# NTSB WPR11LA412: Wheeler Vans RV-6A, N642DW, Albany, OR, August 28, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 28, 2011, 13:45 local (20:45 UTC) - Place: Albany, OR - Coordinates: 44.656944, -123.05278 - Nearby events: https://openairdocs.org/map.md?lat=44.6569&lon=-123.0528&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-climb to cruise: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report January 31, 2013 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 81618 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR11LA412 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/81618/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=81618 - Page: https://openairdocs.org/ntsb/WPR11LA412 ## Probable cause The in-flight separation of a propeller blade due to fatigue. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Propeller system: propeller hub section](https://openairdocs.org/ntsb-findings/01046114): Aircraft › Aircraft propeller/rotor · Fatigue/wear/corrosion (probable cause); cases with it: [Wheeler Dean S VANS RV-6A, 1 case](https://openairdocs.org/ntsb-findings/01046114/cases.md?model=05627BE), [All aircraft, 13 cases](https://openairdocs.org/ntsb-findings/01046114/cases.md) - [Maintenance: repair](https://openairdocs.org/ntsb-findings/02062015): Personnel issues › Task performance · Maintenance personnel; cases with it: [Wheeler Dean S VANS RV-6A, 1 case](https://openairdocs.org/ntsb-findings/02062015/cases.md?model=05627BE), [All aircraft, 99 cases](https://openairdocs.org/ntsb-findings/02062015/cases.md) - [Maintenance/inspections](https://openairdocs.org/ntsb-findings/01010500): Aircraft › Aircraft handling/service · Incorrect service/maintenance; cases with it: [Wheeler Dean S VANS RV-6A, 1 case](https://openairdocs.org/ntsb-findings/01010500/cases.md?model=05627BE), [All aircraft, 103 cases](https://openairdocs.org/ntsb-findings/01010500/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Prior to flight: Aircraft maintenance event](https://openairdocs.org/ntsb-events/040); cases with it: [Wheeler Dean S VANS RV-6A, 1 case](https://openairdocs.org/ntsb-events/040/sequence.md?model=05627BE), [All aircraft, 484 cases](https://openairdocs.org/ntsb-events/040/sequence.md) - [Enroute-climb to cruise: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) (defining event); cases with it: [Wheeler Dean S VANS RV-6A, 1 case](https://openairdocs.org/ntsb-events/338/sequence.md?model=05627BE), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) - [Landing: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Wheeler Dean S VANS RV-6A, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=05627BE), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The pilot reported that a few minutes after takeoff, he heard a loud noise and felt a vibration when an aluminum propeller blade separated from the airplane. The pilot then made a forced landing on a grass field north of the departure airport. The MT-Propeller two-bladed propeller hub, separated blade, and fracture surfaces were examined. The examination revealed finely spaced striations consistent with high-cycle fatigue. The hub wall had fatigue cracks initiating from shallow oxidized pits. Evidence of rework or repair was found on the hub blade bore. The propeller logbook reported that the hub was repaired and inspected by a repair station and reinstalled by the pilot/owner 3 days before the accident flight. ## Factual narrative On August 28, 2011, about 1345 Pacific daylight time, a Wheeler Vans RV-6A, N642DW, experienced the in-flight separation of a propeller blade during climb from the Albany Municipal Airport (S12), Albany, Oregon. All engine power was lost, and the pilot made a forced landing on a grass field north of the departure airport. The airplane was substantially damaged during the propeller blade separation event. The experimental airplane was built by the pilot, and it was operated under the provisions of 14 Code of Federal Regulations Part 91. Neither the private pilot nor passenger were injured during the personal flight. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated from S12 about 1341. The pilot reported that a few minutes after takeoff he heard a loud noise and felt a vibration when a propeller blade separated from the airplane. The pilot stated that the propeller assembly had undergone maintenance by its manufacturer on three occasions. These occasions were prompted by the pilot's observation of hub grease seeping onto the shank portion of the blades. Having observed this leakage, the pilot removed the propeller and hub assembly and returned it to the manufacturer for inspection and repair. The manufacturer reportedly performed maintenance and returned the assembly to the pilot who then reinstalled it on his airplane. The propeller logbook reported that the hub was repaired and inspected by a repair station and reinstalled by the pilot/owner 3 days prior to the accident flight. The pilot reported that the propeller had 309.1 hours and the replacement hub had 114.2 hours total time. The examination of the airplane revealed wrinkles in the upper surface of both elevators, and sections of the firewall and engine cowling were damaged. A propeller blade and a section of the propeller hub separated from the engine. The separated blade and hub section was recovered to the grass field where the aircraft subsequently landed. The MT-Propeller two bladed propeller hub serial no. 100854, and the separated propeller blade model 183-402, serial no. D-030, were sent to the National Transportation Safety Board’s (NTSB) Materials Laboratory for examination. According to the NTSB Materials Laboratory Report, the inspection revealed that the propeller hub fractured near the root of one of the propeller blades. Radial lines and chevron marks in the overstress region were used to trace the crack back to its origin, located approximately 45° from the forward face of the hub toward the direction of rotation. Fatigue crack propagation was found near the origin. The fracture surface was examined using a scanning electron microscope (SEM). Finely spaced striations consistent with high-cycle fatigue were found near the origin. SEM examination along the hub wall indicated that the fatigue cracks were initiating at shallow oxidized pits on the inner surface. The hub blade bore had a golden color and exhibited circumferentialsanding lines. The area around the bore, such as the seat for the preload ring had a gray appearance and exhibited a line pattern typical of machining marks. The difference in color and the sanding lines in the bore were consistent with a repair of the hub blade bore. (Refer to the attached NTSB Materials Lab Factual Report.) ## Aircraft - Registration: [N642DW](https://openairdocs.org/deregistered/N642DW-2017-06-19), registration cancelled 2017-06-19, S/N 22286, built 2009 (OpenAirDocs) - Reported make and model: WHEELER VANS RV-6A - Registry model: [Wheeler Dean S VANS RV-6A](https://openairdocs.org/model/wheeler-dean-s-vans-rv-6a) (registry code 05627BE) (OpenAirDocs) - Registry engine: [Superior IO-360 series](https://openairdocs.org/engine/superior-io-360-series) (registry code 59251, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 22286 - Airframe hours: 309 - Engines: SUPERIOR IO-360 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Wheeler Dean S - Registered owner: Wheeler Dean S - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, January 5, 2011, 114 hours before - Departed: S12, Albany, OR - Destination: S12, Albany, OR - Airport: Kaiser's Strip, runway 30, 1,600 × 20 ft, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 70; injuries: none; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; seat: left; flight hours: 908 total, 297 in this make and model, 830 as pilot in command, 64 in the last 90 days, 21 in the last 30 days, 6 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F ## 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 20110828019649A](https://openairdocs.org/incident/20110828019649A), Aug 28, 2011: Wheeler Dean S VANS RV-6A, Albany, OR, Substantial damage. On August 28, 2011, about 1345 pacific daylight time, a Wheeler vans RV-6A, N642DW, experienced in-flight separation of a propeller blade during climb out from… ## Docket (3 files) The files NTSB released with the investigation on November 30, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=81618. 9.1 MB in all. - Materials Laboratory 15 - Factual Report 12-117 (with 9 embedded images) (item 1, .PDF, 9 photos, 2.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40380155&FileExtension=.PDF&FileName=Materials%20Laboratory%2015%20-%20Factual%20Report%2012-117%20(with%209%20embedded%20images)-Master.PDF - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 2, .PDF, 4.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40382447&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Photo 1-Propeller Log Book (item 3, .PDF, 2.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40382260&FileExtension=.PDF&FileName=Photo%201-Propeller%20Log%20Book-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.