# NTSB ANC96LA062: Cessna 170B, N2760D, Togiak, AK, April 30, 1996 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: April 30, 1996, 12:50 local (20:50 UTC) - Place: Togiak, AK - Coordinates: 59.21009, -160.540374 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=59.2101&lon=-160.5404&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed, report February 1, 1997 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 2833 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC96LA062 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/2833/pdf - Page: https://openairdocs.org/ntsb/ANC96LA062 ## Probable cause fatigue failure of the right main landing gear strut. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Gear collapsed, landing - roll - landing gear,main gear strut - fatigue (cause) - Nose over, landing - roll ## Analysis The certificated private pilot was landing on a gravel area of beach next to a river. During the landing roll, the right main wheel assembly broke. The landing gear strut began dragging on the ground and the airplane nosed over. Examination of the gear strut revealed that it was broken along a horizontal plane, perpendicular to the outside vertical surface of the strut. A fracture had progressed through the upper mounting bolt holes that attach the axle and brake mounting plate to the strut. The surface of the fracture exhibited a dark brown/red appearance and ridges or stop marks radiating from the lower inside edge of the aft mounting bolt hole. These stop marks were similar in appearance to progressive beach marks, indicative of fatigue. The remaining fracture surface, at the inboard edge of the strut and between the bolt holes, exhibited a dull gray appearance and a shear lip oriented on about a 45 degree plane from the lower surface. The remaining fracture surface areas on both sides (forward and aft) of the bolt holes were also gray in appearance with small areas of red rust and corrosion. ## Factual narrative On April 30, 1996, about 1250 Alaska daylight time, a wheel equipped Cessna 170B, N2760D, crashed during landing in a remote area, about 4 miles southwest of Togiak, Alaska. The airplane was being operated as a visual flight rules (VFR) business flight under Title 14 CFR Part 91 when the accident occurred. The airplane, registered to and operated by the pilot, sustained substantial damage. The certificated private pilot and the sole passenger received minor injuries. Visual meteorological conditions prevailed. The flight originated at the Dillingham airport, Dillingham, Alaska, about 1135. A Federal Aviation Administration (FAA) airworthiness inspector, Anchorage Flight Standards District Office (FSDO), reported that the airplane was being utilized in support of the fishing vessel "Ultimate", also owned by the pilot. The pilot was landing on a gravel area of beach next to the Quigmy River. During the landing roll, the right main wheel assembly broke. The landing gear strut began dragging on the ground and the airplane nosed over. The lower end of the right main gear and axle assembly was examined by the National Transportation Safety Board (NTSB) investigator-in-charge (IIC). The lower end of the gear strut was broken along a horizontal plane, perpendicular to the outside vertical surface of the strut. It progressed through the upper mounting bolt holes that attach the axle and brake mounting plate to the strut. Examination of the lower fracture surface with a 10X and 25X magnifier revealed a dark brown/red surface about 13/16 wide and 9/16 high located between the upper mounting bolt holes. The surface also exhibited areas of rust and corrosion. The surface of the fracture exhibited ridges or stop marks radiating from the lower inside edge of the aft mounting bolt hole. These stop marks were similar in appearance to progressive beach marks. The remaining fracture surface, about 2/16 wide at the inboard edge of the strut and between the bolt holes, exhibited a dull gray appearance and a shear lip oriented on about a 45 degree plane from the lower surface. The remaining fracture surface areas on both sides (forward and aft) of the bolt holes were also gray in appearance with small areas of red rust and corrosion. ## Aircraft - Registration: [N2760D](https://openairdocs.org/deregistered/N2760D-2016-03-16), registration cancelled 2016-03-16, S/N 25302, built 1952 (OpenAirDocs) - Reported make and model: Cessna 170B - Registry model: [Cessna 170B](https://openairdocs.org/model/cessna-170b) (registry code 2072306) (OpenAirDocs) - Registry engine: [Continental C145 series](https://openairdocs.org/engine/continental-c145-series) (registry code 17012, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 25302 - Airframe hours: 4340 - Engines: Lycoming O-360-A1A 180 horsepower reciprocating - Damage: Substantial damage - Flight: Business, Part 91 - Registered owner: Victor G. Sifsof - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 1, 1996 - Departed: DLG, DILLINGHAM, AK ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 55; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: right; flight hours: 1,319 total, 750 in this make and model, 25 in the last 90 days, 11 in the last 30 days, 8 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 270° at 12 knots - Visibility: 20 statute miles - Lowest ceiling: none - Temperature: 48 °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 19960430008989A](https://openairdocs.org/incident/19960430008989A), Apr 30, 1996: Cessna 170B, Togiak, AK, Substantial damage. Right main wheel broke landing on gravel beach. Nosed over. Fatigue cracks rust and corroison on strut at break. 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.