# NTSB ANC02LA099: Maule M-7-235, N897M, Palmer, AK, August 19, 2002 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 19, 2002, 09:00 local (17:00 UTC) - Place: Palmer, AK - Coordinates: 61.583332, -149.093048 - Nearby events: https://openairdocs.org/map.md?lat=61.5833&lon=-149.0930&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report June 25, 2003 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: Anchorage FSDO - NTSB case key (mKey): 55531 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC02LA099 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/55531/pdf - Page: https://openairdocs.org/ntsb/ANC02LA099 ## Probable cause The fracture of the right main landing gear axle during landing roll. Factors associated with the accident were corrosion of the landing gear axle, failure of company maintenance personnel to adequately inspect the axle and detect the corrosion, and rough and uneven terrain. ## 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,axle - fractured (cause) - maintenance,inspection - inadequate, company maintenance personnel (contributing factor) - landing gear,axle - corroded (contributing factor) - terrain condition - rough/uneven (contributing factor) - Main gear collapsed, landing - roll ## Analysis The commercial pilot was landing the tundra-tire equipped airplane atop a mountain ridge. During the landing roll on the rough and uneven terrain, the right main landing gear axle broke allowing the right wheel to separate from the airplane. The airplane pivoted to the right, and the left wing struck the ground. The airplane sustained substantial damage to the wings and fuselage. Following retrieval of the airplane, an FAA airworthiness inspector examined the broken axle. He reported that a visual inspection of the broken landing gear axle revealed that the fracture traveled through a drilled hole in the axle. The FAA inspector said that the drilled hole is used when the airplane has a wheel/ski kit installed. He added that there was a substantial amount of corrosion and rust within and around the fracture surface. The operator reported that the time in service of the failed landing gear axle was about 2,500 hours, and the time since inspection was about 1,800 hours. ## Factual narrative On August 19, 2002, about 0900 Alaska daylight time, a tundra-tire equipped Maule M-7-235 airplane, N897M, sustained substantial damage when the right main landing gear axle broke during landing roll on rough and uneven terrain on a mountain ridge top, located about 15 miles east of Palmer, Alaska. The airplane was being operated as a visual flight rules (VFR) on-demand charter flight under Title 14, CFR Part 135, when the accident occurred. The airplane was operated by Grasshopper Aviation, Wasilla, Alaska. The certificated commercial pilot, and the two passengers, were not injured. Visual meteorological conditions prevailed, and company flight following procedures were in effect. The flight originated at the Palmer Airport, Palmer, about 0840. During a telephone conversation with the National Transportation Safety Board investigator-in-charge on August 19, the pilot reported that he was landing to the north on a mountain ridge top. He said that during the landing roll, the right main landing gear axle broke allowing the right wheel to separate from the airplane. The airplane pivoted to the right, and the left wing struck the ground. The airplane sustained substantial damage to the wings and fuselage. The airplane was retrieved from the accident site and transported to Palmer by company and insurance personnel. A Federal Aviation Administration (FAA) airworthiness inspector, Anchorage Flight Standards District Office, traveled to the operator's maintenance facility, and examined the fractured landing gear axle. The FAA inspector reported that the operator utilized a set of Schneider Fixed Penetration Wheel/Skis, model SWS-4000, during the winter time. The initial installation of the wheel/ski kit was accomplished under the FAA's Major Repair and Alteration process, FAA Form 337. The FAA inspector added that during the initial wheel/ski kit installation process, a 3/8-inch hole was drilled through the axle. The FAA inspector said that a visual inspection of the fractured landing gear axle revealed the fracture trail traveled through the drilled hole in the axle. He added that there was a substantial amount of corrosion and rust within and around the fracture surface. According to the NTSB Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) submitted by the operator, the airplane had accumulated about 2,504.5 hours in service. The operator noted that the time in service of the failed landing gear axle was about 2,500 hours in service, and the time since inspection was about 1,800 hours. ## Aircraft - Registration: [N897M](https://openairdocs.org/aircraft/N897M), registered now, S/N 4064C, built 1989 (OpenAirDocs) - Reported make and model: Maule M-7-235 - Registry model: [Maule M-7-260](https://openairdocs.org/model/maule-m-7-260) (registry code 5460111) (OpenAirDocs) - Registry engine: [Lycoming 0-540 series](https://openairdocs.org/engine/lycoming-0-540-series) (registry code 41532, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 4064C - Airframe hours: 2484.5 - Engines: Lycoming O-540 235 horsepower reciprocating - Damage: Substantial damage - Flight: Part 135 - Registered owner: Glenn, David Hamilton - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, August 12, 2002, 20 hours before - Departed: PAQ, Palmer, AK - Destination: PAQ, Palmer, AK - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 58; injuries: none; commercial; airplane ratings: single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; last flight review July 27, 2001; seat: left; flight hours: 3,500 total, 2,500 in this make and model, 3,500 as pilot in command, 150 in the last 90 days, 75 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 300° at 10 knots, gusting 15 - Visibility: 10 statute miles - Lowest ceiling: 3,000 ft overcast - Temperature: 45 °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 20020819024619A](https://openairdocs.org/incident/20020819024619A), Aug 19, 2002: Maule M7235, Palmer, AK, Substantial damage. (-23) On August 19, 2002, at approximately 0830, the pilot on a FAR part 135 flight with two passengers landed on an unimproved runway located at the right… ## Other investigations on N897M (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 ANC96LA130](https://openairdocs.org/ntsb/ANC96LA130), Aug 24, 1996: Maule M-7 (N897M), Palmer, AK, substantial damage. Probable cause: The pilot's selection of an unsuitable landing area. 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.