On April 5, 2011, about 2130 eastern daylight time, a Cessna 172RG, N5284V, was substantially damaged when the main landing gear collapsed during the landing roll at Okeechobee County Airport (OBE), Okeechobee, Florida. Both the certificated flight instructor (CFI) and the private pilot were not injured. The aircraft was owned and operated by the CFI under the provisions of 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated from La Belle Municipal Airport (X14), La Belle, Florida, at 2000.

According to the private pilot, seated in the left seat, the purpose of the flight was to receive a biennial flight review from the CFI. He extended the landing gear on downwind, saw the green landing gear indicator light, felt the vibrations and heard the sounds associated with the landing gear extension. They continued onto the base and final leg of the traffic pattern, and landed the airplane. The landing "felt like normal;" however, the empennage could be heard scraping on the runway.

According to the CFI, seated in the right seat, they entered the left downwind leg of the traffic pattern to land on runway 23. The CFI was reading the Before Landing checklist and the private pilot extended the landing gear. The CFI put his hand on the landing gear handle to verify the landing gear was down, given that he could not see the green light from where he was sitting. When they turned to the base leg of the traffic pattern, the private pilot selected one notch of flaps, which correlated to 10 degrees, then a second notch of flaps, which correlated to 20 degrees, on the final leg of the traffic pattern. The landing felt "normal," then the main landing gear collapsed. The nose landing gear remained extended; the airplane veered left, and came to rest at the edge of the runway. At no point did the CFI hear the landing gear warning horn during the accident sequence.

A Federal Aviation Administration (FAA) inspector examined the airplane following the accident. According to the inspector, there were tire marks on the runway that were approximately 5 to 6 feet wide, and then they narrowed to 2 to 3 feet wide for the remainder of the marks leading to the airplane. According to the Cessna 172RG Information Manual, the distance between the two main landing gear tires was 8 feet 6 inches. The airplane incurred substantial damage to the left horizontal stabilizer during the accident sequence.

According to FAA records, the CFI held an airline transport pilot certificate for airplane multiengine land with commercial pilot privileges with ratings for airplane single-engine land, glider, and rotorcraft-helicopter. He also held a flight instructor certificate for single-engine and multiengine airplane, instrument airplane, and glider. In addition, he was an airframe and powerplant mechanic with inspection authorization. His most recent second-class medical certificate was issued in June 2010, and at that time, he reported 15,000 hours of total flight experience.

According to FAA records, the certificate rated student held a private pilot certificate with ratings for airplane single-engine land and rotorcraft-helicopter. His most recent FAA third-class medical certificate was issued on August 8, 2008. He reported 199 hours of total flight time, of which, 7 hours were in the same make and model as the accident airplane.

According to FAA records, the airplane was manufactured in 1980, and registered to the CFI in 2008. It was a four-seat, high-wing, retractable gear airplane that was equipped with a Lycoming O-360-F1A6 series engine. The most recent annual inspection was completed on September 18, 2010, at 9,007.2 total airplane hours. In the maintenance logbook entry for the most recent annual inspection, the CFI/mechanic indicated "normal gear operation and emerg[ency] gear extension OK." The CFI/owner was unable to produce the maintenance logbooks for the airplane, but was able to provide copies of the two most recent annual inspections.

A postaccident examination of the landing gear system was performed and the landing gear, power pack, and emergency landing gear extension, were operated several times utilizing the hydraulic/electric extension and the manual extension. During the examination, no grinding noise was observed and the main landing gear operated with no anomalies noted when the Pilot Operating Handbook procedures were utilized. Further examination revealed that the landing gear warning horn did not operate, but the landing gear indicator light operated with no anomalies.

A review of the airplane's Pilot Operating Handbook revealed that the landing gear lever and the landing gear indicator light were located on the lower portion of the switch and control panel to the left of the throttle. The landing gear was an electrically actuated, hydraulically accumulated system. The gear warning system was comprised of two lights; a green light to indicate the gear is down and in the locked position and an amber light which would indicate that the landing gear is in the up position. The landing system was also comprised of an audible warning horn which would emit and audible tone through the speaker to indicate that the gear was not in the appropriate position. Also, depending on the side of the airplane the pilot was seated, the associated main landing gear would be visible out the side window. According to manufacture guidance, the audible warning was to sound when either the manifold pressure was reduced below 12 inches or the flaps were extended beyond 20 degrees and the landing gear was retracted. The manual gear extension utilized a handle, located between the two front seats, that when the handle is extended, the pilot would manually move the handle in an upward and downward motion providing manual hydraulic pressure to extend the landing gear to the down position. In addition, in review of the Before Landing checklist, after selecting the landing gear down position with the landing gear selector, it stated to check the landing gear by observing the main landing gear in the down position and visually checking that the green indicator light is illuminated.