total time of 5,348 hours; the airframe had accumulated 5,177 hours since the wing tip was replaced. The aileron hinge bracket was removed and sent to the NTSB Materials Laboratory for a detailed examination. The examination revealed that the main tube exhibited a complete circumferential fracture just aft of the mounting flange (figure 1). Figure 1 – Aileron Hinge Bracket The fracture surface on the flange side was examined with a scanning electron microscope, which revealed two fatigue fracture origins that led to two regions of final overstress fracture. The fatigue fractures occurred under low stress over an extended period of time. No anomalies were noted in the origin regions. The fractures did not occur at the welds and no anomalies were noted with the welds. The examination did not find any specific evidence of bending at the fracture area. ## Aircraft - Registration: [N299CA](https://openairdocs.org/aircraft/N299CA), registered now, S/N 2294, built 2005 (OpenAirDocs) - Reported make and model: AVIAT AIRCRAFT INC A 1B - Registry model: [Aviat A-1B](https://openairdocs.org/model/aviat-a-1b) (registry code 2210406) (OpenAirDocs) - Registry engine: [Lycoming O-360 series](https://openairdocs.org/engine/lycoming-o-360-series) (registry code 41575, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 2294 - Year built: 2005 - Airframe hours: 5779 - Engines: LYCOMING O-360-A1P 180 horsepower reciprocating - Damage: Substantial damage - Flight: Business, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, January 24, 2017 - Departed: PDC, PRAIRIE DU CHIEN, WI - Destination: LSE, LA CROSSE, WI - Airport: PDC, Prairie Du Chien Muni, runway 11, 3,999 × 75 ft, asphalt - Equipment: Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 57; injuries: none; commercial, flight instructor; airplane ratings: single-engine sea, single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review April 13, 2017; seat: front; flight hours: 19,430 total, 16,000 in this make and model, 19,330 as pilot in command, 353 in the last 90 days, 115 in the last 30 days, 14 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 130° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 77 °F, dew point 52 °F - Altimeter: 30.29 inHg - Observed at: KPDC ## 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 20170909017729A](https://openairdocs.org/incident/20170909017729A), Sep 9, 2017: Aviat Aircraft Inc A-1B, Prairie Du Chie, WI, Minor damage. On 09/09/2017 pilot departed kpdc at approx 1 pm and continued photographing in Iowa. Stopped photo ops at about 1530, climed to 3,500 MSL, leveled off, and… ## Other investigations on N299CA (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 CEN26LA295](https://openairdocs.org/ntsb/CEN26LA295), Aug 17, 2026: Aviat A-1B (N299CA), Pilot Grove, MN, substantial damage, investigation ongoing ## Docket (7 files) The files NTSB released with the investigation on June 26, 2018, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=95982. 12.4 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40464505&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - FAA Inspector's Statement (item 2, .PDF, 2.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40464506&FileExtension=.PDF&FileName=FAA%20Inspector%27s%20Statement-Master.PDF - Maintenance Records (item 3, .PDF, 817 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40464507&FileExtension=.PDF&FileName=Maintenance%20Records-Master.PDF - Materials Laboratory Factual Report (item 4, .PDF, 5.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40464508&FileExtension=.PDF&FileName=Materials%20Laboratory%20Factual%20Report-Master.PDF - Photos (item 5, .PDF, 4 photos, 266 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40464509&FileExtension=.PDF&FileName=Photos-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 6, .PDF, 257 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40464510&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Master.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 7, .PDF, 120 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40464511&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.