# NTSB WPR20LA193: Thatcher CX4, N274DR, Upland, CA, June 24, 2020 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Class 3 · Limited · Final report - Date: June 24, 2020, 11:45 local (18:45 UTC) - Place: Upland, CA - Coordinates: 34.109443, -117.694999 - Nearby events: https://openairdocs.org/map.md?lat=34.1094&lon=-117.6950&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-descent: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 101488 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR20LA193 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101488/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=101488 - Page: https://openairdocs.org/ntsb/WPR20LA193 ## Probable cause The inflight separation of the propeller assembly due to a fatigue fracture of the crankshaft. Contributing to the accident was the pilot’s restricted visibility during landing, which resulted in an excessive approach speed, a long landing, and subsequent impact with terrain. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip engine power section](https://openairdocs.org/ntsb-findings/01058520): Aircraft › Aircraft power plant · Fatigue/wear/corrosion (probable cause); cases with it: [David Reser CX4, 1 case](https://openairdocs.org/ntsb-findings/01058520/cases.md?model=05635I0), [All aircraft, 233 cases](https://openairdocs.org/ntsb-findings/01058520/cases.md) - [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained; cases with it: [David Reser CX4, 1 case](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=05635I0), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md) - [Attention/monitoring: monitoring equip/instruments](https://openairdocs.org/ntsb-findings/02021525): Personnel issues › Psychological · Pilot; cases with it: [David Reser CX4, 1 case](https://openairdocs.org/ntsb-findings/02021525/cases.md?model=05635I0), [All aircraft, 142 cases](https://openairdocs.org/ntsb-findings/02021525/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-descent: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [David Reser CX4, 1 case](https://openairdocs.org/ntsb-events/340/sequence.md?model=05635I0), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md) ## Analysis The pilot reported that while returning to the airport after an uneventful flight, the propeller separated from the engine, which resulted in the windscreen and canopy being covered with oil and restricting forward visibility. The pilot continued toward the airport; however, as the airplane crossed the threshold of the runway, he noted that he was going way too fast as he was attempting to keep the airplane aligned with the runway. Subsequently, the airplane touched down near the departure end of the runway, bounced, and impacted the ground. Postaccident examination of the airplane revealed substantial damage to the fuselage and both wings. The propeller assembly and a portion of the engine crankshaft was separated and not located. Examination of the remaining portion of the crankshaft revealed that two fractures initiated at the termination of a square keyway slot in the crankshaft. The presence of ratchet marks at the fracture origins and the presence of progressions marks along the fracture path were indicative of fatigue fracture initiation and growth. ## Factual narrative On June 24, 2020, about 1145 Pacific daylight time, a Thatcher CX4, N274DR, was substantially damaged when it was involved in an accident at Cable Airport (CCB), Upland, California. The pilot was seriously injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he was returning to CCB following an uneventful local flight when the propeller separated from the engine. He was about 1 mile from the airport at an altitude of about 1,100 ft above ground level (agl) at the time. The pilot said that oil covered the windscreen and canopy, restricting forward visibility; however, he continued to fly toward the airport. When the airplane crossed the threshold of the runway, it was about 50 ft agl, and “going way too fast,” as he was trying to look out to the side to keep the airplane aligned with the runway. The airplane touched down near the end of the runway and bounced. The airplane continued over a fence and collided with a dirt berm. Postaccident examination of the airplane by the pilot revealed that both wings and fuselage were substantially damaged. The propeller assembly and a portion of the engine crankshaft were separated and not located. The remaining portion of the crankshaft from the Hummel VW 2400CC engine was sent to the National Transportation Safety Board Materials Laboratory for further examination. Examination of the crankshaft revealed that two fractures initiated at the termination of a square keyway slot in the crankshaft. The presence of ratchet marks at the fracture origins and the presence of progressions marks along the fracture path were indicative of fatigue fracture initiation and growth. ## Aircraft - Registration: [N274DR](https://openairdocs.org/deregistered/N274DR-2022-12-31), registration cancelled 2022-12-31, S/N 122, built 2017 (OpenAirDocs) - Reported make and model: Thatcher CX4 (No Series) - Registry model: [David Reser CX4](https://openairdocs.org/model/david-reser-cx4) (registry code 05635I0) (OpenAirDocs) - Registry engine: [Volkswagen 2400](https://openairdocs.org/engine/volkswagen-2400) (registry code 63504, 4 cycle) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 122 - Year built: 2017 - Engines: Hummel VW 2400CC reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, July 2, 2021 - Departed: CCB, Upland, CA - Airport: CCB, Cable, runway 24, 3,863 × 75 ft, asphalt - Equipment: Electronic primary flight display ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 80; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review September 21, 2019; seat: center; flight hours: 1,130 total, 32 in this make and model, 1,130 as pilot in command, 12.7 in the last 90 days, 11.2 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 220° at 5 knots - Visibility: 8 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 59 °F - Altimeter: 29.86 inHg - Observed at: KCCB ## 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 20200624008679A](https://openairdocs.org/incident/20200624008679A), Jun 24, 2020: David Reser CX4, Upland, CA, Substantial damage. A home built cxr attempted a high speed landing at cable airport after reporting the propeller had separated in flight. He struck the ground and nosed into a… ## Docket (4 files) The files NTSB released with the investigation on June 22, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=101488. 8.5 MB in all. - NTSB materials laboratory report (item 1, PDF, 6 pages, 11 photos, 2.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12428946&FileExtension=pdf&FileName=Materials%20Laboratory%20Factual%20Report%2021-007-Rel.pdf - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 2, PDF, 7 pages, 5.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12428646&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - Evidence control form (item 3, PDF, 1 page, 140 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12428956&FileExtension=pdf&FileName=Evidence%20Control%20Form-Rel.pdf - Photo array (item 4, PDF, 2 pages, 2 photos, 359 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12428422&FileExtension=pdf&FileName=Photo%20Array-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.