Sunday, July 16, 2017

Cessna 140, N3625V: Accident occurred February 13, 2016 at Independence State Airport (7S5), Polk County, Oregon

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entity:

Federal Aviation Administration / Flight Standards District Office;  Hillsboro, Oregon

Aviation Accident Final Report - National Transportation Safety Board:https://app.ntsb.gov/pdf

Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms

Aviation Accident Data Summary - National Transportation Safety Board: https://app.ntsb.gov/pdf 

http://registry.faa.gov/N3625V 

NTSB Identification: WPR16LA068
14 CFR Part 91: General Aviation
Accident occurred Saturday, February 13, 2016 in Independence, OR
Probable Cause Approval Date: 05/01/2017
Aircraft: CESSNA 140, registration: N3625V
Injuries: 2 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The private pilot was landing the airplane on a dry, hard-surfaced runway. He stated that the approach and touchdown were normal. Just after touchdown, he felt “something similar to a bump,” and the airplane started to drift to the left. He thought that the airplane possibly had a flat tire and tried to compensate with rudder input, but the airplane continued drifting to the left, exited the left side of the runway, and ground looped, resulting in substantial damage to the right wing and fuselage.

An on-scene examination revealed that the left main landing gear axle had fractured, resulting in the separation of the wheel assembly. A detailed examination revealed that the axle was fractured near the inboard end, just outboard of the axle attachment flange. Portions of the fracture surface at the upper and lower sides of the axle had relatively smooth features oriented perpendicular to the outer surface, consistent with fatigue. The fatigue cracks initiated at a fillet corner at a change in the axle’s outer diameter. 

The manufacturer specified inspection intervals to check for cracks and corrosion of the main landing gear axle; however, the accident airplane’s maintenance logs were not located, and the airplane’s maintenance history could not be determined.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The failure of the left main landing gear wheel axle due to a fatigue crack.

On February 13, 2016, about 0930 Pacific standard time, a Cessna 140G airplane, N3625V, sustained substantial damage when the left main landing gear axle broke during landing and the airplane ground looped at the Independence State Airport, Independence, Oregon. The private pilot and one passenger were not injured. The airplane was owned by the pilot and operated as a personal, cross-country flight under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan had been filed for the flight.

In a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge, the pilot stated that the approach and touchdown were normal. Just after touchdown, he felt something similar to a bump, and the airplane started to drift to the left. He stated that he thought that he possibly had a flat tire and tried to compensate, but the airplane continued drifting to the left and exited the left side of the runway into the dirt and ground looped, sustaining substantial damage to the right wing and fuselage. 

A Federal Aviation Administration inspector from the Portland Flight Standards District Office was at the airport at the time of the accident and examined the airplane at the accident site. The examination revealed that the left main landing gear axle had fractured and the wheel assembly separated from the airplane. 

A detailed examination of the fractured axle by the NTSB materials laboratory revealed that the axle was fractured near the inboard end just outboard of the axle attachment flange. Portions of the fracture surface at the upper and lower sides of the axle had relatively smooth features oriented perpendicular to the outer surface, features consistent with fatigue. The fatigue cracks initiated at a fillet corner at a change in outer diameter for the axle. 

According to a representative for Cessna contacted by telephone, inspections of the main landing gear axle should be in accordance with Section 2A of the Maintenance Manual for the 100-series airplanes. The axles should be inspected for cracks and corrosion initially after 10 years or 4,000 hours and then at subsequent intervals of 3 years or 1,000 hours. The inspection consists of removing the wheel and completing a visual inspection. If any crack is suspected, an eddy current inspection is then required.

The airplane was manufactured in 1948. The owner/operator reported that the last annual inspection was completed about 7 months prior to the accident at a total airframe time of 6,314.5 hours. No airframe logbooks were located during the investigation, therefore it was not determined when the last inspection of the main landing gear axle occurred.

NTSB Identification: WPR16LA068 
14 CFR Part 91: General Aviation
Accident occurred Saturday, February 13, 2016 in Independence, OR
Aircraft: CESSNA 140, registration: N3625V
Injuries: 2 Uninjured.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

On February 13, 2016, about 1100 Pacific standard time, a Cessna 140G airplane, N3625V, sustained substantial damage when the left main landing gear axle broke during landing and the airplane ground looped at the Independence State Airport, Independence, Oregon. The private pilot and one passenger were not injured. The airplane was owned by the pilot and operated as a personal, cross-country flight under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan had been filed for the flight.

In a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge, the pilot stated that the approach and touchdown were normal. Just after touchdown, he felt something similar to a bump, and the airplane started to drift to the left. He stated that he thought that he possibly had a flat tire and tried to compensate, but the airplane continued drifting to the left and exited the left side of the runway into the dirt and ground looped, sustaining substantial damage to the right wing and fuselage. 

A Federal Aviation Administration inspector from the Portland Flight Standards District Office was at the airport at the time of the accident and examined the airplane at the accident site. The examination revealed that the left main landing gear axle had fractured and the wheel assembly separated from the airplane. A detailed examination of the fractured axle by the NTSB materials laboratory is pending.

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