# NTSB ANC13LA016: Cessna 150C, N1901Z, Juneau, AK, December 13, 2012 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: December 13, 2012, 14:09 local (18:09 UTC) - Place: Juneau, AK - Coordinates: 58.354721, -134.57611 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=58.3547&lon=-134.5761&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report April 3, 2013 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: Federal Aviation Administration - NTSB case key (mKey): 85803 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC13LA016 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/85803/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=85803 - Page: https://openairdocs.org/ntsb/ANC13LA016 ## Probable cause The collapse of the left main landing gear during the landing roll, as a result of fatigue cracking. Contributing to the accident was the improper maintenance of the landing gear. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: main landing gear](https://openairdocs.org/ntsb-findings/01023210): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Cessna 150C, 1 case](https://openairdocs.org/ntsb-findings/01023210/cases.md?model=2071808), [All aircraft, 241 cases](https://openairdocs.org/ntsb-findings/01023210/cases.md) - [Landing gear system: main landing gear](https://openairdocs.org/ntsb-findings/01023210): Aircraft › Aircraft systems · Incorrect service/maintenance (probable cause); cases with it: [Cessna 150C, 1 case](https://openairdocs.org/ntsb-findings/01023210/cases.md?model=2071808), [All aircraft, 241 cases](https://openairdocs.org/ntsb-findings/01023210/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: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [Cessna 150C, 2 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=2071808), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis The flight instructor was demonstrating a short field, three-point landing. The touchdown was normal, but during the landing roll a gust of wind pushed the airplane, and it began to turn to the right. The instructor applied left brake in an attempt to correct for the right turn, and the airplane’s left main landing gear broke. As the broken gear leg dug into the runway, the airplane pivoted 180 degrees to the left, and the left wing struck the runway. The airplane sustained substantial damage to the left wing and fuselage. The flight instructor stated that during the last annual inspection, about 4 months before the accident, he observed corrosion on the main landing gear legs and ground it off using a hand-held grinder. The service manual specified to carefully remove any rust by light sanding; the sanding must blend the damage into the adjacent area in an approximate 20:1 ratio. Examination of the landing gear revealed evidence of the improper maintenance and corrosion damage, which weakened the gear and led to fatigue cracking and an overstress fracture. ## Factual narrative On December 13, 2012, about 1409 Alaska standard time, a tailwheel-equipped Cessna 150C airplane, N1901Z, sustained substantial damage while landing at the Juneau International Airport, Juneau, Alaska. The airplane was being operated as a visual flight rules (VFR) instructional flight under the provisions of Title 14, CFR Part 91, when the accident occurred. The student pilot, and the airline transport rated flight instructor (CFI) were not injured. Visual meteorological conditions prevailed, and no flight plan had been filed. During a telephone conversation with the National Transportation Safety Board investigator-in-charge on December 14, the CFI stated that the accident flight originated at the Juneau International Airport, for a local flight to practice stop-and-go landings. At the time of the accident he was demonstrating a short field, three-point landing. He said that the touchdown was normal, but during the landing roll a gust of wind pushed the airplane, and it began to turn to the right. He applied left brake in an attempt to correct for the right turn, and the airplane’s left main landing gear broke. As the broken gear leg dug into the runway, the airplane pivoted 180 degree to the left, and the left wing struck the runway. The airplane sustained substantial damage to the left wing and fuselage. The CFI, who is also a certificated airframe and powerplant (A & P) mechanic, stated that during the annual inspection in August, he observed corrosion on the main landing gear legs. The corrosion was ground off with a hand held grinder, and Zinc Chromate Primer applied. The Cessna 100 Series Service Manual, Section 5-5A Corrosion Control on Landing Gear Springs specifies in part: Carefully remove any rust by light sanding; the sanding must blend the damage into the adjacent area in an approximate 20:1 ratio. The fracture face contained a crescent-shaped fracture on the upper forward surface which is consistent with features of fatigue cracking. The remaining fracture surface contained a coarse grainy appearance, clear chevron markings, and a shear lip, which are consistent of an overstress fracture. Corrosion damage and grinder marks were also present on the surfaces of the left landing gear leg. The closest weather reporting facility is Juneau International Airport. At 1353, an aviation routine weather report (METAR) at Juneau, Alaska, reported in part: wind, calm; visibility, 10 statute miles; light rain; few clouds at 2,000 feet; broken clouds at 3,900 feet; broken clouds at 5,000 feet; temperature, 36 degrees F; dew point 32 degrees F; altimeter, 29.44 inHG. ## Aircraft - Registration: [N1901Z](https://openairdocs.org/deregistered/N1901Z-2013-11-01), registration cancelled 2013-11-01, S/N 15059701, built 1962 (OpenAirDocs) - Reported make and model: CESSNA 150C - Registry model: [Cessna 150C](https://openairdocs.org/model/cessna-150c) (registry code 2071808) (OpenAirDocs) - Registry engine: [Continental 0-200 series](https://openairdocs.org/engine/continental-0-200-series) (registry code 17020, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 15059701 - Airframe hours: 6911 - Engines: CONT MOTOR O-200 SERIES 100 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Alaska Flight Center Inc - Registered owner: Alaska Flight Center Inc - Airworthiness certificate: Standard, Utility - Last inspection: Annual, August 17, 2012 - Departed: JNU, Juneau, AK - Destination: Juneau, AK - Airport: PAJN, Juneau International Airport, runway 08, 8,457 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 66; injuries: none; commercial, flight instructor, airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review September 27, 2012; seat: right; flight hours: 6,000 total, 561 in this make and model, 6,000 as pilot in command, 26 in the last 90 days, 3 in the last 30 days, 1 in the last 24 hours - Student pilot; age 33; injuries: none; student; medical: class 3, with waivers/limitations; seat: left; flight hours: 166 total, 48 in this make and model, 22 as pilot in command, 15 in the last 90 days, 4 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: 3,900 ft broken - Temperature: 36 °F, dew point 32 °F - Altimeter: 29.44 inHg - Observed at: JNU ## 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 20121213028499A](https://openairdocs.org/incident/20121213028499A), Dec 13, 2012: Cessna 150C, Juneau, AK, Substantial damage. On December 13, 2012, the pilot of N1901Z was demonstrating a short field landing in a conventional gear Cessna 150 when the left gear leg fractured shortly… ## Other investigations on N1901Z (1) 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. - [NTSB DEN68D0182](https://openairdocs.org/ntsb/DEN68D0182), Dec 16, 1967: Cessna 150 (N1901Z), Longmont, CO, substantial damage ## Docket (3 files) The files NTSB released with the investigation on January 16, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=85803. 5.5 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40384413&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Record of Conversation (item 2, .PDF, 25 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40385149&FileExtension=.PDF&FileName=Record%20of%20Conversation-Master.PDF - Pilot Statement (item 3, .PDF, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40384418&FileExtension=.PDF&FileName=Pilot%20Statement-Redacted.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.