# NTSB WPR18LA022: Cessna P210N, N6582P, Mount Vernon, WA, October 28, 2017 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: October 28, 2017, 12:50 local (19:50 UTC) - Place: Mount Vernon, WA - Coordinates: 48.468887, -122.419723 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=48.4689&lon=-122.4197&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: 3 uninjured - Status: Completed, report July 23, 2019 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 96272 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR18LA022 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/96272/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=96272 - Page: https://openairdocs.org/ntsb/WPR18LA022 ## Probable cause The failure of the right main landing gear (MLG) down-lock mechanism due to an out-of-tolerance down-lock hook, which resulted in the collapse of the right MLG during the landing roll. ## 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 P210N, 2 cases](https://openairdocs.org/ntsb-findings/01023210/cases.md?model=2073454), [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 P210N, 2 cases](https://openairdocs.org/ntsb-findings/01023210/cases.md?model=2073454), [All aircraft, 241 cases](https://openairdocs.org/ntsb-findings/01023210/cases.md) - [Maintenance](https://openairdocs.org/ntsb-findings/02062000): Personnel issues › Task performance · Other (probable cause); cases with it: [Cessna P210N, 2 cases](https://openairdocs.org/ntsb-findings/02062000/cases.md?model=2073454), [All aircraft, 143 cases](https://openairdocs.org/ntsb-findings/02062000/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); cases with it: [Cessna P210N, 8 cases](https://openairdocs.org/ntsb-events/330/sequence.md?model=2073454), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) - [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230); cases with it: [Cessna P210N, 7 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=2073454), [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 P210N, 12 cases](https://openairdocs.org/ntsb-events/300/sequence.md?model=2073454), [All aircraft, 3,643 cases](https://openairdocs.org/ntsb-events/300/sequence.md) - [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [Cessna P210N, 21 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=2073454), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis The commercial pilot configured the airplane for a straight-in approach when it was about 8 nautical miles from the destination airport. He verified that both main landing gear were down and locked by seeing that the landing gear indicator light had illuminated and by looking in a mirror mounted on the right wing and seeing that the gear were down. After a normal touchdown and during the landing roll, the airplane began to veer right, which the pilot believed was likely due to a flat tire. He then shut down the engine and steered the airplane to a grassy area adjacent to the runway. Postaccident examination of the airplane revealed that the right main landing gear (MLG) had collapsed and that the right aileron and right elevator had sustained substantial damage. Postaccident examination of the landing gear system revealed that the right MLG's down-lock hook exceeded the airplane manufacturer's maximum tolerance and that it was not over center, which is required for the landing gear to remain in the locked position. Based on the evidence, it is likely that the out-of-tolerance down-lock hook prevented the right MLG from locking after the pilot deployed the landing gear and resulted in the right MLG collapsing during the landing roll. The airplane service manual states that the proper rigging of the MLG down-lock mechanism should be verified every 200 hours. A review of the maintenance logbooks revealed no entries related to the rigging, which is not always documented in the maintenance logbook following each service. Therefore, it could not be determined whether a maintenance event led to the out-of tolerance right MLG down-hook or if it became out of tolerance over time. ## Factual narrative On October 28, 2017, about 1250 Pacific daylight time, a Cessna P210N airplane, N6582P, was substantially damaged following a collapse of its right main landing gear at Skagit Regional Airport (BVS), Burlington, Washington. The commercial pilot and two passengers were not injured. The airplane was registered to Insurance Solutions, Inc. and operated by the pilot under the provision of Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed and no flight plan was filed for the flight, which departed Snohomish County Airport (PAE), Everett, Washington at 1150. According to the pilot, after an uneventful flight, he began a descent for a straight in approach to land on runway 29 and deployed the landing gear about 8 nautical miles from the airport. He verified that the landing gear down indicator light had illuminated and then observed the landing gear in the down position through a mirror mounted to the radar on the right wing. The pilot subsequently checked the gear position again when the airplane was about 4 nm from the airport and then configured the airplane for a normal landing with 10° of wing flaps. Moments before the airplane touched down, the pilot deployed 30° of wing flaps. The airplane touched down normally and transitioned into a landing roll; however, the right main landing gear collapsed, which the pilot perceived as a loss of tire pressure to the right main landing gear wheel. He subsequently retarded the mixture control to the full lean position and shut off the engine while he steered the airplane until it came to rest in a grass area to the right of the runway. Photographs of the accident airplane furnished by the Federal Aviation Administration inspectors showed substantial damage to the right aileron and right elevator. The 6 seat, high-wing, retractable gear airplane was manufactured in 1978 and had been registered to the accident pilot since August 8, 2016. At the time of the accident, the airplane had accumulated a total of 3 flight hours since the airplane's most recent annual inspection, which was completed on October 9, 2017 at a recorded airframe total time of 4,342 flight hours. The logbook entry showed that the right main landing gear saddle screws were tightened, but did not indicate that a landing gear swing was accomplished. The pilot did not recall experiencing any landing gear problems before the accident flight nor had the previous owner, who owned the airplane from 1999 to 2016, disclose any landing gear anomalies to him at the time of purchase. The airplane's main landing gear system was hydraulically powered with electrical circuits to control and indicate landing gear position. During normal operation, gear selection is accomplished by moving a gear selector handle located in the switch panel. Once the landing gear position is selected, hydraulic fluid is supplied to the main landing gear actuators by an electrically-powered power pack assembly, whichthen drives the main landing gear into the desired position. A representative of the airframe manufacturer reported that the landing gear deployment system uses a down lock hook that locks the landing gear in the deployed position, but added that the hook needs to be over center to remain locked. The over center must be rigged periodically, which can be accomplished with a special down lock tool, as the hook can wear out over numerous cycles or when the system is not rigged properly. However, this cannot be completed if the down lock hook is out of tolerance. According to an excerpt from the airplane service manual, proper rigging of the downlock should be verified every 200 flight hours. The airframe and powerplant mechanic that recovered the airplane reported that he was unable to force the right main landing gear to free fall after the accident from its retracted position. A subsequent examination of the landing gear system was performed by the same mechanic with oversight from a representative of the Federal Aviation Administration. The examination team removed the fuselage floor panels and completed two full landing gear retractions and extensions, but were unable to replicate the landing gear failure. During both extensions, the landing gear downlock tube seated within the saddle as designed and the landing gear instrument panel indicator showed the landing gear in the down and locked position. The right main landing gear down lock hook appeared worn when compared to the left main landing gear hook. The right landing gear up lock rigging was tested at a later date and indicated that the down lock hook over center exceeded the prescribed maximum tolerance when compared to the left main landing gear using a tool specifically designed to verify the over center position of the down lock hook. ## Aircraft - Registration: [N6582P](https://openairdocs.org/aircraft/N6582P), registered now, S/N P21000191, built 1978 (OpenAirDocs) - Reported make and model: CESSNA P210N (N) - Registry model: [Cessna P210N](https://openairdocs.org/model/cessna-p210n) (registry code 2073454) (OpenAirDocs) - Registry engine: [Continental TSIO-520 series](https://openairdocs.org/engine/continental-tsio-520-series) (registry code 17040, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: P21000191 - Year built: 1978 - Airframe hours: 4342.25 - Engines: Continental TSIO-510-P5B 310 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, October 9, 2017, 3 hours before - Departed: PAE, EVERETT, WA - Destination: BVS, Mount Vernon, WA - Airport: BVS, Skagit Rgnl, runway 29, 5,478 × 100 ft, asphalt - Equipment: Stall warning system, Auto-pilot, Electronic flight bag or handheld device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 62; injuries: none; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review October 4, 2017; seat: left; restraint: 3-point; flight hours: 1,588 total, 35 in this make and model, 1,500 as pilot in command, 3 in the last 90 days, 3 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 61 °F, dew point 52 °F - Altimeter: 30.00 inHg - Observed at: BVS ## 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 20171028020439A](https://openairdocs.org/incident/20171028020439A), Oct 28, 2017: Cessna P210N, Mt Vernon, WA, Substantial damage. On approach to rnwy 29, PIC checked gear postion using indicator light and the mirrors mounted outside the aircraft and all landing gear appeared down and… ## Docket (7 files) The files NTSB released with the investigation on February 11, 2019, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=96272. 4.5 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 708 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40470314&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Record of Conversations (item 2, .PDF, 72 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40470315&FileExtension=.PDF&FileName=Record%20of%20Conversations-Master.PDF - Excerpts from Aircraft Logbooks (item 3, .PDF, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40470316&FileExtension=.PDF&FileName=Excerpts%20from%20Aircraft%20Logbooks-Master.PDF - Landing Gear Interval Inspection Requirement Excerpt from Service Manual (item 4, .PDF, 60 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40470317&FileExtension=.PDF&FileName=Landing%20Gear%20Interval%20Inspection%20Requirement%20Excerpt%20from%20Service%20Manual-Master.PDF - Landing Gear System Excerpt from Pilot's Operating Handbook (item 5, .PDF, 111 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40470318&FileExtension=.PDF&FileName=Landing%20Gear%20System%20Excerpt%20from%20Pilot%27s%20Operating%20Handbook-Master.PDF - Examination Report Furnished by Recovery Service (item 6, .PDF, 10 photos, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40470319&FileExtension=.PDF&FileName=Examination%20Report%20Furnished%20by%20Recovery%20Service-Master.PDF - Accident Photographs (item 7, .PDF, 11 photos, 686 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40470320&FileExtension=.PDF&FileName=Accident%20Photographs-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.