NTSB Factual Report

HISTORY OF FLIGHT

On May 30, 2009, about 1044 eastern daylight time (EDT), a Cessna 172M, N12151, was substantially damaged following a loss of engine power and a subsequent forced landing near Sarasota, Florida. The pilot and the pilot-rated co-owner/passenger received minor injuries. The personal flight was operated under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed for the flight, and no flight plan was filed.

According to the pilot, he performed a preflight inspection of the airplane using the airplane's checklist, and nothing unusual was noted. The preflight included a visual inspection of each fuel tank. The pilot stated that the left fuel tank was approximately one-half full, and the right tank was approximately three-quarters full. For the flight, the pilot was seated in the left seat, and the co-owner/passenger was seated in the right seat. The engine started normally, and the engine run-up was normal. The airplane departed Sarasota/Bradenton International Airport (SRQ), Sarasota/Bradenton, Florida about 1000, and flew to Venice Municipal Airport (VNC), Venice, Florida, located about 20 miles south of SRQ. The pilot performed two touch-and-go landings at VNC, and then initiated a return to SRQ. When the airplane was cruising at an altitude of 1,100 feet above mean sea level (msl), and still several miles from SRQ, the engine started to run rough, and then completely lost power. The pilot attempted to restart the engine, but was unsuccessful. At the same time, he turned the airplane towards a beach he had selected for an emergency landing. While still airborne, the airplane struck trees approximately 300 yards prior to the beach, and came to rest approximately 25 feet above the ground, suspended in the trees.

The co-owner/passenger provided a similar description of the sequence of events. He stated that the pilot performed the preflight inspection using a checklist, and stated that there were "31 to 32" gallons of fuel onboard at the beginning of the flight. The co-owner/passenger observed that the oil pressure and cylinder head temperature readings were "normal" during the return flight from VNC. He stated that when the airplane was in cruise at an altitude of approximately 1,100 feet, the engine suddenly stopped producing power, but the propeller continued to windmill. Both he and the pilot stated that the fuel selector valve was set to the "BOTH" position for the flight, as well as when the engine stopped developing power. He confirmed that the pilot turned the airplane towards a beach, and that they struck trees prior to reaching it. Both the pilot and the co-owner/passenger were wearing their seat belts and shoulder harnesses. They exited the airplane with the assistance of local fire and rescue personnel.

PERSONNEL INFORMATION

Federal Aviation Administration (FAA) records indicated that the pilot held a commercial pilot certificate with airplane single-engine land and instrument airplane ratings. He also held a ground instructor certificate with an advanced ground instructor rating. His most recent FAA second-class medical certificate was issued in May 2008, at which time he reported 404 total hours of flight experience. His most recent flight review was accomplished in September 2008. According to the pilot, at the time of the accident, he had 418 total hours of flight experience, including approximately 180 hours in the accident airplane make and model.

FAA records indicated that the co-owner/passenger held flight instructor and commercial pilot certificates, with airplane single-engine land, instrument airplane, and glider ratings. He also held a mechanic certificate with airframe and powerplant ratings, and an inspection authorization. His most recent FAA third-class medical certificate was issued in August 2006, at which time he reported 3,500 total hours of flight experience.

AIRPLANE INFORMATION

According to FAA records, the airplane was manufactured in 1973, and was first registered to the current owners in 2001. The airplane was equipped with a Lycoming O-320-E2D engine. According to the co-owner/passenger, the engine was last overhauled in September 1990, when it had a total time of approximately 2,000 hours in service. The airplane maintenance records indicated that the most recent annual inspection was completed on July 1, 2008, and a "Total A/C Time" of 3,198.5 hours was indicated in the entry. That entry was signed by the other co-owner of the airplane. Another maintenance records entry dated July 7, 2007, and which appeared to record an annual inspection, also cited a "Total A/C Time" of 3,198.5 hours. That entry was signed by the co-owner/passenger of the airplane.

The airplane tachometer registered 3,171.1 hours at the time of the accident. No other hour meter was installed on the airplane. The reason for the discrepancy between the maintenance records entries and the tachometer reading could not be determined.

METEOROLOGICAL INFORMATION

The 1053 automated weather observation at SRQ, located 6 miles north of the accident site, included winds from 270 degrees at 11 knots, visibility 10 miles, few clouds at 1,500 feet, temperature 28 degrees C, dew point 22 degrees C, and an altimeter setting of 29.94 inches of mercury.

The temperature and dew point values indicated a relative humidity of approximately 70 percent. When the intersection of the two temperature values was located on a chart that depicted carburetor ice envelopes, the point was in the envelope entitled "Serious Icing at Glide Power," near the boundary of the envelope entitled "Icing - Glide and Cruise Power."

WRECKAGE AND IMPACT INFORMATION

According to information provided by local law enforcement and FAA personnel who responded to the accident, the accident site was located approximately 6 miles south of the destination airport. The airplane came to rest slightly nose-down, with a bank attitude of approximately 60 degrees left wing down. The lower and aft fuselage sustained some crushing and tearing damage, but the cockpit/cabin area was predominantly intact. The flaps were found to be deployed to approximately 30 degrees. The empennage sustained significant crush and other deformation damage. Shortly after the accident, fuel was observed to be leaking from the tank vent tube in the left wing, but the fuel was not captured, and no estimates of the quantity were obtained. The airplane was recovered from the tree, and transported to a secure storage facility for additional examination.

According to a representative of the insurance company that insured the airplane, an environmental services company, in conjunction with Sarasota County environmental officials, conducted a limited site evaluation on June 11, which was 13 days after the accident. Soil samples were collected from several locations at the accident site. Samples were screened using a direct-reading instrument, and results of the soil screening found "no evidence of petroleum hydrocarbon impacts at the site."

ADDITIONAL INFORMATION

Airplane Fuel Quantity Information

FAA Type Certificate Data Sheet (TCDS) 3A12 stated that the accident airplane was equipped with two 21-gallon fuel tanks, for a total fuel capacity of 42 gallons. The TCDS stated that the usable fuel quantity was 38 gallons for "all flight attitudes" when the fuel selector valve was set to the "BOTH" position, and 19 gallons "in level flight" in either tank, when the fuel selector valve was set to that tank. According to the airplane manufacturer's Owner's Manual (OM), the airplane was equipped with two 21 gallon fuel tanks, one in each wing. A decal near each tank filler neck stated "19 GAL CAPACITY."

The OM performance charts indicated that gross weight fuel consumption values at an altitude of 2,500 feet ranged between 6.3 gallons per hour (gph) and 9.7 gph, depending on the engine power setting. Review of the performance charts indicated that approximately 1.5 gallons would be used for start and climb to 2,500 feet.

The exact amount of fuel on board at the start or end of the flight was not determined. No fuel receipts were provided for the investigation. Conversion of the pilot's estimates of "one-half tank" and "three-quarters tank" values to gallon values yielded a starting fuel quantity of approximately 26 gallons, which was 5 or 6 gallons less than the starting quantity estimated by the co-owner/passenger.

Airplane Examination

On June 3, which was 4 days after the accident, an FAA inspector and a representative of Cessna Aircraft examined the airplane at the storage facility. Approximately 1 gallon of blue colored fuel (similar to 100LL) was found in the left wing, and no fuel was found in the right wing. No water was detected in the fuel removed from the left tank. The fuel selector was found in the "Off" position. Control cable continuity for all primary flight controls was confirmed from the respective flight control bellcranks to the forward cockpit area; all cables had been cut during the wreckage extraction and recovery process. The elevator trim cables were disturbed or removed during the recovery, which precluded a determination of the pre-accident elevator trim position. The front seats remained attached and locked in place on their respective seat rails.

The engine remained attached to the fuselage, and the propeller remained attached to the engine. One propeller blade was bent aft approximately 10 degrees at the 1/3 span point, and exhibited some spanwise scratches. The other blade was straight, with some diagonal scratches. Longitudinal scratches were present on the spinner. The top four spark plugs were removed, and all exhibited coloration and wear consistent with normal operation. Thumb compression was detected at each cylinder when the crankshaft was rotated by hand, and both magnetos produced sparks at all leads.

An engine test run was performed at the recovery facility. Since the wings were removed for transport, a portable fuel tank was secured to the top of the fuselage. A line was routed from the tank to an airframe fuel line on the inlet side of the fuel selector valve, which permitted fuel to be provided to the fuel selector valve via gravity. The fuel strainer (gascolator) and the engine-driven fuel pump were intact and remained in the fuel system for the test run. The engine started quickly, and maintained approximately 2,000 rpm, with no anomalies. The fuel selector valve, gascolator, and engine-driven pump were all observed to be functional. The carburetor was removed and retained by the FAA for further analysis.

Carburetor History and Examination

A maintenance records entry dated November 18, 2008 stated "Installed rebuild [sic] carburetor model # MA-4SPA S/N BL209805 All paper in back of logbook." The entry did not include any tachometer or time-in-service information, and was signed by the co-owner/passenger. According to the co-owner/passenger, the airplane had not been operated between the annual inspection and the carburetor installation, and therefore the airplane time in service at the time of the carburetor installation was 3,198.5 hours. Documentation provided by the overhaul facility indicated that the carburetor that was installed in the accident airplane in November 2008 was overhauled in July 2007, using a "core" supplied by the co-owner.

The co-owner stated that after the rebuilt carburetor was first installed in November 2008, the engine did not run correctly, so he removed the carburetor and returned it to the overhaul facility to be repaired. The co-owner's letter to the overhaul facility stated that when the rebuilt carburetor was initially received, the "idle screw was turned all the way in," and that he spent "several days" adjusting the idle screw setting in order to get the engine to run properly. The letter stated that after that adjustment and a 20-minute flight, the engine could not be restarted until it cooled down. Finally, the letter stated that on the return flight, the engine "quit" on final approach, and the airplane was landed safely, but had to be towed off the runway, since the engine again could not be re-started.

Documentation provided by the overhaul facility indicated that the returned carburetor exhibited "immediate flooding on [the test] bench" because the float was "out of adjustment." The corrective actions accomplished by the overhaul facility included replacement of the float, needle valve and seat, "reset" of the float, and "precautionary" replacement of the acceleration pump seal. The repair facility conducted a functional check of the unit, which was documented in a "Carburetor Test Report." The repaired unit, with a "serviceable" tag bearing a date of "12/23/08," was returned to the co-owner, and reinstalled on the airplane. According to the co-owner, the engine then ran "fine" during a test flight. The airplane was not flown between the test flight and the accident flight.

Another maintenance records entry, which appeared just below the November 2008 carburetor entry, was dated April 3, 2009, and stated "Installed rebuild [sic] carburetor model # MA-4SPA S/S BL209805 overhauled by Avstar Aircraft Acc. Yellow tag in back of book." The entry did not include any airplane tachometer readings or time-in-service information, and was signed by the co-owner/passenger.

On July 16, 2009, the carburetor was examined at Avstar, the carburetor vendor/overhaul facility, with representatives from the FAA and Lycoming in attendance. The FAA inspector who witnessed the examination reported the following specifics. The overall condition of the unit was "good." The lock tabs on the screws that fastened the body segments together were properly adjusted, and no evidence of loose screws was observed. Application of 10 pound per square inch (psi) static pressure air to the fuel chamber and passages did not result in any leaks. The fuel inlet screen was clear of debris. The acceleration pump functioned normally. The acceleration pump inlet screen was clear of debris, and all parts were in "excellent condition."

The carburetor was equipped with metal floats that were manufactured by the vendor, and which were identified as appropriate for the carburetor. The preset float height adjustment was measured to be 13/64 inches, which was normal and within the allowable tolerance. The lateral float-to-body clearances appeared "sufficient." The float and needle valve components were removed; all were observed to be new and appropriate for the unit. A float leak check indicated that the float did not leak.

The fuel mixture adjustment screw was found to be backed out two turns from the fully-in position. This was one-half turn less than the as-delivered setting, which indicated that mixture was set slightly leaner than the as-delivered setting. A representative from the vendor stated that all MA-4 carburetors are delivered with the mixture adjustment screw at a standard setting, and that final adjustment setting is the responsibility of the technician who installs the carburetor, since that setting varies by airframe and engine.

No evidence of any component failures or malfunctions was identified during the examination and testing of the carburetor.

NTSB Probable Cause

A loss of engine power for undetermined reasons.