NTSB Factual Report

HISTORY OF FLIGHT

On October 25, 1994, at 1906 mountain daylight time, a Piper PA- 28-235, N8954W, was destroyed by ground impact and postimpact fire near Aurora Airpark, Aurora, Colorado. Both pilots sustained fatal injuries. Visual meteorological conditions prevailed for this local area instructional flight and no flight plan was filed. The flight originated about 1800.

Persons at the airpark stated that they received a request for an airport advisory from the aircraft about 1900 on the UNICOM frequency. About 1910, the airport manager saw a fire burning southeast of the field and went to investigate. He found the aircraft in flames with both occupants still on board. Emergency crews arrived about 5 minutes later. They were notified by another person who saw the fire and called 911.

The accident site is located approximately 900 feet off the southeast end of runway 14 at Aurora Airpark. Runway 14 was the preferred runway in use at the time of the accident.

According to personnel at the airpark, the owner of the aircraft was receiving a night check out. The flight had been airborne about an hour and had returned to the pattern when the accident occurred.

The terrain off the end of the runway where the accident occurred consists of farm fields. There is a farm house with a yard light approximately a mile off the end of the runway, and a second farm house with a yard light about one half mile to the east of the runway end. Those are the only lights off the end of the runway where the accident occurred.

PERSONNEL INFORMATION

According to persons who knew the flight instructor, he had flown out of Aurora Airpark for some time and was familiar with the area. Available information indicates that he had not flown at night in the recent past.

Records provided by the airpark indicate the owner of the aircraft, who was receiving instruction, had flown for six tenths of an hour on October 1, 1994, and one hour on October 21, 1994. No other records of recent flight time were found. FAA records provided information that this pilot had 145 hours total flight time and his certificate was issued on March 15, 1994.

METEOROLOGICAL INFORMATION

According to the National Weather Service, weather at the time of the accident was clear skies with 40 miles of visibility. Persons at the airpark stated that it was dark and there was no moon. Observation by this investigator, the night following the accident, provided information that on a clear, dark, moonless night there was no visible horizon to the south and southeast off the end of runway 14.

AERODROME INFORMATION

Aurora Airpark is a private airport open to the public and is located 11 miles east of the city of Aurora. It is bordered on the north by an interstate highway and on the other three sides by open farm land. Lighting consists of threshold and runway lights which are pilot controlled. The airport is VFR only.

WRECKAGE AND IMPACT INFORMATION

The first ground scar found consisted of a shallow gouge which contained the pitot tube. From that witness mark, the ground scar track was on a base heading of 74 degrees. Fifteen feet from the first mark was a deep gouge which contained some engine oil residue.

Twenty two feet to the southeast from the deep gouge the left wing was found. The wing was fire damaged and the tip tank was missing.

The fuselage, oriented towards the northeast, was located 37 feet beyond the deep gouge. The engine was attached and the forward half of the fuselage and engine were fire damaged.

The right wing remained attached to the fuselage by cables and was oriented to the north. The aileron was attached and flight control continuity through the wing was established. The tip tank was attached. The left tip tank was found 31 feet to the northwest of the fuselage. The tip tank was damaged. (Refer to wreckage diagram.)

Fuel was not found in the left wing. However, the wing had burned and evidence of a fuel fire was present along with a fuel odor in the vicinity of the wing. The right wing tank was about one half full and the fuel selector in the fuselage was positioned on the right main tank. Neither tip tank contained fuel or evidence that they had contained fuel at the time of the accident.

The engine sustained some fire damage around the bottom of cylinders 2 and 4. In addition, the following damage was observed.

Number 2 intake pipe was pushed back. Number 2 exhaust pipe was flattened into number 4 intake pipe. Number 4 exhaust pipe was pushed back into number 6 intake pipe. The alternator was displaced rearward. The carburetor was broken off just below the mounting flange. Three ignition leads were smashed at the right magneto cap. The top of the mounting flange of the left magneto was broken. Five of the ignition leads from the left magneto were smashed at the cap. The airbox was smashed up against the bottom of the carburetor.

The above noted damage was associated with impact forces and fire.

The propeller remained attached and both blades were bent rearward. One blade exhibited chordwise scratches.

The empennage was intact and sustained minor damage. All flight control surfaces were properly attached and flight control continuity was established.

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy and toxicological examination was conducted on both victims by the Arapahoe County Medical Examiner. No abnormalities were noted and death was attributed to blunt force trauma associated with impact forces.

TESTS AND RESEARCH

An engine examination was conducted at the facilities of Beegles Aircraft Services, Greeley, Colorado. That examination is detailed as follows:

Following removal of one spark plug from each cylinder, engine continuity was checked and found to be normal. The crankshaft was rotated and thumb compression was confirmed on cylinders 2,3,4, and 6. Compression on cylinder number 3 was noticeably lower than 2,4, and 6. There was no compression found on cylinders 1 and 5.

All cylinders were removed and examined. Number 5 cylinder exhibited some scuffing near the top of the barrel. Corresponding scuffing was noted near the top of the piston. The top compression ring was broken into six pieces. Rubbing damage to several of the fracture surfaces provided evidence that the engine had operated with the broken ring for some time. Visual examination of the ring revealed wear on the sides. The corresponding ring groove exhibited a similar wear pattern. The second compression ring was intact and free in the groove.

Number 1 cylinder had light scuffing near the top of the barrel and corresponding scuffing near the top of the piston. The top compression ring was broken near the gap. The broken section measured approximately .375 inches in length. The second compression ring and the oil ring were both intact and free in the piston ring grooves.

The other cylinders had varying degrees of scuffing in the barrels and on the pistons. The piston rings were intact and free in the ring grooves. The valves and valve springs all appeared normal. No evidence was found to indicate why the compression in number 3 cylinder was low.

The accessory housing was removed and all accessory drive gears were intact. The crankshaft gear bolt, lockplate, and dowel were intact and showed no evidence of wear. The oil pump turned freely by hand. Disassembly of the pump revealed that the gears and shaft were intact and operable.

The right magneto was a Bendix S6LN-20 (red label), S/N 863093. Spark was produced at all lead towers when the shaft was rotated with an electric drill.

The left magneto was a Bendix S6LN-21 (blue label), S/N 450276. It produced spark at all lead towers when the shaft was turned with an electric drill. The impulse coupling functioned.

The carburetor was a Marvel Schebler MA-4-5, setting 10-4404, S/N R-6-3450. The data plate also had the letter V stamped on it indicating a single piece venturi. The fuel inlet screen was removed and found clean. Removal of the float bowl revealed a composite float which was heat damaged. The float, needle valve and clip were properly installed. The float and needle valve moved freely. The viton tip was melted off the needle valve. The accelerator pump linkage was intact and moved freely. The seal on the accelerator pump piston was destroyed by heat. The inside of the float bowl was clean. The throttle valve was intact and the shaft moved freely. Heat damage precluded testing the float and needle valve.

The engine driven fuel pump was an AC diaphragm type. The housing was broken. It was disassembled and a smell of fuel was detected. Both valves and both diaphragms were intact. The actuating arm and spring were also intact.

According to the aircraft records, the engine had accumulated 2,253 hours total time and 1,070 hours since major overhaul, which occurred on February 15, 1977. Log entries provided information that the last annual inspection was performed on July 21, 1994. Time since the annual could not be determined.

The investigation did not reveal any preimpact mechanical discrepancy that would have prevented the engine from producing sufficient power to sustain flight. The broken rings and cold thumb compression loss would have caused an undiscernible maximum power decrease according to the FAA airworthiness inspector and Beegles aircraft mechanic who assisted in the examination. These persons said that the power loss would not have been noticeable to the pilot.

ADDITIONAL DATA/INFORMATION

The wreckage was released to Mr. Dennis Jason, Jason and Associates, on October 27, 1994. No parts were retained.

NTSB Probable Cause

THE CFI's FAILURE TO MAINTAIN AIRCRAFT CONTROL DUE TO SPATIAL DISORIENTATION. FACTORS WERE: A DARK, MOONLESS NIGHT WITH NO VISIBLE HORIZON AND RECENCY OF NIGHT EXPERIENCE BY THE FLIGHT INSTRUCTOR.