# NTSB WPR16LA155: Beech C 99, N234AV, Spanish Fork, UT, August 2, 2016 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 1, 2016, 18:50 local (Aug 2, 2016, 00:50 UTC) - Place: Spanish Fork, UT - Coordinates: 40.018333, -111.48278 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=40.0183&lon=-111.4828&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-climb to cruise: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report September 11, 2018 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: FAA Salt Lake FSDO - NTSB case key (mKey): 93734 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR16LA155 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/93734/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=93734 - Page: https://openairdocs.org/ntsb/WPR16LA155 ## Probable cause An in-flight collision with power lines. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Attention/monitoring: monitoring environment](https://openairdocs.org/ntsb-findings/02021545): Personnel issues › Psychological · Pilot (probable cause); cases with it: [Beech C-99, 1 case](https://openairdocs.org/ntsb-findings/02021545/cases.md?model=1154006), [All aircraft, 809 cases](https://openairdocs.org/ntsb-findings/02021545/cases.md) - [Object/animal/substance: wire](https://openairdocs.org/ntsb-findings/03022032): Environmental issues › Physical environment · Effect on operation; cases with it: [Beech C-99, 1 case](https://openairdocs.org/ntsb-findings/03022032/cases.md?model=1154006), [All aircraft, 588 cases](https://openairdocs.org/ntsb-findings/03022032/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-climb to cruise: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) (defining event); cases with it: [Beech C-99, 1 case](https://openairdocs.org/ntsb-events/900/sequence.md?model=1154006), [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md) ## Analysis The commercial pilot of the scheduled cargo flight reported that, during cruise flight about 8,000 ft indicated altitude, he heard a small impact noise and believed that the airplane was struck by a bird. There was no loss of directional control, change in control configuration, or impact shudder. He continued the flight and subsequently landed without further incident. After exiting the airplane, the pilot noticed that about 12 inches of the top of the vertical stabilizer was missing, and that there was substantial damage to the rudder. The separated top of the vertical stabilizer section was not recovered. The fracture surface of the upper section of the remaining vertical stabilizer was in a nearly horizontal plane. The skin was deformed adjacent to the fracture into curled rolls turning downward and aft. Some areas were crushed, consistent with the vertical stabilizer moving forward relative to another object. Sliding contact marks were observed at the leading edges, vertical spars, and deformed faces of the skin panel adjacent to the fracture. No evidence of any biological or manufactured foreign material transfer was observed associated with any of the fracture surfaces either visually or under optical magnification. Closer examination identified deposits of particles consistent with aluminum alloy 2024 and similar metallic element peaks. Other particles had spectra consistent with a low alloy steel, stainless steel, brass, and a nickel-base alloy with iron and chromium. The curling deformation to the skin and the deformation through the airplane structure was consistent with contact with a stationary object, such as a suspended cable. Given the diameter of the impact deformation and the materials found, it is likely that the airplane impacted overhead power transmission lines during a portion of the flight that was conducted at an altitude much lower than reported. ## Factual narrative On August 1, 2016, about 1850 mountain daylight time, a twin-engine turboprop Beech C-99 airplane, N234AV, collided with an object while in-flight near Spanish Fork, Utah. The commercial pilot was not injured. The airplane sustained substantial damage to the vertical stabilizer and rudder. The airplane was registered to UAS Trans Services and operated as AMF1843 by Ameriflight, LLC as a Title 14 Code of Federal Regulations Part 135 scheduled cargo flight. Visual meteorological conditions were reported at the time of the accident, and company flight following procedures were in effect. The flight originated from Carbon County Regional Airport (PUC), Price, Utah about 1830 and was destined for Salt Lake City, Utah. The pilot reported that while about 8,000 - 8,500 ft indicated altitude, he heard a small impact noise and believed that the airplane was struck by a bird. There was no loss of directional control, change in control configuration, or impact shudder. He continued the flight and subsequently landed without further incident. After exiting the airplane, the pilot noticed about 12 inches of the top of the vertical stabilizer was missing, and there was substantial damage to the rudder. The separated top of the vertical stabilizer section was not recovered. A section of the remaining upper area of the vertical stabilizer, rudder and the rudder trim were removed from the airplane and sent to the National Transportation Safety Board Materials Laboratory, Washington DC for examination. The materials engineer reported that the pieces were fractured in a nearly horizontal plane at the upper ends of the submitted pieces. The skin on the vertical stabilizer and rudder were deformed adjacent to the fracture into curled rolls turning downward and aft. Some areas were crushed consistent with the vertical stabilizer moving forward relative to another object. Sliding contact marks were observed at the leading edges, vertical spars, and deformed faces of the skin panel adjacent to the fracture. No evidence of any biological or manufactured foreign material transfer was observed associated with any of the fracture surfaces as observed visually and under optical magnification. Closer examination using a scanning electron microscope (SEM) with energy dispersive x-ray spectroscopy (EDS) identified deposits of particles consistent with aluminum alloy 2024, and similar metallic element peaks. Other particles had spectra consistent with a low alloy steel, stainless steel, brass, and a nickel-base alloy with iron and chromium. ## Aircraft - Registration: [N234AV](https://openairdocs.org/deregistered/N234AV-2019-12-03), registration cancelled 2019-12-03, S/N U-234, built 1986 (OpenAirDocs) - Reported make and model: BEECH C 99 (NO SERIES) - Registry model: [Beech C-99](https://openairdocs.org/model/beech-c-99) (registry code 1154006) (OpenAirDocs) - Registry engine: [Pratt & Whitney Canada PT6A-60A](https://openairdocs.org/engine/pratt-whitney-canada-pt6a-60a) (registry code 52043, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: U-234 - Year built: 1986 - Airframe hours: 28737.5 - Engines: Pratt & Whitney PT6A-60 750 horsepower turbo prop; Pratt & Whitney PT6A-36 750 horsepower turbo prop - Damage: Substantial damage - Flight: Part 135 - Operator: Ameriflight Inc - Registered owner: Uas Transervices Inc - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, July 5, 2016, 34 hours before - Departed: PUC, PRICE, UT - Destination: SLC, Salt Lake City, UT - Flight plan: Company VFR - Equipment: Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 22; 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 April 25, 2016; seat: left; restraint: 3-point; flight hours: 1,434 total, 177 in this make and model, 845 as pilot in command, 177 in the last 90 days, 24 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 20° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: 14,000 ft broken - Temperature: 88 °F, dew point 46 °F - Altimeter: 30.03 inHg - Observed at: KPVU, 16 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 20160801007239A](https://openairdocs.org/incident/20160801007239A), Aug 1, 2016: Beech C-99, Thistle, UT, Substantial damage. While in cruise flight at an altitude of 8500 MSL near the junction of highway 6 and highway 89 in spanish fork canyon, Utah the pilot reported seeing a dark… ## Docket (3 files) The files NTSB released with the investigation on May 10, 2018, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=93734. 3.0 MB in all. - Materials Laboratory Factual Report 17-004 (item 1, .PDF, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40463112&FileExtension=.PDF&FileName=Materials%20Laboratory%20Factual%20Report%2017-004-Master.PDF - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 2, .PDF, 874 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40463110&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Accident Photos (item 3, .PDF, 2 photos, 255 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40463111&FileExtension=.PDF&FileName=Accident%20Photos-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.