HOUSTON, TX, USA
N24893
CESSNA 152
ON THE FLIGHT PRIOR TO THE ACCIDENT FLIGHT, AN INSTRUCTOR AND A STUDENT HAD EXECUTED A SUCCESSFUL FORCED LANDING TO THE AIRPORT FOLLOWING A PARTIAL POWER LOSS. AFTER LANDING, THE INSTRUCTOR NOTED AN RPM DROP ON THE MAGS OF 1000 LEFT AND 500 RIGHT AND THAT THE ENGINE WAS RUNNING ROUGH AT IDLE ON BOTH MAGS. HE REPORTED THE LANDING AND ENGINE PROBLEM TO FBO PERSONNEL MANNING THE FRONT DESK. SHORTLY THEREAFTER, THE AIRPLANE WAS SIGNED OUT TO A 17-YEAR-OLD SOLO STUDENT PILOT. WITNESSES SAID THEY HEARD THE ENGINE RUNNING ROUGH AND TWO SAID IT QUIT. THEY ALSO STATED THAT THE AIRPLANE WAS MANEUVERING AT ABOUT 100 FEET TOWARD A DIRT ROAD WHEN IT NOSED DOWN WHILE IN A LEFT BANK. THE ENGINE EXAM REVEALED A CHAFED PLUG LEAD ROUTED AROUND A PRIMER LINE AND FOULED PLUGS ON THE MAJORITY OF THE CYLINDERS. PRIOR TO GOING OUT TO THE AIRPLANE, THE STUDENT WAS INSTRUCTED BY THE DISPATCHER AND AN UNIDENTIFIED INSTRUCTOR TO DO A 'GOOD ENGINE RUN UP' AND LEAN OUT THE MIXTURE TO 'CLEAR THE PLUGS.'
HISTORY OF FLIGHT On August 4, 1993, at approximately 1935 central daylight time, a Cessna 152, N24893, was destroyed when it impacted the ground near the Weiser Airport, in Houston, Texas, following a loss of control during a forced landing. The forced landing was being attempted following an engine power loss. The airplane, owned and operated by a flight school, and flown by a student pilot, was on a local solo instructional flight. There was no flight plan filed and visual meteorological conditions. The pilot, the sole occupant, received fatal injuries. According to witnesses at the airport, the pilot had been performing touch and go landing practice earlier in the flight and had then departed the pattern. Some time later, the airplane was observed maneuvering at low altitude about 1/2 mile south of the end of runway 09 at the departure airport. The witnesses stated they first noticed the airplane when it was at an altitude of about 100 feet AGL. Two of the witnesses stated they thought that the engine quit and one stated that he thought it was running rough. One stated he thought the airplane was flying "relatively slow." They stated that the airplane entered a left bank as if to line up on a road. During the bank, the nose fell through and the airplane impacted the ground adjacent to a north south road inside an industrial complex. WITNESSES Statements were obtained from five eyewitnesses. In addition, statements were also obtained from the CFI who had flown the accident airplane on a flight immediately before the accident, the student pilot's father, and one anonymously. PERSONNEL INFORMATION Interviews with the student's instructors indicated that he was a "good" student and proficient in forced landings and stall recovery. AIRCRAFT INFORMATION A review of the airplane's maintenance records did not reveal any discrepancies that would have affected the airworthiness. The airplane was topped off with 100LL aviation fuel immediately prior to the accident flight. The airplane had developed an engine problem during the flight that preceded the accident. According to the CFI that was flying it at the time, the airplane experienced a power loss while performing touch and go landings. He stated that during the initial climb after a landing, the RPM dropped from 2,350 down to 2,050 RPM. He assumed control of the airplane from his student and began maneuvering to execute a forced landing back at the airport. He stated that the airplane would not sustain level flight and the best he could do was a descent of about 250 feet per minute. He further stated that during the descent, he ran through the emergency checklist. He stated that application of carburetor heat produced a further reduction in RPM as did leaning the mixture. He left the power on full throttle and was able to land on runway 27 at the Weiser Air Park. The instructor said that once on the ground, he taxied to the pad and checked the magnetos. He observed a 1000 RPM drop on the left and a 500 RPM drop on the right. He also stated that the engine was running rough at idle with both magnetos on. He further stated that the power loss had "come on so suddenly and quietly" that his student did not realize it until the instructor pointed it out. After the run up, the instructor taxied the airplane to the maintenance hangar; however, there was another airplane at the hangar and he could not leave a second airplane as it would block the taxiway and other hangars. He subsequently taxied it back to the line and immediately informed Mr. Noel Shannon, who was on the front desk at the flight school. He stated that he informed Mr. Shannon that he had made a forced landing and there was a "major" problem with the engine and related the RPM loss and advised him that the airplane needed to be repaired. A few minutes later, the instructor saw the airplane being refueled by line personnel and assumed they were topping it off prior to moving it to maintenance. He further stated that he was shocked to learn a few minutes later that the airplane had been dispatched with a solo student. According to information received from the instructor and the FAA, the airplane was signed out to the accident pilot shortly after the instructor had discussed the power loss with Mr. Shannon, but prior to any maintenance personnel looking at the engine. The student was instructed to perform a "good run up" and lean out the mixture to clean the spark plugs and that the engine should be "all right." He was instructed to do this by Mr. Shannon and another unidentified flight instructor. COMMUNICATIONS There were no distress calls on any of the area FAA frequencies and no one recalled hearing the pilot report any problem over the UNICOM frequency. WRECKAGE AND IMPACT INFORMATION The airplane impacted in a brush field, adjacent to a dirt service road on a measured heading of 325 degrees. Three imprints in the ground corresponded to the main and nose landing gear. From the center imprint, a four to five inch deep trench extended to the main wreckage which was 16.5 feet from the point of initial impact. The leading edges of both wings were compression damaged to a depth of about 8 inches, but no corresponding ground scars were found. All of the flight controls remained in place and attached and continuity was established to each. The engine was found displaced evenly aft and some of the accessories had penetrated through the fire wall. The propeller was found separated from the engine flange. One propeller blade was bent and neither exhibited any twist or chordwise striations. The pilot's seat remained anchored to the floor; however, the seat was deformed as were the seat tracks. The seat belt was found latched, but the shoulder harness attachment was not attached. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy and toxicology testing were ordered. The autopsy was performed by the Harris County Medical Examiner's Office at Houston, Texas. The toxicology studies were completed by the FAA Civil Aeromedical Institute. The toxicology studies indicated a 11.000 mg/dl of Ethanol in the urine. This level was below the FAA allowed limits and it was reported that it could have been from postmortem production. FIRE The witnesses stated that the fire erupted immediately after impact and appeared to have started in the area of the engine compartment. The exact ignition source was not determined. TESTS AND RESEARCH Engine Disassembly and Examination: The engine was torn down and examined at Wilson Aircraft in Houston, on August 12, 1993. The FAA was in attendance at the examination. The engine log books indicated that it had the same total time as the airframe and had accumulated a total of 2,470.5 hours since the last major overhaul. The engine had been extensively fire damaged. The magnetos were destroyed. It was found that the number 3 cylinder lower spark plug lead had been routed around the primer line and had abraded through the insulation to the wire. In addition, several of the spark plugs were found fouled and/or sooted. For a complete discussion of the tear down, see the attached report. ADDITIONAL INFORMATION Wreckage Release: The wreckage was verbally released to the owner's representative after the engine tear down on August 12, 1993. All of the retained aircraft records were returned during the investigation.
COMPANY MANAGEMENT'S DISPATCH OF AN AIRPLANE WITH KNOWN DEFICIENCIES, THEIR FAILURE TO CORRECT THE DEFICIENCIES, AND THE STUDENT PILOT'S INADVERTENT ENTRY INTO A STALL. FACTORS WHICH CONTRIBUTED TO THE ACCIDENT WERE: CHAFED WIRING, FOULED SPARK PLUGS, A MAGNETO INDUCED PARTIAL POWER LOSS, AND AN UNIDENTIFIED INSTRUCTOR'S FAILURE TO PROVIDE PROPER ASSISTANCE TO THE STUDENT PILOT.
Source: NTSB Aviation Accident Database
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