# NTSB LAX03LA085: Mooney M20D, N6639U, Casa Grande, AZ, January 24, 2003 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: January 24, 2003, 11:45 local (18:45 UTC) - Place: Casa Grande, AZ - Coordinates: 32.87067, -111.729873 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=32.8707&lon=-111.7299&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report October 28, 2004 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 56475 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX03LA085 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/56475/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=56475 - Page: https://openairdocs.org/ntsb/LAX03LA085 ## Probable cause Collapse of the landing gear during landing rollout, resulting from the pilot/mechanic's incorrect landing gear locking mechanism (linkage) adjustment. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Gear collapsed, landing - roll - maintenance,adjustment - incorrect, owner/pilot mechanic (cause) - landing gear,gear locking mechanism - unlocked - On ground/water collision with object, landing - roll - object - runway light ## Analysis Following a normal touchdown and during the rollout, the airplane's main landing gear collapsed. Thereafter, as the airplane slid to a stop it veered off the runway and collided with a runway light. The pilot reported that during his approach for landing, he had verified that the landing gear was extended. He had confirmed its extension by observing the green gear down lights illuminate. The pilot had previously performed maintenance to the landing gear system. The airplane had been operated for 4.77 hours since receiving its last annual inspection. According to the pilot, the gear collapsed due to an adjustment problem, which prevented the over-center linkage from completely locking. The FAA indicated that the pilot, who holds an airframe and powerplant mechanic certificate, had performed the landing gear related maintenance. ## Factual narrative On January 24, 2003, about 1145 mountain standard time, a Mooney M20D, N6639U, experienced the collapse of its main landing gear during landing rollout on runway 05 at the Casa Grande Municipal Airport, Casa Grande, Arizona. The airplane was substantially damaged. Neither the private pilot, who operated the airplane, nor the passenger was injured. The airplane was being operated on a personal flight under the provisions of 14 CFR Part 91. Visual meteorological conditions prevailed. No flight plan had been filed for the local area flight that originated from Casa Grande about 1045. The pilot reported that during his approach for landing, he had checked three times to confirm that the landing gear was extended and the green landing gear down lights were illuminated. Everything appeared satisfactory, and he made a normal landing. As the airplane decelerated on the runway, the main landing gear collapsed. Thereafter, as the airplane veered off the runway it collided with a runway light. On February 7, 2003, the Federal Aviation Administration (FAA) coordinator reported that the airplane examination revealed substantial damage had resulted during the gear collapse/impact event. The pilot reported that he owns the accident airplane. The airplane had been operated for 4.77 hours since receiving its last annual inspection. The pilot holds an FAA airframe and powerplant mechanic certificate, and he indicated that the airplane had previously undergone maintenance to its landing gear. According to the pilot, during the mishap the landing gear collapsed due to an adjustment problem, which prevented the over-center linkage from completely locking. The FAA indicated that the pilot/mechanic had performed the landing gear related maintenance. ## Aircraft - Registration: [N6639U](https://openairdocs.org/deregistered/N6639U-2014-11-12), registration cancelled 2014-11-12, S/N 134, built 1963 (OpenAirDocs) - Reported make and model: Mooney M20D - Registry model: [Mooney M20D](https://openairdocs.org/model/mooney-m20d) (registry code 5870210) (OpenAirDocs) - Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 134 - Airframe hours: 2834 - Engines: Lycoming O-360-A1D 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Jack H. Arend - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 12, 2002, 5 hours before - Departed: CGZ, Casa Grande, AZ - Destination: CGZ, Casa Grande, AZ - Airport: CGZ, Casa Grande Municipal, runway 05, 5,200 × 100 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 64; injuries: none; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 1,261 total, 235 in this make and model, 1,092 as pilot in command, 13 in the last 90 days, 5 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 140° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 66 °F, dew point 36 °F - Altimeter: 30.04 inHg - Observed at: CGZ ## 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 20030124001199A](https://openairdocs.org/incident/20030124001199A), Jan 24, 2003: Mooney M20D, Casa Grande, AZ, Substantial damage. (.19) On January 24, 2003, about 1140 mountain standard time, a Mooney M20D, N6639U, experienced the collapse of its main landing gear during landing rollout… ## Docket (1 files) The files NTSB released with the investigation on August 25, 2004, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=56475. 299 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 299 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40380821&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-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.