On March 3, 2001, about 1324 eastern standard time, a Cessna 172L, N3802Q, owned by Leasing Technology, Inc., leased and registered to a private individual, experienced an in-flight failure of the yoke weld assembly and a subsequent hard landing at the Fort Lauderdale Executive Airport, Fort Lauderdale, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 instructional flight. The airplane was substantially damaged and the certified flight instructor (CFI) and student pilot were not injured. The flight originated about 1145 from the Fort Lauderdale Executive Airport. The student stated that after departure he performed airwork then returned for landing; the CFI was 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. Examination of the airplane revealed impact damage to the firewall (See photograph 01); compression wrinkles were noted in the pilot's and co-pilots cockpit area floor skin, on the bottom skins of both wings at wing station 100.5, and on the right side at and aft of the firewall in line with refueling step. The belly skin and structure was damaged from the firewall aft to fuselage station 16.66. No continuity existed between the left and right control yokes (elevator control input in one does not move other side). Removal of the inspection plate attached to the fuselage bottom skin beneath the vertical tube of the yoke weld assembly revealed corrosion on the interior surface of inspection plate (See photograph 02). The vertical tube of the yoke weld assembly (P/N 0511782-17), was found fractured approximately 5.5 inches up from the bottom (See photograph 05); that point was also located was approximately 5/32 inch above the yoke pivot point (See photographs 03 and 04). The interior of the separated lower portion of the vertical tube appears filled with unknown substance which was retained for analysis (See photograph 06). 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 (See photograph 07). 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 (See photograph 07); 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. Debris from the separated upper portion of yoke weld assembly was recovered when the separated lower piece of the vertical tube was removed from the airplane (See photograph 08). Corrosion was also noted on the pilots and copilots gusset areas of the yoke weld assembly (See photographs 09 and 10). The two sections of the yoke weld assembly were removed and retained for further examination by Cessna Aircraft Company. Debris consisting of 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 pieces of the yoke weld assembly was performed by Cessna Aircraft Company, Material and Process Engineering (M & P), located in Wichita, Kansas. The report indicated that extensive corrosion was noted on exterior areas and also interior areas of the tubing of the yoke. 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 debris which was found in the upper and lower separated portion of the vertical tube of the yoke weld assembly was also examined by Cessna Aircraft Company M & P. The results of the analysis of the debris found in the upper portion of the yoke weld assembly revealed no significant organic material was identified; "there is an abundance of iron oxide (Fe2O3), which could be attributed to the corrosion of steel." The results of the analysis of the debris found in the lower portion of the yoke weld assembly revealed, "The debris was found to consist mainly of iron and oxygen, with smaller amounts of chlorine, carbon, sodium, silicon and sulfur...." The reports from Cessna are an attachment to this report. The airplane was determined to be in a hangar on Freeport, Bahamas, on September 14, 1999, when hurricane Floyd passed north of the island. A copy of Hurricane Floyd Tracking Map is an attachment to this report. One of the co-owners of the airplane reported that as a result of the hurricane, the airplane was partially submerged in salt water up to the battery. The airplane was declared a "total write-off", and the owners were paid for the loss of the airplane. One of the owners of the airplane submitted to the FAA a "Triennial Aircraft Registration Report" dated November 1, 1999, indicating that the airplane was "...destroyed/scrapped." The form was mailed to the FAA located in Oklahoma City, Oklahoma; the airplane was deregistered by the FAA on January 10, 2000. A statement from one of the owners of the airplane who owned it during Hurricane Floyd and a NTSB Record of Conversation with the co-owner are an attachment to this report. Review of photographs provided by the insurance adjuster who examined the airplane in the Bahamas following the hurricane revealed evidence of a water line on the exterior skin of the pilot's door up to the outside door handle (See photograph 11). Following the hurricane, the airplane was put out for bidding by the insurance company to be sold "as-is & where is." The paperwork from the insurance company placing the airplane up for bidding indicates in part "aircraft was submerged in 4-6 feet of salt water resulting from hurricane Floyd on 09-14-99." A bid by Wentworth Aircraft, Inc., of Minneapolis, Minnesota, was accepted on December 13, 1999. The airplane was then sold to Aero-Star Connection on an unknown date, and sold again to the current owner of the airplane, Leasing Technology, Inc., on June 1, 2000. The airplane was registered with the FAA in the lessee's name on July 19, 2000, with the same registration originally assigned. According to the lessee of the airplane, the person who did the prepurchase inspection was also the seller of the airplane. A copy of the paperwork provided by the insurance adjuster pertaining to selling of the airplane following the hurricane and the acceptance of the bid by Wentworth Aircraft, Inc., is an attachment to this report. Review of the aircraft logbooks that contained entries from a test flight dated July 7, 1971, to the last entry (100-Hour/annual inspection) dated February 5, 2001, revealed no entry indicating replacement of the yoke weld assembly. The entry for the last 100-Hour inspection indicates in part that the airplane was inspected using the Cessna Service Manual, all inspection covers were removed, and, "...sprayed with corrosion X anticorrosion treatment" The airplane had accumulated approximately 12 hours at the time of the accident since the 100-Hour/annual inspections were signed off. No entries were noted between September 18, 1998, (100-Hour/Annual Inspection) and February 9, 2000, (annual inspection). Additionally, there was no entry in the maintenance records indicating that the airplane was partially submerged in salt water; there is no requirement to make such an entry. Excerpts from the maintenance records are an attachment to this report. Review of the Service Manual revealed that 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. 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 airplane minus the retained fractured yoke weld assembly was released to the lessee of the airplane on March 8, 2001. The retained yoke weld assembly was released to claims representative Scott McGinnis, of Universal Loss Management, Inc., on August 2, 2001.