# NTSB WPR16LA018: Cessna 120, N3124N, Lone Pine, CA, October 24, 2015 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: October 24, 2015, 15:00 local (22:00 UTC) - Place: Lone Pine, CA - Coordinates: 36.58889, -118.0475 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.5889&lon=-118.0475&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report August 1, 2016 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: FAA Reno FSDO - NTSB case key (mKey): 92240 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR16LA018 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/92240/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=92240 - Page: https://openairdocs.org/ntsb/WPR16LA018 ## Probable cause The fracture of the left main landing gear (MLG) wheel axle due to fatigue, which resulted in the separation of the left MLG wheel during takeoff from a dirt airstrip. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: main gear strut/axle/truck](https://openairdocs.org/ntsb-findings/01023213): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Cessna 120, 1 case](https://openairdocs.org/ntsb-findings/01023213/cases.md?model=2071402), [All aircraft, 86 cases](https://openairdocs.org/ntsb-findings/01023213/cases.md) - [Landing gear system: main gear strut/axle/truck](https://openairdocs.org/ntsb-findings/01023213): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause); cases with it: [Cessna 120, 1 case](https://openairdocs.org/ntsb-findings/01023213/cases.md?model=2071402), [All aircraft, 86 cases](https://openairdocs.org/ntsb-findings/01023213/cases.md) - [Runway/land/takeoff/taxi surface: soft surface](https://openairdocs.org/ntsb-findings/03023020): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Cessna 120, 2 cases](https://openairdocs.org/ntsb-findings/03023020/cases.md?model=2071402), [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. - [Takeoff: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) (defining event); cases with it: [Cessna 120, 1 case](https://openairdocs.org/ntsb-events/338/sequence.md?model=2071402), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) - [Takeoff: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Cessna 120, 20 cases](https://openairdocs.org/ntsb-events/096/sequence.md?model=2071402), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) ## Analysis The private pilot was taking off from a dirt airstrip for a personal cross-country flight. He reported that, during the takeoff roll, it felt like the left main landing gear had hit soft soil and that the drag had increased. He attempted to correct for the condition, but the left MLG wheel continued to drag. The airplane then suddenly nosed over, which resulted in substantial damage to the wings and empennage. Postaccident examination of the airplane revealed that the left MLG wheel axle was fractured, which resulted in the separation of the left MLG wheel. A detailed examination of the fracture surface identified a fatigue fracture that emanated from the outer surface of a circumferential weld between the lateral tube portion and the vertical plate portion of the axle. The investigation could not determine what event initiated the fatigue cracking; however, the origin areas were covered in zinc-chromate primer, which indicates that the axle was painted when the circumferential weld contained a preexisting crack. ## Factual narrative On October 24, 2015, about 1500 Pacific daylight time, a tailwheel-equipped Cessna 120 airplane, N3124N, sustained substantial damage following a nose over during takeoff at the Lone Pine Airport, Lone Pine, California. The private pilot was not injured. The flight was being operated as a personal cross country flight under the provisions of 14 Code of Federal Regulations Part 91 when the accident occurred. Visual meteorological conditions prevailed and no flight plan had been filed for the flight destined to Tehachapi, California. In a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge, the pilot stated that he was on his way back home from a weekend trip. During the takeoff roll on the dirt runway, just after raising the tail off the ground, he felt the sensation of hitting soft soil with the left main landing gear. He attempted to correct for the condition, but the left main landing gear wheel continued to drag, and then the airplane suddenly nosed over. During the nose over, the airplane sustained substantial damage to the wings and empennage. Postaccident examination of the airplane revealed that the left main landing gear wheel axle was fractured. A detailed examination of the fracture surface by the NTSB Materials Laboratory showed a fatigue fracture that emanated from the outer surface of a circumferential weld between the lateral tube portion and the vertical plate portion of the axle. The fatigue crack portions at the origin areas was covered with yellow deposits. The yellow deposits was identified by EDS spectra as zinc chromate, a compound found in primer paint. ## Aircraft - Registration: [N3124N](https://openairdocs.org/deregistered/N3124N-2016-03-05), registration cancelled 2016-03-05, S/N 13382, built 1947 (OpenAirDocs) - Reported make and model: CESSNA 120 (NO SERIES) - Registry model: [Cessna 120](https://openairdocs.org/model/cessna-120) (registry code 2071402) (OpenAirDocs) - Registry engine: [Continental C85 series](https://openairdocs.org/engine/continental-c85-series) (registry code 17008, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 13382 - Year built: 1947 - Airframe hours: 4162 - Engines: CONT MOTOR C85 SERIES 85 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, March 28, 2015, 20 hours before - Departed: O26, Lone Pine, CA - Destination: TSP, TEHACHAPI, CA - Airport: O26, Lone Pine, runway 13, 2,391 × 90 ft, dirt - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 24; injuries: none; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review February 10, 2014; seat: left; restraint: 3-point; flight hours: 420 total, 200 in this make and model, 380 as pilot in command, 90 in the last 90 days, 30 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 160° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 75 °F, dew point 25 °F - Altimeter: 30.04 inHg - Observed at: KBIH, 49 nm away ## Docket (2 files) The files NTSB released with the investigation on May 18, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=92240. 1.9 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 906 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40440231&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Materials Laboratory Factual Report (item 2, .PDF, 6 photos, 954 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40440230&FileExtension=.PDF&FileName=Materials%20Laboratory%20Factual%20Report-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.