NTSB Factual Report

HISTORY OF FLIGHT

On July 22, 2000, about 1435 central daylight time, a Piper PA-23, N1069P, piloted by a private pilot, was destroyed during impact with terrain and post accident fire following a maneuver south of Dodge Center Airport, near Dodge Center, Minnesota. The flight was operating under 14 CFR Part 91. Visual meteorological conditions prevailed during the flight. No flight plan was on file. The pilot was fatally injured. The local flight originated from Dodge Center Airport at time unknown.

The annual inspection was completed on July 21, 2000. A fuel pump log indicates that on July 22, 2000, the airplane was fueled at 1426 with 88.89 gallons and at 1429 with 5.66 gallons. (See appended fuel pump log and pump legend.)

A witness stated that she was at the corner of County Road 10 and County Road I when she saw the airplane flying southbound along County Road I with its gear retracted. She said that the airplane was just above power lines, that the airplane made a turn to the east, and that the airplane was even lower when it made a turn back to the north. She stated that the airplane impacted the ground with its left wing and then impacted the ground with its nose. She said that the airplane spun around and burst into flames when it hit the ground. She stated that the engine was sputtering. At 1440, Dodge County Dispatch received her call reporting the airplane crash.

Another witness at the same corner stated that the engine was not loud and that it was sputtering. He estimated the power lines to be 35 feet above the ground and said that the airplane banked into a left turn, which was approximately 45 degrees of bank. He stated that the airplane descended during the left turn and impacted the ground with its left wing.

PERSONNEL INFORMATION

The pilot held a Private pilot certificate with Airplane Multiengine Land, Airplane Single Engine Land, and Instrument ratings. He held a 3rd Class Medical Certificate with no limitations, dated April 3, 2000. He listed 1,650 hours of flight time at the time of that medical examination.

AIRCRAFT INFORMATION

The airplane was a Piper PA-23, serial number 23-80. The airplane's annual inspection was completed on July 21, 2000. That inspection entry listed 4,285.6 hours total time on the airplane. Receipts indicate that both of the airplane's propellers were sent to a propeller repair station for "A/D COMPLIANCE".

METEOROLOGICAL INFORMATION

At 1454, the Rochester Municipal Airport, 139 degrees and about 17 nautical miles from Dodge Center Airport, observation was: Wind variable at 3 knots; visibility 10 statute miles; sky condition few 9,000 feet; temperature 23 degrees C; dew point 13 degrees C; altimeter 30.18 inches of mercury.

WRECKAGE AND IMPACT INFORMATION

The airplane's nose came to rest in a bean field about 515 feet south of County Road 10 and about 718 feet east of County Road I. An area approximately 4 feet wide and between 30 to 100 feet west of the airplane's nose was found devoid of vegetation. In this area, a piece of translucent red colored media and a navigation light assembly were found approximately 88 feet west of the airplane's nose. An indentation in the ground within this area, approximately 2 feet in diameter and one foot below grade, was found approximately 54 feet west of the airplane's nose. Another indentation within this area, approximately 1 foot in diameter and one foot below grade, was found approximately 37 feet west of the airplane's nose. The left wing outboard of the spar splice was found detached, deformed, discolored, and covered with a soot like substance. The inboard portion of the left wing was found detached from the airframe at its root and the left flap was found loosely attached and resting under the wing. The right wing was found attached to the fuselage. The right wing, outboard of the nacelle, was found deformed, discolored, and covered with a soot like substance. All landing gear were found in the retracted position.

An on-scene investigation was conducted. The airplane exhibited continuity to all control surfaces. Continuity was found to both engines. A thumb compression was found at all cylinders. The right engine's left magneto revealed melted internal parts and did not produce a spark when rotated. All other magnetos produced a spark when rotated. A liquid was found in the left engine's carburetor bowl. That liquid was observed and it revealed it consisted of fluids that did not mix together. The left wing had 38.4 gallons of a blue colored liquid extracted from its inboard 36-gallon tank. Both carburetor inlet screens were removed and observed. Both of these screens contained a media. (See appended photographs.)

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy was performed on the pilot by the Ramsey County Medical Examiner on July 24, 2000.

The FAA Civil Aeromedical Institute prepared a Final Forensic Toxicology Accident Report. The report was negative.

FIRE

A witness said that the airplane burst into flames when it hit the ground. Approximately a 40-foot oval shaped area, centered about where the airplane's nose came to rest, was found devoid of vegetation. Charred remnants of vegetation within and vegetation along the edge of this oval was found discolored, charred, and covered with a soot like substance.

TESTS AND RESEARCH

The liquid found in the carburetor was sent to the DuPage County Sheriff's Office Crime Laboratory, Wheaton, Illinois, for examination. The report stated, "Instrumental analysis of item 1 revealed the presence of water and a flammable liquid consistent with aviation fluid. Microscopical examination of item 1 revealed the presence of the following: mineral matter; plant matter; fibers; glass like particles; metallic particles; unidentified particles."

The fuel screen assemblies and the media they contained were sent to the National Transportation Safety Board's Materials Laboratory for examination. The portion of the report on the right screen stated, "Examination of the cylindrical screen revealed the sides were partially blocked with debris and the round end was totally blocked. Approximately 60% of the screen mesh was blocked with debris. ... The majority of the debris consisted of black flakes of various sizes, mostly with a slight curvature. ... A small number of tan colored flakes and an even smaller number of red colored flakes were also observed. ... The flakes were analyzed using X-ray energy dispersive spectroscopy (EDS). Spectra from all the flakes were similar and displayed peaks of barium, lead and silicon with traces of copper, iron, zinc, aluminum, carbon and oxygen." A piece of debris was found "that appeared to have a fibrous appearance similar to wood." The portion of the report on the left screen stated, "Examination of the cylindrical screen revealed that the sides were partially blocked with debris, although not as badly as screen 'R' and the round end was totally blocked. Approximately 30% of the screen mesh was blocked. ... The majority of the debris consisted of black flakes of various sizes, mostly with a slight curvature, similar in appearance to those illustrated in figure 3 although fewer and generally smaller. ... The spectra from EDS analysis of the flakes in [the left screen] was very similar to the spectra of the flakes found in [the right screen]." A piece of debris was found that acted "in an elastomeric manner." Particles, other than flakes were found. A particle was found to be "hard and shiny with an undulating surface." Another particle had "a fibrous appearance similar to wood." A brown colored particle with folds, "was thin and had a rubbery consistency." Shiny metal particles were found to be predominantly aluminum with a trace of iron. A particle was found that had the appearance of sandstone and displayed a spectra of "a large silicon peak, a small iron peak and traces of aluminum, calcium, lead and chlorine." (See appended Materials Laboratory Factual Report No. 01-041.)

Both propellers and propeller governors were shipped to Hartzell Propeller Inc. for examination. No anomalies were observed during the teardown. Both propellers had internal witness marks that showed the blades in low blade angle. The left governor was mounted on a test stand and was test run. No anomalies were found with the left governor. The right governor was not tested. (See appended Hartzell Propeller Teardown Report.)

ADDITIONAL INFORMATION

The Piper PA-23-160 Owners Handbook stated, "The fuel tanks should be kept full of fuel during storage of the airplane to prevent accumulation of moisture, and to prevent deterioration of the rubber cells." The handbook also stated, "The Apache is designed to take gear-up emergency landings without extensive damage to the structure of the airplane. All three wheels protrude about one-third of their diameter when retracted, and structure is provided to take minor loads in this condition."

The Federal Aviation Administration Advisory Circular 20-43C, Aircraft Fuel Control, stated the following concerning fuel contamination: " 9. WHAT IS FUEL CONTAMINATION? Fuel is contaminated when it contains any material that was not provided under the fuel specification. This material generally consists of water, rust, sand, dust, microbial growth, and certain additives that are not compatible with the fuel, fuel system materials and engines.

10. WHAT CAUSES FUEL CONTAMINATION?

a. Water. All aviation fuels absorb moisture from the air and contain water in both suspended particle and liquid form. The amount of suspended particles varies with the temperature of the fuel. Whenever the temperature of the fuel is decreased, some of the suspended particles are drawn out of the solution and slowly fall to the bottom of the tank. Whenever the temperature of the fuel increases, water is drawn from the atmosphere to maintain a saturated solution. Changes in fuel temperature, therefore, result in a continuous accumulation of water. During freezing temperatures, this water may turn to ice, restricting or stopping fuel flow.

b. Rust. Pipelines, storage tanks, fuel trucks, and drum containers tend to produce rust that can be carried in the fuel in small size particles. A high degree of filtration is required to remove the liquid water and rust particles from the fuel.

c. Dust and sand. The fuel may be contaminated with dust and sand through openings in tanks and from the use of fuel handling equipment that is not clean.

d. Micro-organisms. Many types of microbes have been found in unleaded fuels, particularly in the turbine engine fuels. The microbes, which may come from the atmosphere or storage tanks, live at the interface between the fuel and liquid water in the tank. These micro-organisms of bacteria and fungi rapidly multiply and cause serious corrosion in tanks and may clog filters, screens, and fuel metering equipment. The growth and corrosion are particularly serious in the presence of other forms of contamination.

e. Additives. Certain oil companies, in developing products to cope with aircraft fuel icing problems, found that their products also checked "bug" growth. These products, known as 'biocides,' are usually referred to as additives. Some additives may not be compatible with the fuel or the materials in the fuel system and may be harmful to other parts of the engine with which they come in contact. Additives that have not been approved by the manufacturer and FAA should not be used.

11. FIELD TESTS. Three gallons of water were added to the half full fuel tank of a popular make, high wing monoplane. After several minutes, the fuel strainer (gascolator) was checked for water. It was necessary to drain ten liquid ounces of fuel before any water appeared. This is considerably more than most pilots drain when checking for water.

In another test, simulating a tricycle geared model, one gallon of water was added to the half full fuel tank. It was necessary to drain more than a quart of fuel before any water appeared.

In both of these tests, about nine ounces of water remained in the fuel tank after the belly drain and the fuel strainer (gascolator) had ceased to show any trace of water. This residual water could only be removed by draining the tank sumps.

12. CONTAMINATION CONTROL. The presence of any contamination in fuel systems is dangerous. Laboratory and field tests have demonstrated that when water was introduced into the gasoline tank, it immediately settled to the bottom. Fuel tanks are constructed with sumps to trap this water. It is practically impossible to drain all water from the tanks through the fuel lines, so it becomes necessary to regularly drain the fuel sumps in order to remove all water from the system. It may be necessary to gently rock the wings of some aircraft while draining the sumps to completely drain all the water. On certain tailwheel type aircraft, raising the tail to level flight attitude may result in additional flow of water to the gascolator or main fuel strainer. If left undrained, the water accumulates and will pass through the fuel line to the engine and may cause the engine to stop operating. The elimination of contaminants from aviation fuel may not be entirely possible, but we can control it by the application of good housekeeping habits.

a. Servicing. Storage and dispensing equipment should be kept clean at all times - free from dirt and other foreign matter. Fuel having a 'cloudy' appearance or definitely 'offcolor' should be suspected of contamination or deterioration and should not be used. When additives are used, it is important that they are dispensed in accordance with the aircraft manufacturer's instructions.

Refueling from drums or cans should be considered as an unsatisfactory operation and one to be avoided whenever possible. All containers of this type are to be regarded with suspicion and the contents carefully inspected, identified, and checked for water and other contamination. Extraordinary precautions are necessary to eliminate the hazards of water and sediment. It is advisable when fueling from drums to use a 5 micron filtered portable pumping unit, or the best filtering equipment available locally, or, as a last resort, a chamois skin filter and filter funnel.

Infrequently used fuel tanks should have their sumps drained before filling. Agitation action of fuel entering the tank may suspend or entrain liquid water or other contaminants - which can remain suspended for many minutes and may not settle out until after the aircraft is airborne.

b. Preflight action. Drain a generous sample of fuel - considerably more than just a trickle - into a transparent container from each of the fuel sumps and from the main fuel strainer or gascolator. (Remember that it was necessary to drain ten ounces in the field tests.) On certain aircraft having fuel tanks located in each wing, positioning of the fuel tank selector valve to the 'BOTH ON' position may not adequately drain the system. This is due to the fuel taking the path of least resistance. In this case, the fuel selector valve should be positioned at each tank in turn.

Examine the fuel samples for water and dirt contamination. If present, it will collect at the bottom of the container and should be easily detected. Continue to drain fuel from the contaminated sump until certain the system is clear of all water and dirt.

'The use of quick drain valves in the sumps and gascolator makes it practical to keep tanks free of significant quantities of water and other contaminants.'

c. Postflight. An effective method to prevent contamination from condensation would be to completely fill the fuel tank at the end of each day's flying. This procedure is practical only on a few types of light aircraft. Generally, the type of aircraft, length of proposed flight, number of passengers, and weight and balance limitations dictate the amount of fuel to be added.

d. Routine maintenance. In addition to the preflight and postflight actions, certain precautionary or routine maintenance should be performed on the aircraft at periodic intervals. These precautions include the inspection and cleaning of pertinent fuel tank outlet finger strainers and carburetor

NTSB Probable Cause

The pilot not maintaining airplane control in his turn back in the direction of the airport and the pilot not performing an emergency landing straight ahead. Factors were the water and debris contamination found in the fuel screens and carburetor bowl and the stall the pilot encountered during his turn in the direction of the airport.