# NTSB CHI05CA003: Sinclair Zenith 701, N701TD, Augusta, KS, October 8, 2004 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: October 8, 2004, 18:00 local (23:00 UTC) - Place: Augusta, KS - Coordinates: 37.666667, -97.016944 - Nearby events: https://openairdocs.org/map.md?lat=37.6667&lon=-97.0169&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report December 28, 2004 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 60390 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI05CA003 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/60390/pdf - Page: https://openairdocs.org/ntsb/CHI05CA003 ## Probable cause The manufacturer's inadequate design/production of the landing gear axle leading to its separation and the airplanes subsequent nose over during the landing roll.. A factor was the axle's separation from its spring. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, landing - roll - landing gear - inadequate, manufacturer (cause) - landing gear,axle - separation (contributing factor) - Nose over, landing - roll - terrain condition - ground ## Analysis The experimental amateur-built tailwheel airplane sustained substantial damage when the airplane nosed over during a landing. The pilot's accident report stated, "On touch down at private strip, landing slightly heavy but nothing excessive. Left main wheel contacted a slight depression and the axle separated. Left gear mainspring dug in causing plane to nose over [and] rotate to the left. Left over momentum caused the right wing to then strike the runway. After stopping, the tail then dropped back onto the ground." The pilot's safety recommendation stated that the "accident would not have happened if the axle assembly have been designed with adequate structure ... ." The axle manufacturer stated that ownership changed in November of 2000. The earlier company produced the WHLA7 Flange Mount Axles shipped with the accident airplane's kit. The current company designed the same model axle to have a "reinforcing ring welded to the base at the axle flange interface and the larger diameter hole in the flange base that accepts the axle stub." The manufacturer issued a Service Bulletin SRV101804 that showed the new design and an exchange program. That service bulletin is available through their website, www.matcomfg.com, on its technical support page. ## Factual narrative On October 8, 2004, about 1800 central daylight time, an experimental amateur-built tailwheel Sinclair Zenith CH 701 airplane, N701TD, sustained substantial damage when the airplane nosed over during a landing at a private airstrip near Augusta, Kansas. The personal flight was operating under 14 CFR Part 91. Visual meteorological conditions prevailed at the time of the accident. No flight plan was on file. The pilot reported no injuries. The flight originated from a private airstrip near Augusta, Kansas, at 1750. The pilot's accident report stated: On touch down at private strip, landing slightly heavy but nothing excessive. Left main wheel contacted a slight depression and the axle separated. Left gear mainspring dug in causing plane to nose over [and] rotate to the left. Left over momentum caused the right wing to then strike the runway. After stopping, the tail then dropped back onto the ground. The pilot stated that there was 68.5 hours of total time on the axle assembly and his safety recommendation stated that the "accident would not have happened if the axle assembly have been designed with adequate structure ... ." Matco Mfg, the axle manufacturer, was contacted. The manufacturer stated that ownership changed in November of 2000. The earlier company produced the WHLA7 Flange Mount Axles shipped with the accident airplane's kit. The current company designed the same model axle to have a "reinforcing ring welded to the base at the axle flange interface and the larger diameter hole in the flange base that accepts the axle stub." The manufacturer issued a Service Bulletin SRV101804 that showed the new design and an exchange program. That service bulletin is available through their website, www.matcomfg.com, on its technical support page and is appended to the docket material associated with this case. ## Aircraft - Registration: [N701TD](https://openairdocs.org/deregistered/N701TD-2011-04-07), registration cancelled 2011-04-07, S/N 7-3993, built 2004 (OpenAirDocs) - Reported make and model: Sinclair Zenith 701 - Registry model: [Sinclair Michael A ZENITH CH 701](https://openairdocs.org/model/sinclair-michael-a-zenith-ch-701) (registry code 056151O) (OpenAirDocs) - Registry engine: [Rotax SEE BOMBADIER](https://openairdocs.org/engine/rotax-see-bombadier) (registry code 55555, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 7-3993 - Engines: Rotax 912 UL 80 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Michael A. Sinclair - Airworthiness certificate: Special, Experimental (Special) - Departed: PVT, Augusta, KS - Destination: PVT, Augusta, KS - Airport: PVT, runway 36, 700 × 70 ft, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 55; injuries: none; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; last flight review October 20, 2003; seat: left; flight hours: 148 total, 67 in this make and model, 148 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Wind: 10° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 54 °F - Altimeter: 30.04 inHg - Observed at: AAO, 15 nm away ## 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 20041008026799A](https://openairdocs.org/incident/20041008026799A), Oct 8, 2004: Amtr ZENITHCH701, Augusta, KS, Substantial damage. (-23) While landing at Private grass strip 6 miles south of Augusta, KS, left tire hit chuck hole and left wheel separated from aircraft. Subsequently, the… 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.