# NTSB WPR16LA015: Cessna 310J, N3123L, Tucson, AZ, October 10, 2015 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: October 10, 2015, 11:00 local (18:00 UTC) - Place: Tucson, AZ - Coordinates: 32.109443, -110.937774 - Nearby events: https://openairdocs.org/map.md?lat=32.1094&lon=-110.9378&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-flare/touchdown: Landing gear collapse](https://openairdocs.org/ntsb-events/094) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report July 11, 2016 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: FEDERAL AVIATION ADMINISTRATION, Textron Aviation - NTSB case key (mKey): 92208 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR16LA015 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/92208/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=92208 - Page: https://openairdocs.org/ntsb/WPR16LA015 ## Probable cause The insufficient right main landing gear (MLG) down-lock tension due to maintenance personnel's failure to perform a rigging procedure during the airplane's most recent inspection, which resulted in the right MLG collapsing during landing. ## 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 310J, 2 cases](https://openairdocs.org/ntsb-findings/01023210/cases.md?model=2074226), [All aircraft, 241 cases](https://openairdocs.org/ntsb-findings/01023210/cases.md) - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Cessna 310J, 1 case](https://openairdocs.org/ntsb-findings/02062010/cases.md?model=2074226), [All aircraft, 320 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md) - [Action: forgotten action/omission](https://openairdocs.org/ntsb-findings/02041035): Personnel issues › Action/decision · Maintenance personnel (probable cause); cases with it: [Cessna 310J, 1 case](https://openairdocs.org/ntsb-findings/02041035/cases.md?model=2074226), [All aircraft, 440 cases](https://openairdocs.org/ntsb-findings/02041035/cases.md) - [Maintenance/inspections: scheduled maint checks](https://openairdocs.org/ntsb-findings/01010520): Aircraft › Aircraft handling/service · Incorrect service/maintenance (probable cause); cases with it: [Cessna 310J, 1 case](https://openairdocs.org/ntsb-findings/01010520/cases.md?model=2074226), [All aircraft, 76 cases](https://openairdocs.org/ntsb-findings/01010520/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 310J, 2 cases](https://openairdocs.org/ntsb-findings/01023210/cases.md?model=2074226), [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-flare/touchdown: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [Cessna 310J, 3 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=2074226), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) - [Landing-landing roll: Runway excursion](https://openairdocs.org/ntsb-events/300); cases with it: [Cessna 310J, 1 case](https://openairdocs.org/ntsb-events/300/sequence.md?model=2074226), [All aircraft, 3,643 cases](https://openairdocs.org/ntsb-events/300/sequence.md) - [Landing-landing roll: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Cessna 310J, 3 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=2074226), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The commercial pilot and his passenger were returning to the airport after a 30-minute personal flight. The pilot reported that he configured the airplane for landing but that the landing gear down indication did not illuminate. The pilot cycled the landing gear several times, but the landing gear down indication still did not illuminate. After an air traffic controller confirmed that the landing gear was down, the pilot chose to initiate the landing. The airplane touched down uneventfully, but, about 3 seconds later, the right main landing gear (MLG) collapsed. The airplane subsequently veered right and departed the right side of the runway, which resulted in substantial damage to the right aileron and elevator. A postaccident examination of the landing gear system revealed that the right MLG down-lock tension was about 30 lbs less than the tension prescribed by the airplane's service manual. The fork bolt normally used to adjust the down-lock tension was covered in dirt and oil. Examination also revealed that the MLG nonadjustable drive tube had separated outboard a few inches from a clevis fitting. The signatures on the tube indicated that it failed in compression on the forward/aft plane. A review of maintenance records revealed that the airplane's last annual inspection occurred about 4 months before the accident. The condition of the fork bolt indicates that it had not been adjusted during this inspection. Further, the pilot reported that the rigging procedure in the service manual, which included an item to verify the landing gear down-lock brace tension, was not used during any recent inspections. Maintenance personnel's failure to perform the rigging procedure during the airplane's most recent annual inspection likely led to the insufficient down-lock tension and the drive tube's failure and the subsequent collapse of the right MLG due to the compression forces experienced upon touchdown. ## Factual narrative On October 10, 2015, about 1100 mountain standard time, a Cessna 310J airplane, N3123L, was substantially damaged during a landing attempt at Tucson International Airport (TUS), Tucson, Arizona. The airplane was operated as a personal flight under the provisions of Title 14 Code of Federal Regulations Part 91. The commercial pilot and his passenger were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight that departed TUS at 1030. According to the pilot, after a 30 minute flight with a friend they returned to TUS, but received an improper landing gear indication when the pilot attempted to deploy the landing gear. He flew south of the airport to troubleshoot the indication and then returned to the airport. The pilot elected to make a landing attempt after an air traffic controller confirmed the landing gear was extended. During touchdown, the right main landing gear collapsed, and the airplane departed the right side of the runway. A review of accident photographs by a National Transportation Safety Board (NTSB) investigator revealed substantial damage to the right elevator and right aileron. A flight instructor who was functioning as a passenger observed no abnormalities with the airplane until the landing gear down light failed to illuminate after the pilot attempted to deploy the landing gear. The passenger stated that the pilot used emergency checklists to troubleshoot the landing gear anomaly, but after several attempts to cycle the landing gear, the green light would not illuminate. They returned to the airport to attempt a landing. The touchdown was "normal and unremarkable", but approximately 3 seconds later the right main landing gear slowly collapsed, and the right wing contacted the ground. According to Federal Aviation Administration (FAA) records, the airplane was manufactured in 1965, and registered to Leading Edge Aviation on April 13, 1992. The airplane's most recent airworthiness certificate was issued on November 22, 1985. The airplane was powered by two Continental Motors, Inc. IO-520-E, normally-aspirated, direct drive, air cooled, 300 hp engines. A review of the airplane's maintenance records revealed the most recent annual inspection was completed on June 23, 2015, at 4,068 hours of total time in service. The airplane's most recent logbook entry indicated that a landing gear swing and extension were completed during the airplane's last annual inspection. The 1053 mountain standard time recorded weather observation at TUS, located at the accident site, included winds from 110 degrees at 14 knots, visibility 10 statute miles, clear, temperature 29 degrees C, dew point 12 degrees C, and an altimeter setting of 30.17 inches of mercury. The airplane is equipped with a fully retractable tricycle landing gear system comprised of two main landing gear wheels beneath each wing and a nose landing gear in the forward fuselage. Each landing gear is mechanically connected to a gearbox located aft of the pilot's seat, driven by a motor, and actuated by a landing gear switch on the instrument panel. An examination of the landing gear system was performed by a representative of the airframe manufacturer and an airframe and powerplant mechanic with oversight from the NTSB and the FAA. Initial inspection of the mechanical linkage within the landing gear wells showed no obvious signs of separation or failure; however, both main gear side brace lock links were disengaged by hand with little force when pulled together. The main landing gear intermediate drive tubes were disconnected, and a free fall test was performed to verify each gear could extend to the down and locked position. The main landing gear were retracted by hand about 30 degrees and dropped separately. Each gear returned to its down and locked position, and the locks were then disengaged by hand with little application of force. The floor panels and seats were removed to facilitate an examination of the motor assembly and drive tubes, which revealed the non-adjustable tube separated outboard a few inches from a lever attached to a clevis fitting. The drive tube signatures indicated that it failed in compression on the forward/aft plane. A contact signature was observed on the base of a clevis that connected the tube to a lever. According to the airframe logbook, the non-adjustable drive tube (p/n 0841138-1) was recently installed during an annual inspection that took place on June 23, 2015. The entry described the part as a "main gear retraction tube," and included the corresponding part number. Both landing gear actuator limit switches on the gear motor were tested to verify the landing gear "up" and "down" indications operated normally. The limit switches were tested separately with the battery on, and no anomalies were observed when the landing gear "up" indication was tested, but the landing gear "down" indication failed to illuminate. An electrical continuity test of the landing gear down actuator limit switch revealed the switch functioned intermittently. The down indicator switches on the main landing gear and wiring were not tested. According to the airplane's logbook, the landing gear actuator down limit switch was replaced on September 26, 2015. A hanging scale was used to measure the down lock tension for the main landing gear. The hook end of the hanging scale was attached to the lock link and pulled at a right angle. The left main landing gear down lock tension was about 17 lbs and the right main landing gear tension was about 11 lbs. According to the manufacturer, the prescribed tension is 40 to 60 lbs. for proper engagement and tension. The fork bolt is normally used to adjust down lock tension; however, the bolt was covered in grime indicating that it had not been adjusted during recent inspections. According to the pilot, he encountered a right main landing gear failure during a previous flight in 2013. He suspected the landing gear failure wascaused by a passenger seated in the rear right seat who damaged the floor panels with his foot during a flight before the first landing gear incident. Several mechanics visually inspected the airplane following the first incident, and discovered damage to the floor panels and landing gear drive tubes located under the front right seat in the cockpit. The tubes and right main landing gear switch were subsequently replaced by a mechanic who was assisted by the pilot. The mechanic responsible for endorsing the airplane's last annual inspection reported that he started working on the accident airplane in 2014. He was asked to inspect the airplane following the installation of several components that were replaced as a result of the pilot's previous landing gear anomalies. According to the mechanic, he placed the airplane on jacks and performed multiple landing gear swings, but did not observe any abnormalities. The pilot stated that the manufacturer's service manual was used to inspect the airplane; however, the airplane rigging procedure, which included a procedural item to verify the landing gear down lock brace tension, was not used during any of the inspections that followed the first landing gear failure. ## Aircraft - Registration: [N3123L](https://openairdocs.org/deregistered/N3123L-2018-05-30), registration cancelled 2018-05-30, S/N 310J0123, built 1965 (OpenAirDocs) - Reported make and model: CESSNA 310J - Registry model: [Cessna 310J](https://openairdocs.org/model/cessna-310j) (registry code 2074226) (OpenAirDocs) - Registry engine: [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series) (registry code 17032, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 310J0123 - Year built: 1965 - Airframe hours: 4068.2 - Engines: Continental Motors IO 520 E 300 horsepower reciprocating; Continental Motors IO 520 E 300 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Leading Edge Aviation Inc - Registered owner: Leading Edge Aviation Inc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 23, 2015, 1 hours before - Departed: TUS, TUCSON, AZ - Destination: TUS, TUCSON, AZ - Airport: TUS, Tucson Intl, runway 11R, 8,408 × 75 ft, asphalt - Equipment: Auto-pilot ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 65; injuries: none; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review October 7, 2015; seat: left; restraint: 4-point; flight hours: 3,350 total, 1,650 in this make and model, 3,285 as pilot in command, 10 in the last 90 days, 2.2 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 110° at 14 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 84 °F, dew point 54 °F - Altimeter: 30.17 inHg - Observed at: TUS ## Docket (8 files) The files NTSB released with the investigation on April 18, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=92208. 4.8 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40438963&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Record of Conversations (item 2, .PDF, 94 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40438964&FileExtension=.PDF&FileName=Record%20of%20Conversations-Master.PDF - Weather Reports and Records (item 3, .PDF, 67 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40438965&FileExtension=.PDF&FileName=Weather%20Reports%20and%20Records-Master.PDF - Excerpt from Aircraft Service Manual (item 4, .PDF, 67 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40438966&FileExtension=.PDF&FileName=Excerpt%20from%20Aircraft%20Service%20Manual-Master.PDF - Excerpts from Airframe Logbook (item 5, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40438967&FileExtension=.PDF&FileName=Excerpts%20from%20Airframe%20Logbook-Master.PDF - NTSB Landing Gear Examination Factual Report (item 6, .PDF, 6 photos, 591 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40438968&FileExtension=.PDF&FileName=NTSB%20Landing%20Gear%20Examination%20Factual%20Report-Master.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 7, .PDF, 54 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40438969&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Master.PDF - Accident Photos (item 8, .PDF, 6 photos, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40438970&FileExtension=.PDF&FileName=Accident%20Photos-Master.PDF From the NTSB's public API. 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