# NTSB WPR20CA298: Cessna 208, N186GC, Whitmore, AZ, September 7, 2020 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 4 · Data collection · Final report - Date: September 7, 2020, 13:00 local (20:00 UTC) - Place: Whitmore, AZ - Coordinates: 36.256389, -113.23083 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.2564&lon=-113.2308&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - Highest injury: No injuries - Injuries: 8 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 4 - Basic report with no Prelim publish - NTSB office: Western Pacific Region - Parties: FAA - FSDO - NTSB case key (mKey): 101931 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR20CA298 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101931/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=101931 - Page: https://openairdocs.org/ntsb/WPR20CA298 ## Probable cause A loss of directional control during landing due to a flat main landing gear tire, which resulted in a lateral runway excursion and impact with terrain. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: tube](https://openairdocs.org/ntsb-findings/01023245): Aircraft › Aircraft systems · Unknown/Not determined (probable cause); cases with it: [Cessna 208B, 1 case](https://openairdocs.org/ntsb-findings/01023245/cases.md?model=2073701), [All aircraft, 19 cases](https://openairdocs.org/ntsb-findings/01023245/cases.md) - [Performance/control parameters: directional control](https://openairdocs.org/ntsb-findings/01062020): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible (probable cause); cases with it: [Cessna 208B, 8 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md?model=2073701), [All aircraft, 3,958 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-landing roll: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Cessna 208B, 1 case](https://openairdocs.org/ntsb-events/330/sequence.md?model=2073701), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) - [Landing-landing roll: Unknown or undetermined](https://openairdocs.org/ntsb-events/000); cases with it: [Cessna 208B, 6 cases](https://openairdocs.org/ntsb-events/000/sequence.md?model=2073701), [All aircraft, 1,703 cases](https://openairdocs.org/ntsb-events/000/sequence.md) - [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230); cases with it: [Cessna 208B, 7 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=2073701), [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: [Cessna 208B, 8 cases](https://openairdocs.org/ntsb-events/300/sequence.md?model=2073701), [All aircraft, 3,643 cases](https://openairdocs.org/ntsb-events/300/sequence.md) - [Landing-landing roll: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Cessna 208B, 20 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=2073701), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis **This report was modified on December 5, 2024. Please see the docket for this accident to view the original report.** The pilot reported that, during the landing ground roll, the airplane started to veer left. He applied right rudder input, but the airplane continued to “drag” left. As the pilot repositioned his feet to apply the brakes, the airplane “turned harder to the left,” exited the runway, and impacted terrain. The right wing was substantially damaged. The pilot thought that “a left main tire malfunction on or before landing” had occurred. An examination of the left wheel and tire assembly (by the Federal Aviation Administration) found that the valve stem to the tire inner tube had completely sheared off and was located inside the tire. No other damage to the inner tube was noted, and no other anomalies were observed within the assembly. The operator’s director of maintenance reported no preimpact mechanical malfunctions or failures that would have precluded normal operation. A video recording of the accident landing (taken by a passenger in the first row of passenger seats) indicated that, based on the sound recorded, the left main landing gear tire became flat immediately after main gear touchdown. The left flat tire would have increased the drag between the tire and the runway surface, resulting in a left-turning tendency and a loss of directional control. In addition, a photograph taken during the on-scene investigation showed a double track on the runway starting near the location where the left main tire touched down. The double track was likely caused by the rubber in the left and right sidewalls of the tire contacting the runway after the center of the tire deflated. The left main landing gear tire was installed on the airplane 3 days before the accident. The tire could have become flat if it had been improperly installed or had a material defect. It is also possible that the tire became flat because it hit something not heard or seen on the video of the landing. In addition, another photograph taken during the on-scene investigation showed that the valve stem of the tire inner tube was sheared, indicating that the tire could have become flat because the valve (within the valve stem) had failed. The failure mode for the left main landing gear tire could not be determined based on the available evidence. Nevertheless, the evidence was sufficient to show that the reason for the airplane’s loss of lateral directional control was the flat left main tire. ## Aircraft - Registration: [N186GC](https://openairdocs.org/deregistered/N186GC-2023-04-07), registration cancelled 2023-04-07, S/N 208B2161, built 2009 (OpenAirDocs) - Reported make and model: Cessna 208 (B) - Registry model: [Cessna 208B](https://openairdocs.org/model/cessna-208b) (registry code 2073701) (OpenAirDocs) - Registry engine: [Pratt & Whitney Canada PT6A-114A](https://openairdocs.org/engine/pratt-whitney-canada-pt6a-114a) (registry code 52257, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 208B2161 - Year built: 2009 - Airframe hours: 8044.3 - Engines: Pratt & Whitney Canada PT6A-114A 675 horsepower turbo prop - Damage: Substantial damage - Flight: Other work use, Part 135 - Operator: Grand Canyon Airlines - Registered owner: Zuni Llc - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, August 22, 2020, 35.8 hours before - Departed: KBVU, Boulder City, NV - Destination: Same as departure - Airport: 1Z1, Grand Canyon Bar Ten Airstrip, runway 34, 4,600 × 40 ft, asphalt - Equipment: Electronic primary flight display, Angle of attack indicator, Onboard weather, ADS-B, Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 57; injuries: none; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review August 25, 2020; seat: left; restraint: 5-point; flight hours: 1,460 total, 600 in this make and model, 1,210 as pilot in command, 216 in the last 90 days, 70 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 350° at 6 knots, gusting 14 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 102 °F, dew point 32 °F - Altimeter: 30.02 inHg - Observed at: KAZC, 43 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 20200907014369A](https://openairdocs.org/incident/20200907014369A), Sep 7, 2020: Cessna 208B, Whitemore, AZ, Substantial damage. On 9/7/2020 at about 1249 AZ time, N186GC went off the runway at Grand Canyon bar ten airport in whitmore, AZ. PIC duty on at 0520 that am and it was his 4th… ## Docket (10 files) The files NTSB released with the investigation on July 12, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=101931. 12.5 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 2.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11416631&FileExtension=pdf&FileName=6120%20298_Redacted-Rel.pdf - FAA principal maintenance inspector's statement (item 2, PDF, 1 page, 10 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11416995&FileExtension=pdf&FileName=FAA%20Principal%20Maintenance%20Inpsector%20Statement-Rel.pdf - Dom record of maintenance (item 3, PDF, 1 page, 93 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11486441&FileExtension=pdf&FileName=DOM%20RECORD%20OF%20CONVERSATION-Rel.pdf - Accident photo (item 4, PDF, 2 pages, 227 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11416321&FileExtension=pdf&FileName=Accident%20Photo%20298-Rel.pdf - Petition for reconsideration (item 5, PDF, 5 pages, 4 photos, 7.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18082300&FileExtension=pdf&FileName=Whitmore,%20Arizona,%20petition_Redacted-Rel.pdf - Response to petition for reconsideration (item 6, PDF, 6 pages, 2 photos, 478 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18082738&FileExtension=pdf&FileName=FINAL%20PFR%20response%20Whitmore,%20Arizona_Redacted-Rel.pdf - Original final report (item 7, PDF, 6 pages, 761 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18083069&FileExtension=pdf&FileName=Original%20final%20report-Rel.pdf - Revised final report (item 8, PDF, 6 pages, 761 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18106831&FileExtension=pdf&FileName=Revised%20final%20report-Rel.pdf - Onboard image recorder - specialist's factual report (item 9, PDF, 3 pages, 99 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18087567&FileExtension=pdf&FileName=wpr20ca29%20onboard%20factual_4-final-Rel.pdf - Revised final report with changes tracked (item 10, PDF, 6 pages, 227 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18087446&FileExtension=pdf&FileName=Revised%20final%20report%20with%20changes%20tracked-Rel.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.