Port St. Lucie, FL, USA
N51KK
Krejci S-51D
The airplane was observed on the takeoff roll by several witnesses. The engine was heard making a sound described as similar to a pop, slight burp, stumbling engine, slight miss, or a sound similar to dropping a cylinder like a belch. The tail wheel was observed to come off the ground and the engine was heard to make a missing sound and then smoothed out. The airplane became airborne and was observed to initiate a right turn followed by a steep turn back to the left estimated at about a 45-degree angle of bank. Both wing tips were visible to the witnesses. The airplane was at about 200 to 250 feet when it appeared to encounter a stall. It looked like the pilot initiated a recovery. The nose came up and the wings started to level. The airplane disappeared from view behind some tress and was heard to impact the terrain. Examination of the engine assembly revealed a hole in the vicinity of the No. 7 cylinder. The rocker cover was removed and the rocker arm for the exhaust valve was lying at an angle. The stud for the rocker arm was broken. A valve rocker retaining nut found at the crash site matched the broken end of the stud.
On February 26, 2002, about 1606 eastern standard time, a Krejci S-51D experimental airplane, N51KK, registered to a private owner, operating as a 14 CFR Part 91 personal flight, crashed while maneuvering after takeoff from Treasure Coast Airpark (FL37) Port St. Lucie, Florida. Visual meteorological conditions prevailed and no flight plan was filed. The airplane sustained substantial damage. The airline transport pilot was fatally injured. The flight was originating at the time of the accident. A witness who was a demo pilot for the S-51D, and a friend of the deceased pilot stated the pilot departed FL37 to the west. The landing gear was observed to retract. The airplane was observed to climb between 200 to 300 feet AGL and made a steep crosswind departure. The angle of bank was estimated between 45 to 50 degrees. The airplane entered into an accelerated stall. The left wing dropped and the nose pitched down. There was no change in engine power heard. The airplane was observed to recover from the stall and encountered a secondary stall. The airplane collided with the ground in a wings level, tail low condition. The witness stated the stall speed for the airplane in a clean configuration (gear and flaps up) is 80 mph and in the dirty configuration (gear and flaps down) is 70 mph. Other witnesses stated they heard the S-51D start up. They observed the airplane on the takeoff roll. They all heard a sound from the engine described as a " pop," "slight burp," "stumbling engine," "a slight miss" or "an engine sound similar to dropping a cylinder, like a belch." The sound smoothed out and the airplane continued its takeoff roll with sufficient runway remaining to abort the takeoff. "The tail came off the ground, and the engine belched again and then smoothed out." The airplane rotated, the landing gear came up, and the nose was observed to drop a little. The witnesses stated the airplane was observed in a right turn followed by a steep left turn estimated about 40-degrees angle of bank and both wing tips were observed. One witness stated, " the airplane was about 200 to 250 feet when it encountered an accelerated stall. The left wing dropped and the nose pitched up. The airplane was observed was observed to initiate a recovery, the nose came up and the wings started to level." The airplane disappeared from view behind the trees and he heard a "thud" sound when the airplane collided with the ground. A neighbor of the deceased pilot who witnessed the accident had previously contacted the FAA on April 13, 2001, stating the deceased pilot and another pilot constantly created a hazard and a nuisance in the vicinity of his home. He alleged that N51KK was being flown in a careless and reckless manner, and he was concerned that these actions would eventually result in an aircraft accident. The allegation was investigated by the FAA and the pilot was verbally warned. Review of information on file with the FAA Airman's Certification Division, Oklahoma City, Oklahoma, revealed the pilot was issued an airline transport pilot certificate on April 19, 2000, with ratings for airplane multiengine land/airline transport pilot, airplane single engine land/commercial pilot and instrument airplane. The pilot held an airline transport pilot type rating in the Boeing 707, 720, 727, 757, and 767. In addition he held a flight engineer certificate with a rating for reciprocating engine powered. The pilot held a second class medical certificate issued on August 14, 2000, with the restriction must wear lenses for distant vision and posses glasses for near vision. The pilot indicated on his application for the second class medical certificate that he had accumulated 19, 300 total flight hours. The pilots last recorded biennial flight review was June 29, 2000. The pilots last recorded entry in the aircraft record indicates that he had logged 135.7 total hours in the S-51D. Review of the engine logbook revealed the last recorded annual inspection was conducted on June 1, 2001. According to the deceased pilot's wife, her husband blew the first engine in N51KK on July 20, 2001. A friend flew to Wisconsin to remove the engine around July 27, 2001. A new engine was obtained and built up. The engine was transported back to Wisconsin and installed on N51KK and the airplane was flown on September 27, 2001. According to the pilot's wife the old engine had accumulated 102.1 hours and there was about 33.6 hours on the new engine. Review of the engine logbook does not reflect that the engine was removed and a new engine was installed. The nearest weather reporting facility at the time of the accident was Fort Pierce, Florida. The 1532 surface weather observation was: 6,000 scattered, visibility 10 miles, temperature 75 degrees Fahrenheit, dew point temperature 55 degrees Fahrenheit, wind 240-degrees at 6 knots, and altimeter 29.97. Visual meteorological conditions prevailed at the time of the accident. The wreckage of N51KK was located in a cow pasture to the west of a dead end road in the vicinity of Twin Beach Terrace, Port St. Lucie, Florida. The scene was processed by law enforcement personnel and the wreckage was released for recovery only to a friend of the family. The wreckage was subsequently relocated to the hangar of the deceased pilot. The wreckage of N51KK was examined in the deceased pilot's hangar by an FAA Aviation Safety Inspector. The inspector stated, "The aircraft appears to have initially impacted in a tail low attitude with a fair amount of vertical velocity. The fuselage is broken aft of the cockpit, with tear damage consistent with tail first impact. The tail section is drooped aft of the torn area with the fuselage resting on the radiator. There is torn skin and pulled rivets at the stress point. The ear type counterbalance weights on each elevator are torn loose in a downward direction, as are the aileron weights. The right aileron is separated from the wing and the right flap is partially separated. The rudder is torn loose at the lower hinge point with the spar bent aft at the center hinge point and it is not connected to the control tube. Each elevator is loose and moves independently of the other. Neither could be moved using the cockpit controls. Movement of the stick in either cockpit did not move the ailerons. The push pull tube was probably broken when the wings bent at the joint. The left rudder pedal was jammed by cockpit damage and could not be moved. The wings are still attached to the fuselage and exhibit very little leading edge damage. They lie fairly flat and appear to be broken at the dihedral joint in the fuselage. The seat belt and shoulder harness attachments were intact and the pilot appears to be wearing the belt and harness in the post crash photos. The canopy is off the fuselage and appears to have separated from the aircraft near the point of initial impact. The aircraft has electronic instruments installed and electrical power could not be applied to gain a current hour meter reading. " (For additional information see FAA Aviation Safety Inspector Statement an attachment to this report.) A friend of the family handed a valve rocker-retaining nut containing a portion of a broken rocker stud to the FAA inspector upon his arrival at the deceased pilot's hangar. The friend stated the nut had been recovered from the crash site when the wreckage was moved and it was in the same area as other engine compartment debris. The FAA inspector stated, "a visual inspection of the engine revealed a hole in the rocker cover, approximately 1 inch wide by about 2 inches long. The hole was over the area of the above mentioned rocker retainer nut, and exhibited exit hole characteristics. This hole was located over the number 7 cylinder, or the second from the front on the right side. The rocker cover was removed and the rocker arm for the exhaust valve on this cylinder was seen to be loose, lying at an angle, not contacting the valve stem or the pushrod. The stud for this rocker was broken, and the broken end matched that of the portion of the broken stud in the nut. This render the exhaust valve for this cylinder inoperative. This would be problematic at a high takeoff power setting as the combustion gasses would not be able to escape the cylinder until the intake valve opened again, at which time the expanding hot gasses would enter the induction system, causing misfire and a partial power loss. The other rocker cover was removed and all other valve operating mechanism was inspected and appeared to be normal." (For additional information see FAA Aviation Safety Inspector Statement an attachment to this report.) Dr.Charles A. Diggs, Associate Medical Examiner, District 19, Port St. Lucie, Florida, conducted postmortem examination of the pilot on February 27, 2002. The cause of death was multiple injuries due to blunt trauma. Postmortem toxicology of specimens from the pilot was performed by the Forensic Toxicology Research Section, Federal Aviation Administration, Oklahoma City, Oklahoma. The results were negative for basic, acidic, and neutral drugs. The wreckage of N51KK was released for recovery only to a friend of the family at the family request since the airplane was not insured on February 27, 2002. A copy of the wreckage release was given to the widow of the deceased. The engine logbook and aircraft logbook were released to the deceased pilots wife on March 12, 2002.
The pilots failure to maintain airspeed while maneuvering in an attempt to return to landing area (Emergency/ departure airport.) This resulted in an inadvertent stall and subsequent in-flight collision with terrain. Factor to the accident was a partial loss of engine power due to a failed exhaust valve.
Source: NTSB Aviation Accident Database
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