NTSB Identification: MIA01LA094.
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Accident occurred Saturday, March 03, 2001 in Fort Lauderdale, FL
Probable Cause Approval Date: 11/06/2001
Aircraft: Cessna 172L, registration: N3802Q
Injuries: 2 Uninjured.
NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
After takeoff the student pilot/lessee of the airplane performed airwork with a CFI on-board and returned for landing with the CFI flying the airplane. The CFI stated that the flight entered the traffic pattern to land on runway 26, and while over the runway, "there all of a sudden was no more controllability of the plane by the yoke." He asked the student to pull on the yoke but again there was no response. The airplane touched down on all three landing gears then bounced, then after the second touchdown, the CFI applied rudder input and the airplane departed the runway onto grass. Evidence of a hard landing was noted. The yoke weld assembly was found completely fractured approximately 5.5 inches up from the bottom; that point was also located was approximately 5/32 inch above the yoke pivot point. Extensive corrosion from the fracture location down approximately 3 inches was noted on the forward and left sides of the exterior surface of lower separated piece of the yoke weld assembly when viewed as installed in the airplane. Extensive corrosion was also noted on the lower end of the yoke weld assembly which contains a rod end bearing and is the attach point for the elevator push/pull tube; the rod end bearing was not free to move. No drain hole was found in the separated lower portion of the vertical tube of yoke weld assembly. Corrosion was also noted on the pilots and copilots gusset areas of the yoke weld assembly. The interior of the separated lower portion of the vertical tube appears filled with a substance mainly comprised of iron and oxygen. Debris from the separated upper portion of yoke weld assembly did not contain significant inorganic material; an abundance of iron oxide was noted. Small leaves, metal shavings, fasteners, grass, and dirt was found on interior surface of lower fuselage skin in cockpit area; some of the same type of debris (small leaves, grass, and dirt) was found inside the battery box. Mold was found on the cockpit side of the firewall insulation blanket (white and green powder). Examination of the two sections of the yoke weld assembly by personnel from Cessna Aircraft Company indicate that the wall thickness near the separation point was reduced to near zero. The material was correct and the hardness tests of the tubing revealed they were greater than the minimum specified values. Evidence of water marks were noted on the upper portion of the separated vertical tube of the yoke weld assembly. The airplane was determined to be partially submerged by salt water as a result of hurricane Floyd in September 1999, the water level was reportedly up to the battery. The airplane was then sold as salvage; the then owner reported to the FAA that the airplane was ..."destroyed/scrapped." The airplane was re-registered with the FAA; there was no entry in the maintenance records indicating the airplane was partially submerged; none was required. The airplane was inspected last in accordance with an annual/100-Hour inspection using the Service Manual checklist. The Service Manual indicates the 50-Hour, 100-Hour, 200-Hour, and special inspection items comprise a complete inspection of the airplane. The control "U" is listed to be inspected in the 200-Hour column. The airplane had accumulated approximately 12 hours since then at the time of the accident. According to Cessna Aircraft Company personnel, there is no inspection listed in the airplane service manual required when an airplane becomes partially submerged or submerged in salt water. Additionally, review of the Advisory Circulars (AC)'s revealed no inspection criteria or advise on what to do with respect to a salt water partially submerged or submerged aircraft.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The total failure of the yoke weld assembly due to corrosion resulting in the inability of the flight crew to maintain elevator control of the airplane. Additionally, inadequate annual inspection of the airplane by other maintenance personnel for failure to identfiy extensive corrosion of the yoke. Findings in the investigation were: 1) The airplane was partially submerged in salt water as a result of hurricane Floyd in September 1999, 2) The Advisory Circulars do not identify inspection procedures what to do in case an airplane is sumberged or partially submerged in salt water, and 3) The airplane manufacturer does not have inspection procedures when an airplane is submerged or partially submerged in salt water. Full narrative available
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