# NTSB WPR20LA122: Buckman Bucks Special, N9065F, Prescott, WA, April 9, 2020 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: April 9, 2020, 11:30 local (18:30 UTC) - Place: Prescott, WA - Coordinates: 46.297625, -118.29348 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=46.2976&lon=-118.2935&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - SAIBs cited in the narratives: [SAIB CE-09-35](https://openairdocs.org/saib/CE-09-35) (OpenAirDocs) - NTSB case key (mKey): 101169 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR20LA122 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101169/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=101169 - Page: https://openairdocs.org/ntsb/WPR20LA122 ## Probable cause Diminished engine performance due to carburetor icing conditions and multiple mechanical anomalies that did not allow for the airplane to attain adequate airspeed during takeoff from a planted field and failure to maintain clearance from obstructions. Contributing to the accident was improper maintenance. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Power plant: air intake](https://openairdocs.org/ntsb-findings/01057160): Aircraft › Aircraft power plant · Incorrect service/maintenance (probable cause); cases with it: [Buckman Donald F BUCKS SPECIAL, 1 case](https://openairdocs.org/ntsb-findings/01057160/cases.md?model=05630BV), [All aircraft, 50 cases](https://openairdocs.org/ntsb-findings/01057160/cases.md) - [Engine fuel and control: fuel distribution](https://openairdocs.org/ntsb-findings/01057310): Aircraft › Aircraft power plant · Incorrect service/maintenance (probable cause); cases with it: [Buckman Donald F BUCKS SPECIAL, 1 case](https://openairdocs.org/ntsb-findings/01057310/cases.md?model=05630BV), [All aircraft, 55 cases](https://openairdocs.org/ntsb-findings/01057310/cases.md) - [Temp/humidity/pressure: conducive to carburetor icing](https://openairdocs.org/ntsb-findings/03031030): Environmental issues › Conditions/weather/phenomena · Effect on equipment (probable cause); cases with it: [Buckman Donald F BUCKS SPECIAL, 1 case](https://openairdocs.org/ntsb-findings/03031030/cases.md?model=05630BV), [All aircraft, 435 cases](https://openairdocs.org/ntsb-findings/03031030/cases.md) - [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Buckman Donald F BUCKS SPECIAL, 1 case](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=05630BV), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md) - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Maintenance personnel; cases with it: [Buckman Donald F BUCKS SPECIAL, 1 case](https://openairdocs.org/ntsb-findings/02062010/cases.md?model=05630BV), [All aircraft, 320 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md) - [Performance/control parameters: altitude](https://openairdocs.org/ntsb-findings/01062012): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Buckman Donald F BUCKS SPECIAL, 1 case](https://openairdocs.org/ntsb-findings/01062012/cases.md?model=05630BV), [All aircraft, 1,310 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md) - [Runway/land/takeoff/taxi surface: soft surface](https://openairdocs.org/ntsb-findings/03023020): Environmental issues › Physical environment · Effect on operation; cases with it: [Buckman Donald F BUCKS SPECIAL, 1 case](https://openairdocs.org/ntsb-findings/03023020/cases.md?model=05630BV), [All aircraft, 264 cases](https://openairdocs.org/ntsb-findings/03023020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Buckman Donald F BUCKS SPECIAL, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=05630BV), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Initial climb: Loss of control in flight](https://openairdocs.org/ntsb-events/240); cases with it: [Buckman Donald F BUCKS SPECIAL, 1 case](https://openairdocs.org/ntsb-events/240/sequence.md?model=05630BV), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) ## Analysis The pilot of the tailwheel-equipped airplane reported that, during takeoff from a planted field and shortly after becoming airborne, the airplane was not able to climb. He then initiated a left turn to avoid trees and powerlines at the end of the strip. The left wing tip subsequently contacted the ground, resulting in a hard landing, noseover, and substantial damage to the wings and vertical stabilizer. The pilot reported a lack of performance that would not allow the airplane to gain altitude. It is likely that the airplane did not reach the normal takeoff speed due to the drag on the landing gear from the planted field and departed with insufficient airspeed for lift. A postaccident examination of the engine revealed several anomalies. A portion of a fuel line was found looped around an engine mount, partially collapsing the line due to the sharp bend. This partially collapsed fuel line likely affected the fuel flow and operation of the fuel pump. A soft fuel pump line was attached to the impulse side of the fuel pump. The fuel line likely absorbed the pneumatic impulse from the crankcase, and it also may have affected the overall performance of the fuel pump. The air induction filter pleats were dirty, gray in color, and absent of the protective filter oil. A dirty air filter likely affected the fuel-air mixture to the cylinders. The carburetor venting tubes were modified with a tube that ran down the engine mount towards the bottom of the engine firewall. The venting tube was not placed in a neutral pressure zone, which likely affected the operation of the carburetors. The beginning of the exhaust expansion chamber had a sharp 90° bend that would have likely restricted exhaust flow and the pressure pulse from the exhaust. The restriction in the exhaust combined with the other anomalies found during the postaccident examination would likely negatively affect the overall performance of the engine. The engine was test run and no anomalies were observed; however, the engine was not tested on a dynamometer or flown on an airplane. Therefore, whether the engine produced its rated horsepower was undetermined. Review of the meteorological conditions that existed around the time of the accident and a carburetor icing chart indicated that conditions were conducive to the formation of carburetor icing at cruise power. The engine was not equipped with a carburetor heat system. Therefore, it is likely that carburetor ice accumulated, which resulted in a partial loss of power once airborne. ## Factual narrative On April 9, 2020, about 1130 Pacific daylight time, a Buckman Bucks Special airplane, N9065F, was substantially damaged when it was involved in an accident near Prescott, Washington. The flight instructor and pilot were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. According to the pilot, during takeoff from a planted field, shortly after becoming airborne, the tailwheel-equipped airplane did not climb, and the pilot initiated a left turn to avoid trees and powerlines at the end of the strip. The left wing tip impacted the ground during the turn and the airplane landed hard and nosed over, resulting in substantial damage to the wings and vertical stabilizer. The pilot reported a lack of performance that would not allow the airplane to gain altitude. A postaccident examination of the engine revealed several anomalies. A portion of a fuel line was found looped around an engine mount, partially collapsing the line due to the sharp bend. A soft fuel pump line was attached to the impulse side of the fuel pump. The induction air filter was removed, and the pleats displayed contamination, were gray in color, and were not coated in the protective filter oil. The carburetor venting tubing was modified and ran down the engine mount toward the bottom of the engine firewall. The beginning of the exhaust expansion chamber had a sharp 90° bend. The engine was test run was for several minutes at different power settings. The engine operated normally, and no anomalies were observed. It is unknown if the engine produced the specified 65 horsepower, as it was not test run on an engine dynamometer or test flown on an airplane. The engine did not have a carburetor heat system. Review of the engine maintenance logbook revealed that the engine was most recently inspected on August 5, 2019, about 17 hours of operation before the accident. On February 2, 2020, new carburetor sockets were installed. On March 21, 2020, about 3 hours of operation before the accident, floats and new jets were installed on the carburetors. Review of the meteorological conditions that existed around the time of the accident and the carburetor icing chart from FAA Special Airworthiness Information Bulletin CE-09-35 “Carburetor Icing Prevention” indicated a potential for serious icing at cruise power at the temperature and dew point that existed around the time of the accident. ## Aircraft - Registration: [N9065F](https://openairdocs.org/aircraft/N9065F), registered now, S/N BS-01, built 1997 (OpenAirDocs) - Reported make and model: Buckman Bucks Special - Registry model: [Buckman Donald F BUCKS SPECIAL](https://openairdocs.org/model/buckman-donald-f-bucks-special) (registry code 05630BV) (OpenAirDocs) - Registry engine: [Bombardier ROTAX (ALL)](https://openairdocs.org/engine/bombardier-rotax-all) (registry code 09050, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: BS-01 - Year built: 1997 - Airframe hours: 253.8 - Engines: Rotax 582 65 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Condition, August 5, 2019 - Departed: PVT, Prescott, WA - Destination: ALW, Walla Walla, WA - Airport: PVT, None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 71; injuries: none; flight instructor, commercial, airline transport; airplane ratings: multi-engine land, single-engine land, single-engine sea, multi-engine sea; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review February 16, 2019; seat: right; flight hours: 20,000 total, 15 in this make and model, 20,000 as pilot in command, 14 in the last 90 days, 8 in the last 30 days, 3 in the last 24 hours - Pilot; age 46; injuries: none; private; airplane ratings: single-engine land; medical: class 3, without waivers/limitations; last flight review December 4, 2019; seat: left; flight hours: 348 total, 3 in this make and model, 225 as pilot in command, 10 in the last 90 days, 3 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 3 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 55 °F - Observed at: PVT - METAR: METAR KALW 091753Z 26005KT 10SM CLR 14/01 A3012 RMK AO2 SLP200 T01390006 10139 20039 58007= ## 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 20200409002819A](https://openairdocs.org/incident/20200409002819A), Apr 9, 2020: Buckman Donald F BUCKS SPECIAL, Prescott, WA, Substantial damage. During takeoff and climb, pilot stated that the aircraft was not climbing or making enough power to clear power lines off the end of the runway. The pilot made… ## Docket (5 files) The files NTSB released with the investigation on June 14, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=101169. 18.7 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 10.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13259899&FileExtension=pdf&FileName=6120-signed_Redacted-Rel.pdf - Owners wreckage examination notes (item 2, PDF, 2 pages, 112 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13260263&FileExtension=pdf&FileName=RE_%20WPR20LA122%20Owners%20Examination%20Notes_Redacted-Rel.pdf - FAA carburetor icing prevention CE-09-35 (item 3, PDF, 3 pages, 107 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13920365&FileExtension=pdf&FileName=FAA%20Carburetor%20Icing%20Prevention%20CE-09-35-Rel.pdf - Engine logbook excerpt (item 4, PDF, 1 page, 964 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13920110&FileExtension=pdf&FileName=IMG_2036_Redacted-Rel.pdf - Rotax examination report (item 5, PDF, 34 pages, 83 photos, 7.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13921172&FileExtension=pdf&FileName=Rotax%20Investigation%20Report_Redacted-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.