DEN03FA025

The pilot reported to Denver Air Route Traffic Control Center (ZDV) that his left engine had an oil leak and he requested to land at the nearest airport. ZDV informed the pilot that Akron (AKO) was the closest airport and subsequently cleared the pilot to AKO. On reporting having the airport in sight ZDV terminated radar service, told the pilot to change to the advisory frequency, and reminded him to close his flight plan. Approximately 17 minutes later, ZDV contacted Denver FSS to inquire if the airplane had landed at AKO. Flight Service had not heard from the pilot, and began a search. Approximately 13 minutes later, the local sheriff found the airplane off of the airport. Witnesses on the ground reported seeing the airplane flying westbound. They then saw the airplane suddenly pitch nose down, "spiral two times, and crash." The airplane exploded on impact and was consumed by fire. An examination of the airplane's left engine showed the number 2 and 3 rods were fractured at the journals. The number 2 and 3 pistons were heavily spalded. The engine case halves were fretted at the seam and through bolts. All 6 cylinders showed fretting between the bases and the case at the connecting bolts. The outside of the engine case showed heat and oil discoloration. The airplane's right engine showed similar fretting at the case halves and cylinder bases, and evidence of oil seepage around the seals. It also showed heat and oil discoloration. An examination of the propellers showed that both propellers were at or near low pitch at the time of the accident. The examination also showed evidence the right propeller was being operated under power at impact, and the left propeller was operating under conditions of low or no power at impact. According to the propeller manufacturer, in a sudden engine seizure event, the propeller is below the propeller lock latch rpm. In this situation, the propeller cannot be feathered. Repair station records showed the airplane had been brought in several times for left engine oil leaks. One record showed a 3/4 inch crack found at one of the case half bolts beneath the induction manifold, was repaired by retorquing the case halves and sealing the seam with an unapproved resin. Records also showed the station washed the engine and cowling as the repair action for another oil leak.

History of flight

On December 25, 2002, at 1006 mountain standard time, a Cessna 421, N421D, piloted by a private pilot, was destroyed when it impacted terrain 1/8 mile west of the Akron/Washington County Airport (AKO), Akron, Colorado. A post crash fire ensued. Visual meteorological conditions prevailed at the time of the accident. The personal cross-country flight was operating on an instrument flight rules flight plan from Englewood, Colorado, to Mitchell, South Dakota, under the provisions of Title 14 CFR Part 91. The pilot and passenger on board sustained fatal injuries. The flight originated at 0933.

At 0959, the pilot reported to the Denver Air Route Traffic Control Center (ZDV) that his left engine had an oil leak and requested to land at the nearest airport. ZDV informed the pilot that AKO was the closest airport and subsequently cleared the pilot direct to AKO.

At 1001, the pilot reported having the airport in sight. ZDV radar showed the airplane in a 3,000 foot per minute descent passing through 17,000 feet mean sea level.

At 1003, ZDV terminated radar service, told the pilot to change to the advisory frequency, and reminded him to close his flight plan.

At approximately 1004, ZDV radar lost contact with the airplane. When contact was lost, the airplane was approximately 3.5 miles southwest of the Akron VOR and 5 miles south of the airport.

At 1016, ZDV contacted Denver Flight Service to ensure the airplane had landed at AKO and the pilot had closed his flight plan. Flight Service said they had not heard from the pilot, but would look into it. At 1023, Flight Service contacted the Washington County, Colorado Sheriff and asked if they could send a car to AKO to see if the pilot was there. At 1029, Flight Service informed ZDV that the sheriff's department said "he ran off the runway and thundered it up a little bit ..."

A witness on the ground observed the airplane come from the north toward the airport. He said the airplane made a sharp right hand turn over a football field and flew west over the old runway. The witness said he saw a vapor trail coming from the right side tail. He said he could hear what sounded like one engine. The witness estimated the airplane was 1,000 feet above the ground.

Two witnesses driving eastbound toward the airport reported seeing the airplane flying westbound. The airplane was then observed to suddenly pitch nose down, "spiral two times, and crash."

Personnel information

The pilot held a private pilot certificate with single and multiengine land, and instrument ratings. The pilot's logbooks sustained fire damage in the accident. The information derived from the logbook indicated that the pilot had 1,230.2 total flying hours. The logbook showed the pilot had 1,068.8 hours as pilot-in-command and 252.7 hours in multiengine land airplanes. The logbook also showed the pilot having 21.6 hours in the accident airplane. This time was logged between June 24, 2002, and November 19, 2002. The logbook also showed the pilot completed a flight review and instrument competency check on June 21, 2002.

Aircraft insurance records indicate the pilot completed an initial flight training course for the Cessna 421 at Champaign, Illinois, on June 21, 2002. The training course consisted of 8.0 hours of classroom instruction and 9.5 hours of simulator flight training.

Aircraft information

The airplane was manufactured in 1967, was owned and operated by the pilot, and used for pleasure. The airplane's current registration was dated June 4, 2002. According to repair station records, an annual inspection was performed in Tulsa, Oklahoma, on April 10, 2002. A pre-purchase evaluation was done on the airplane on May 6, 2002. At the time of that evaluation, the total airframe time was 3,532 hours. The airplane's Hobbs meter and tachometer were destroyed by impact and fire in the accident; however, pilot records indicate the airplane was flown at least an additional 21.6 hours.

Wreckage and impact information

The National Transportation Safety Board on-scene investigation began at 1550.

The accident site was located in a pasture approximately 150 feet west of Washington County Road AA5, a north-south running gravel road, and at geographical coordinates 40 degrees 11.001 minutes north latitude, and 103 degrees 14.315 minutes west longitude.

An area of burned grassland encompassed the accident site. The accident site covered an area approximately 205 feet north to south and 163 feet east to west. The accident site began with two impact craters located at the site's north edge, running along an east-west line. The western-most crater was 2 feet long, 4 feet wide and 18 inches deep. The airplane's left propeller hub, spinner cone, and two blades rested upright in the crater. The left propeller was oriented on a 360-degree magnetic heading. The second crater was 14 feet east of the west crater. It was approximately 3 feet long, 20 inches wide, and 20 inches deep. The airplane's right propeller and spinner were embedded in the crater at a 54-degree down angle from horizontal. Both propellers were broken off at the flanges.

The left propeller hub was broken where the third of a 3-bladed propeller was seated. The third propeller blade rested just south of the left propeller and west crater. The spinner cone was crushed aft around the propeller cylinder and hub. The two blades with the hub were at the low pitch position and showed charred and slight aft bending. There were chordwise scratches on the front-facing sides of the two blades near the blade tips, beginning at the blades' leading edges. The third blade was bent rearward and charred.

The right propeller's spinner cone was crushed aft around the hub cylinder and hub. The propeller hub was broken. The three propeller blades were at the low pitch position. All three blades showed torsional bending, chordwise scratches, and leading and trailing edge nicks and gouges.

In the area between the two propellers, running northward of the east-west line the propellers lay along, were numerous pieces of clear Plexiglas. The pieces ran northward of the east-west line for approximately 21 feet. The pieces were fragmented, charred and melted. The airplane's VHF antennae rested upside down on the ground 12 feet north of the left propeller. It was broken off at the base. Approximately 35 feet north-northeast of the left propeller rested a piece of the left wing tank and fuel cap.

Approximately 3 feet to the right of the east crater and right propeller was a 3-foot by 3-foot piece of the front cabin wall. At 8 feet east-southeast of the right propeller were a nose baggage door and the front portion of the right wing tip fuel tank. The baggage door was broken out at the hinges and latches. The latches were flush with the door and the latch bayonets were extended. The inner side of the door was charred and melted. The right wing tip fuel tank was crushed aft and broken open. The tank portion was also charred and melted.

Approximately 14 feet west of the west crater and left propeller was the front portion of the left wing tip fuel tank. It was crushed aft, broken open, charred and melted.

In an area beginning at the east-west line described by the two craters and the left and right propellers, and running south for approximately 28 feet was a debris field. The debris field contained pieces of fragmented instrument panel, flight instruments, a main landing gear door, pieces of wing skin, cowling doors, and engine components.

At 28 feet south of the propellers and impact craters were the remains of the airplane's nose section, instrument panel, cabin, wings, right engine and nacelle, and main and nose landing gear. The airplane's wings and fuselage were oriented on a 180-degree magnetic heading. The nose section of the airplane, to include the baggage compartment