DEN03FA074

Several witnesses observed the airplane prior to the accident. One witness said the airplane had been doing aerobatics in the area - "loops and figure eights" The witness said as the airplane proceeded eastward, it got lower in altitude. The witness said, "He was about 500 feet over the field, he did a low loop and came back up the backside of the loop in what appeared to be an attempt at a hammerhead stall. The engine sputtered and quit and there wasn't room for a recovery." Another witness said he was driving north and saw the airplane overhead. He said the airplane had just done a loop and was going up vertically. The witness said he lost sight of the airplane. When he saw the airplane again, it was coming down at nearly an 80-degree angle until it impacted into the field. A third witness said he heard the sound of the airplane's engine change suddenly. He said he looked up to see the airplane low to the ground and heading straight down. He said, "The engine sound was as if the engine had quit." A fourth witness said the airplane made several loud pops as it was heading towards the ground. An examination of the airplane's engine showed no fuel in the fuel distribution manifold, distribution lines, nozzles, fuel filter, or in the fuel lines from the main fuel tank to the engine fuel pumps. Approximately 0.10 ounces of fuel was retrieved from the engine driven fuel pump. The fuel boost pump was broken aft and showed no evidence of fuel. All other engine components examined and tested revealed no pre-impact anomalies. No other anomalies were found with the airplane.

History of flight

On April 26, 2003, at 1215 mountain daylight time, a Christen Industries, Pitts S-2B, N399DB, piloted by a private pilot, was destroyed when it impacted into a field 3 miles north of Longmont, Colorado. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under the provisions of Title 14 CFR Part 91 without a flight plan. The pilot and a commercial pilot-rated passenger on board the airplane were fatally injured. The local flight originated at Boulder, Colorado, at 1000.

Several witnesses observed the airplane prior to the accident. One witness said the airplane had been doing aerobatics in the area - "loops and figure eights" The witness said as the airplane proceeded eastward, it got lower in altitude. The witness said, "He was about 500 feet over the field, he did a low loop and came back up the backside of the loop in what appeared to be an attempt at a hammerhead stall. The engine sputtered and quit and there wasn't room for a recovery."

Another witness said he was driving north and saw the airplane overhead. He said the airplane had just done a loop and was going up vertically. The witness said he lost sight of the airplane. When he saw the airplane again, it was coming down at nearly an 80-degree angle until it impacted into the field.

A third witness said he heard the sound of the airplane's engine change suddenly. He said he looked up to see the airplane low to the ground and heading straight down. He said, "The engine sound was as if the engine had quit."

A fourth witness said the airplane made several loud pops as it was heading towards the ground.

Personnel information

The pilot-in-command (rear cockpit seat) held a private pilot certificate dated 05/24/2000, with single engine land, instrument ratings, and glider ratings.

According to his personal logbook, the pilot had 2,408.0 total flying hours and 105.2 total hours in the make and model airplane.

The pilot held a third class medical certificate dated 09/21/2001. The certificate showed the following limitation: Holder shall possess correcting glasses for near vision while exercising the privileges of his/her airman certificate.

The pilot-rated passenger in the front seat held a commercial pilot certificate dated 10/22/1999, with single and multiengine land, instrument, and helicopter/rotorcraft ratings.

Federal Aviation Administration aeromedical records showed the pilot reporting having approximately 3,000 total flying hours.

The pilot-rated passenger held a second class medical certificate dated 02/05/2003. The certificate showed no limitations.

Aircraft information

The airplane, a Christen Industries Pitts S-2B, serial number 5137, was a bi-winged, fabric-covered, canopy enclosed cockpit airplane, certified for aerobatic flight. The airplane, manufactured in 1988, was owned and operated by Connair, Incorporated, and used for pleasure. The airplane's most recent registration was dated January 7, 2002.

According to the airplane logbooks, the airplane had an annual inspection completed on November 11, 2002. The airplane's total time at the annual inspection, taken from the tachometer, was recorded as 216.20 hours. The airplane's tachometer reading at the accident site showed 261.05 hours.

Wreckage and impact information

The National Transportation Safety Board on-scene investigation began at 1450.

The accident site was located in a field approximately 100 feet east of 83rd Avenue, a north-south running paved road, 1,060 feet south of Yellowstone Road, an east-west running gravel road, and 3 miles north of Colorado State Highway 66 at Longmont, Colorado, an east-west running, paved 4-lane road. The accident site was located at geographical coordinates 40 degrees 14.77 minutes north latitude, and 105 degrees 09.68 minutes west longitude.

The airplane main wreckage consisted of the engine, propeller, fuselage, main landing gear, wings, empennage, and tail wheel. The wreckage was oriented on a 255-degree magnetic heading.

The airplane's engine, propeller, cowling, and forward fuselage, rested in a 3-foot long, 4-foot wide, and 17-inch deep impact crater. The three wood propeller blades were broken aft. Blade A was broken aft at the hub and showed some leading edge crush at mid-span. Blade B was broken at the hub and was crushed and broken aft. Blade B showed some nicks in the leading edge metal strip. Blade C was broken aft approximately 3 inches outboard of the hub. The fractured blade was highly fragmented and splintered. Blade C also showed chordwise scratches near the blade tip and some nicks in the leading edge metal strip. The propeller spinner was crushed aft and fragmented. The aft spinner plate showed a 5 inch long scrape in the plane of rotation. All three propeller blades were in the low pitch position.

The ring cowling, bottom cowling, and bottom forward fuselage were crushed upward and aft. The side and upper cowlings were bent aft and broken open. The airplane's firewall and forward main fuel tank were crushed forward against the engine's accessories section. Three puncture holes, approximately 3-inches in diameter, were observed in the top front of the firewall through into the forward main fuel tank. The main landing gear legs were bent aft. The front of the left and right wheel pants were crushed. The main gear tires and brakes were intact.

The airplane's canopy was broken aft and away from the fuselage. The canopy frame was located 12 feet east-northeast of the main wreckage. The Plexiglas was broken out and fragmented. The canopy frame was bent and twisted.

The front cockpit right side wall and fuselage frame tubing in that area were bent downward and crushed aft. The left wall was broken open and outward, and crushed aft. The front cockpit floor and pilot seat pan were bent upward. The front cockpit instrument panel was bent forward and crushed downward. Most of the flight instruments in the forward instrument panel were broken out and destroyed.

The surviving engine instrument from the front cockpit instrument panel showed the following indication:

Tachometer: 1,950 revolutions per minute

The rear cockpit walls and floor showed skin wrinkling. The rear pilot seat was intact. The shoulder harness was broken at the frame attach point. The rear cockpit instrument panel was bent forward in the middle. Most of the flight and engine instruments were intact. The bulkhead separating the front and rear cockpits was bent forward into the front pilot seat.

Flight instruments from rear cockpit instrument panel showed the following indications:

Airspeed indicator: 95 miles per hour

Altimeter: 5,345 feet

Kollsman window: 29.97 inches of Mercury (Hg)

Accelerometer: destroyed

Engine instruments from the rear cockpit instrument panel showed the following indications:

Tachometer: 2,450 revolutions per minute

Hobbs meter: 261.05 hours

Manifold pressure: 26 inches Hg

Oil pressure: destroyed

Oil temperature: destroyed

Exhaust gas temperature indicator: destroyed

Ammeter: broken, needle read zero

Engine controls at the rear cockpit were observed at the following positions:

Throttle: full open

Mixture: full rich

Starter switch: both

Cowl flaps: intermediate position between open and closed

Carburetor Heat: intermediate position between open and full cold

Fuel Selector: Main tank selected

Auxiliary fuel tank selector: Off

The top wing was broken forward at the over-fuselage and outboard wing struts. The top wing was also broken longitudinally into two pieces at the center, exposing the wing fuel tank. The fuel tank was intact and showed no evidence of fuel. The leading edge of the wing was crushed aft approximately 8 inches along its entire span. The fabric wing skin was torn longitudinally near the wing tips. Several of