# NTSB SEA96LA162: Conkey/Wapelhorst Lancair 235, N235WC, Cottage Grove, OR, July 20, 1996 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 20, 1996, 16:30 local (23:30 UTC) - Place: Cottage Grove, OR - Coordinates: 43.710731, -123.029838 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.7107&lon=-123.0298&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report May 23, 1997 - Report: Approved by Office Director - NTSB case key (mKey): 42424 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA96LA162 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/42424/pdf - Page: https://openairdocs.org/ntsb/SEA96LA162 ## Probable cause release of the main landing gear locking mechanism for undetermined reason(s). ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Gear collapsed, takeoff - roll/run - landing gear,gear locking mechanism - unlocked (cause) - reason for occurrence undetermined (cause) - weather condition - crosswind - Loss of control - on ground/water, takeoff - roll/run - directional control - not possible - ground loop/swerve - On ground/water collision with object, other - object - aircraft parked/standing ## Analysis During the takeoff roll on runway 33, the left main landing gear collapsed as the aircraft was accelerating through about 55 to 60 knots. The pilot/co-owner of the aircraft reported that he was unable to identify any mechanical malfunction which have would allowed the left main gear to collapse. He also reported that the gear down lights were illuminated during the takeoff checklist. The reason for the release of the left main gear from the down and locked position could not be determined. However, a 5 to 10 knot quartering right crosswind existed at the time of the takeoff. Once the aircraft settled onto the left wing, the pilot was unable to maintain directional control, and the aircraft slid into another aircraft that was parked off the runway. ## Factual narrative On July 20, 1996, approximately 1600 Pacific daylight time, a Conkey/Wapelhorst homebuilt Lancair 235, N235WC, registered to and being flown by a private pilot, was substantially damaged when the left main landing gear collapsed during the takeoff roll at the Cottage Grove airport, Cottage Grove, Oregon. The pilot and passenger were uninjured. Visual meteorological conditions prevailed and no flight plan had been filed. The flight, which was to have been local, was to be operated under 14CFR91. The pilot reported that he commenced the takeoff roll on runway 33, with an estimated wind of 05-10 knots from 010 degrees. As the aircraft accelerated through 55-60 knots the aircraft's left wing suddenly dropped. The pilot aborted the takeoff and the aircraft slid approximately 200 feet before leaving the west side of the runway and eventually impacting a parked Stinson 30 feet west of the runway. The pilot reported that he "could not determine any failures that (would have) caused the left wheel to collapse inboard." The Lancair main landing gear fold inboard into wheel wells in the lower fuselage. They are normally held in the down and locked position by hydraulic pressure. The pilot reported observing that all three gear down lights were illuminated during the takeoff checklist. ## Aircraft - Registration: [N235WC](https://openairdocs.org/deregistered/N235WC-2011-11-09), registration cancelled 2011-11-09, S/N 001, built 1992 (OpenAirDocs) - Reported make and model: Conkey/Wapelhorst LANCAIR 235 (LANCAIR 23) - Registry model: [Conkey D R / Wapelhorst J A LANCAIR 235](https://openairdocs.org/model/conkey-d-r-wapelhorst-j-a-lancair-235) (registry code 056184V) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 001 - Airframe hours: 328 - Engines: Lycoming O-235-L2C 125 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Conkey, Denis, R. - Registered owner: Conkey & Wapelhorst - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, July 18, 1996, 6 hours before - Departed: 61S - Airport: 61S, Cottage Grove State, runway 33, 3,200 × 60 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 44; private; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 2,615 total, 222 in this make and model, 28 in the last 90 days, 8 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 10° at 10 knots - Visibility: 20 statute miles - Lowest ceiling: none - Temperature: 75 °F ## 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 19960720019159A](https://openairdocs.org/incident/19960720019159A), Jul 20, 1996: Amtr LANCAIR, Cottage Grove, OR, Substantial damage. Left main gear collapsed on takeoff roll. Aborted. Slid off runway. Cause collapsed unknown. ## Other investigations on N235WC (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 LAX03CA257](https://openairdocs.org/ntsb/LAX03CA257), Jul 26, 2003: Lancair 235 (N235WC), Page, AZ, substantial damage. Probable cause: The pilot's misjudged landing flare, which resulted in a hard landing and his improper recovery from a bounced landing. Inadvertent entry into a porpoise pilot-induced oscillation, and high density… 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.