NTSB Identification: MIA03LA070.
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Accident occurred Monday, February 24, 2003 in Sanford, FL
Probable Cause Approval Date: 06/02/2004
Aircraft: Cessna 172RG, registration: N5177R
Injuries: 2 Minor.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
Before the flight departed, hydraulic fluid was added to the landing gear hydraulic system. The certified flight instructor (CFI) reported that after takeoff the landing gear retracted without incident. The flight proceeded to the practice area where airwork was performed. The flight continued and when the landing gear was extended prior to performing additional airwork, it failed to extend. The emergency checklist was followed but failed to extend the landing gear. The flight returned to the departure airport and the flight crew contacted dispatch in an attempt to lower the landing gear which was unsuccessful. Additionally, the CFI attempted to manually extend the main landing gear but was unable. The flight returned for landing and with the nose landing gear extended and the main landing gear in trail, the main landing gear collapsed at touchdown. Examination of the airplane by an FAA Airworthiness inspector revealed the hand pump suction line assembly part number 2480001-23, was damaged. Hydraulic fluid covered the area. The line was retained for further examination. The damaged line was examined by the NTSB Materials Laboratory. Examination of the line revealed at least 8 transverse cuts in the tube section of the line adjacent to the end ferrule. A cut directly adjacent to the end ferrule penetrated the wall thickness and was slightly less than .03 inch wide. The sides of that cut were straight into the tube but the bottom of the cut had a curved surface progressing to a sharp bottom. The other cuts did not penetrate the wall thickness, and loss of metal at the cut locations appeared to be primarily from metal flow as opposed to being from grinding or cutting away material. There was no evidence that the edges of the ferrule or B-nut created the cuts in the tubing.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The intentional cutting of the hydraulic line by an unknown person resulting in the loss of hydraulic fluid and the inability of the pilot-in-command to extend and lock the main landing gear, and subsequent collapse of the main landing gear after touchdown. Full narrative available
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