National Transportation Safety Board - Docket And Docket Items: http://dms.ntsb.gov/pubdms
National Transportation Safety Board - Aviation Accident Data Summary: http://app.ntsb.gov/pdf
NTSB Identification: CEN14FA072
14 CFR Part 91: General AviationAccident occurred Wednesday, November 27, 2013 in Boulder, CO
Probable Cause Approval Date: 02/08/2016
Aircraft: BIESEMEIER DAVID I SMYTH SIDEWINDER, registration: N3786A
Injuries: 1 Fatal.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
Radar data showed that, during the first 15 minutes of the cross-country flight, the experimental, amateur-built, airplane had a normal departure and climbout. However, the airplane then suddenly turned and rapidly descended. A witness reported that he heard a loud sound, looked up, and saw the airplane falling out of the sky. Another witness reported seeing flocks of migrating birds in the area about the time of the accident. No radio calls or distress transmissions were received from the pilot. The airplane’s left wing was found about 1,156 ft from the main wreckage. Examination of the engine and flight controls did not reveal any mechanical anomalies that might have contributed to the accident.
Examination of the left wing revealed no evidence of preexisting conditions that would have contributed to its separation. The wing’s left lower spar cap was fractured about 8 inches outboard of the attachment point through the two rivet holes immediately outboard of the wing-to-fuselage fittings. There was no obvious deformation of the lower spar cap members in the fracture area. The upper spar cap members were fractured between 10 and 12 inches outboard of the attachment point with significant S-type bending of the members in the fracture area. The upper shear bolt remained intact and installed, but the lug portion of the fuselage fitting was fractured. The fracture faces on the upper and lower spar cap members all had a dull, angled, grainy appearance consistent with overstress separation. The lack of deformation of the lower spar cap members, the bending deformation of the upper spar cap members, and the appearance of the fracture faces on the individual members are consistent with a tension overload failure of the lower spar cap and compression overload failure of the upper spar cap. The evidence is consistent with the separation of the left wing due to a positive overload condition.
Although flocks of migrating birds were seen in the area about the time of the accident, no evidence was found indicating that an in-flight bird strike occurred. However, it is likely that the pilot made an abrupt maneuver, possibly to avoid birds, which resulted in excessive g forces on the wing structure and led to its separation. An autopsy of the pilot did not reveal any medical conditions that might have contributed to the accident.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The pilot’s abrupt maneuver, which exceeded the structural limits of the left wing and resulted in its in-flight separation.
HISTORY OF FLIGHT
On November 27, 2013, about 1150 central daylight time, a Biesemeier manufactured Smyth Sidwinder experimental homebuilt airplane, N3786A, registered to the pilot, was destroyed when it impacted terrain after an in-flight separation of it's left wing while maneuvering over a rural area near Boulder, Colorado. The private pilot, who was the sole occupant, sustained fatal injuries. The personal flight was being conducted under the provisions of Code of Federal Regulations Part 91. Visual meteorological conditions prevailed throughout the area and a flight plan was not filed. The flight originated about 1130 from the Rocky Mountain Metropolitan Airport (BJC), and it's intended destination was Loveland, Colorado.
During examination on site, the airplane's fuselage was found in a creek bed. The left wing of the airplane was located about 1/3 of a mile from the main wreckage. The wreckage was recovered to a secure facility in Greeley, Colorado for further examination.
Radar data showed a normal departure and climbout from Rocky Mountain Airport during the first 15 minutes of flight, until a sudden turn and rapid descent. A witness in the area reported that he heard a loud sound, looked up, and saw the airplane falling out of the sky. Another witness reported that there were flocks of migrating birds in the area about the time of the accident. No radio calls or distress transmissions were reported from the pilot.
When the NTSB investigator arrived on-scene later in the day, he observed flocks of migrating birds in the area. Recovery of the airplane wreckage was accomplished on the day after the accident. Flocks of migrating birds were observed on that day as well.
PERSONNEL INFORMATION
The pilot held a valid FAA Private Pilot certificate with an Airplane Single Engine Land rating. He also held a valid FAA Mechanic Airframe & Powerplant certificate. His total flight experience, as reported on his most recent FAA medical application, was about 1,977 hours. The FAA issued the pilot a Third Class Medical Certificate on June 4, 2013. The certificate had an annotation that the pilot "must wear corrective lenses." No pilot logbooks were located during the investigation. According to an associate of the pilot, he had about 900 hours in the accident airplane and flew it about once a week.
AIRCRAFT INFORMATION
The pilot had built and owned the airplane since 1981. The airplane was issued its Experimental Amateur-Built airworthiness certificate on April 7, 1982. Build records that were provided exhibited detail and all maintenance logs were current and up to date. The two seat (side-by-side) airplane was powered by a Lycoming O-360 series reciprocating engine.
Documentation found with the maintenance logs showed that the Sidewinder design was conceived in the mid 1960s by a formal Naval fighter pilot. Contemporaries of the Sidewinder would be airplanes such as the Tailwind, T-18, Cavalier, and Mustang II. Its attributes included; fighter-like control response, a smooth aerodynamic look, and easy handling for low time pilots. Its design could accommodate limited aerobatics at plus-6 and minus-3 Gs. It's maximum cruise speed was 150 miles per hour.
The wings are all metal with built-up, riveted spars, formed aluminum ribs, and internal fiberglass wing fuel tanks. The wings are similar in design to the Mustang II, T-18, or RV-6. The airfoil is a NACA 64-212 laminar flow. There are 11 ribs in each wing, formed over wood blocks, and each rib is unique because the wing is tapered.
WRECKAGE AND IMPACT INFORMATION
The main wreckage was located along the side of a creek at grid coordinates: N40 03.740, W105 05.731. The separated left wing was located about 1,156 feet from the main wreckage on an 152 degree azimuth. The entire main wreckage was completely destroyed from impact forces. Control cable continuity was established from the flight control surfaces in the empennage and right wing forward to the cockpit controls. The breaks noted in the flight control cables were consistent with stretching and overload breaks upon impact. After on scene documentation of the main wreckage in-situ, the left wing was moved next to the fuselage to accomplish flight control continuity examination. The breaks on the flight control cables outboard to the left wing were consistent with stretching and overload breaks upon wing separation. Examination of the engine did not reveal any mechanical anomalies. Examination of the propeller assembly showed that the wooden propeller blades were severely fractured consistent with rotation/power upon impact. Examination of the separated left wing revealed that the lower left spar cap was found fractured about 8 inches outboard of the wing-to-fuselage attach point. The fracture appeared to exhibit overload evidence and the components were retained for further examination.
There was no evidence found of an in-flight bird strike.
TESTS AND RESEARCH
The main spar at the inboard end was a simple built up structure consisting of 8 aluminum straps on both the upper and lower spar caps with a thinner web installed between. Four straps are installed on the forward side of the web and four are installed on the aft side. Steel fittings are installed on the forward and aft sides of the spar caps at the inboard end to produce a clevis fitting for installation of the wing on the airplane. The clevis fittings mate with lugs at the airplane side-of-body with a shear bolt installed to attach the main spar to the fuselage.
The left lower spar cap fractured about 8 inches outboard of the attach point through the two rivet holes immediately outboard of the fittings. The lower shear bolt remained intact and installed in the fuselage with the section of lower spar cap attached. There was no obvious deformation of the lower spar cap members in the area of fracture. The upper spar cap members were fractured between 10 and 12 inches outboard of the attach point with significant S-type bending of the members in the area of fracture. The upper shear bolt remained intact and installed but the lug portion of the fuselage fitting was fractured.
The fracture faces on the upper spar cap members all had a dull, angled, grainy appearance consistent with over stress separation. There were some small areas of smearing on the fracture faces consistent with fracture face re-contact. There was no evidence of pre-existing cracks on any of the members. The fracture faces on the lower spar cap members all had a dull, angled, grainy appearance consistent with over stress separation. There was no evidence of preexisting cracks on any of the members.
The lack of deformation at the lower spar cap fracture and the appearance of the fracture faces of the individual members is consistent with a tension overload failure of the lower spar cap. The bending deformation of the upper spar cap members and the appearance of the fracture faces of the individual members is consistent with a compression overload failure of the upper spar cap. Taken together the evidence is consistent with the separation of the left wing due to a positive overload condition. There was no evidence of pre-existing conditions that would contribute to the separation.
MEDICAL AND PATHOLOGICAL INFORMATION
An autopsy of the pilot was performed by the Office of the Boulder County Coroner on February 1, 2014, and the cause of death was listed as "Multiple Blunt Trauma Injuries." Toxicology tests performed by the FAA Civil Aeromedical Institute were negative for drugs, alcohol, and carbon monoxide.
ADDITIONAL INFORMATION
The airplane wreckage was released to the owner's representative.
http://registry.faa.gov/N3786A
NTSB Identification: CEN14FA072
14 CFR Part 91: General Aviation
Accident occurred Wednesday, November 27, 2013 in Boulder, CO
Aircraft: BIESEMEIER DAVID I SMYTH SIDEWINDER, registration: N3786A
Injuries: 1 Fatal.
This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
On November 27, 2013, about 1150 central daylight time, an experimental homebuilt airplane, N3786A, registered to the pilot, was destroyed when it impacted terrain after an in-flight separation of it's wing while maneuvering over a rural area near Boulder, Colorado. The private pilot, who was the sole occupant, sustained fatal injuries. The personal flight was being conducted under the provisions of Code of Federal Regulations Part 91. Visual meteorological conditions prevailed throughout the area and a flight plan was not filed. The flight originated about 1130 from the Rocky Mountain Metropolitan Airport (BJC), and it's intended destination was Loveland, Colorado.
During examination on site, the airplane's fuselage was found in a creek bed. The left wing of the airplane was located about 1/3 of a mile from the main wreckage. The wreckage was recovered to a secure facility in Greeley, Colorado for further examination.
Radar data showed a normal departure and climbout from Rocky Mountain Airport during the first 15 minutes of flight, until a sudden turn and rapid descent. A witness in the area reported that he heard a loud sound, looked up, and saw the airplane falling out of the sky. No radio calls or distress transmissions were reported from the pilot.
Love of flying kept Loveland pilot aloft: David Biesemeier, who died in crash Wednesday, built his own plane 32 years ago
Loveland resident Dave
Biesemeier flies his Smyth Sidewinder airplane along Colorado's Front
Range in this picture provided by his wife, Lyne. Dave Biesemeier died
Wednesday, Nov. 27, 2013, when the plane that he built crashed in a
field near Erie.
LOVELAND -- On the last day of his life, David Biesemeier flew to Broomfield to help a friend with an airplane, had lunch with his pilot buddies and climbed into the plane he built 32 years ago for the trip back home to Loveland.
He made it as far as Erie, where his single-engine Smyth Sidewinder crashed in Boulder County open space near North 109th Street about 12:45 p.m. Wednesday, Nov. 27.
"He was a very helpful person," his wife, Lyne Biesemeier, said Monday. "He would do anything to help anybody with their airplanes."
Dave, as he liked to be called, had been flying since 1976, Lyne said. Shortly after getting his private pilot's license, he started building the Sidewinder at their Denver home.
"First we had to build a garage before we could build the plane," she recalled.
It took them four years, following a set of plans, with Lyne doing most of the riveting of the aluminum skin to the steel-tube frame.
Active in retirement, Dave, 66, loved to hike with Lyne in Rocky Mountain National Park, and he rode his bicycle "all over," she said. But his biggest love was flying.
"He flew that plane at least a couple of times a week," Lyne said. Every Saturday, Dave and a group of friends would pick a destination in Colorado or a neighboring state and fly there for breakfast. On Wednesdays, he would fly to Broomfield for lunch at the airport with his friends.
He had taken the two-seater as far west as San Francisco and as far east as Kitty Hawk, N.C., for the Experimental Aircraft Association's AirVenture Cup Race to Oshkosh, Wis.
Lyne said she never really liked riding in the plane she helped build because, although it was a two-place aircraft, it was cramped. "I didn't fly in it very much."
But she didn't mind that her husband flew so often. "He was a great pilot," she said, and had logged about 1,900 hours in the plane.
Dave retired in 2003 as a tool and die maker after 29 years at Coors Brewing Co.'s container business in Golden. He combined his love of airplanes and his mechanical skill in his volunteer role as a technical counselor for the Experimental Aircraft Association (EAA) chapters in Broomfield and Loveland.
"He would go out and inspect other people's planes as they were building them, to make sure they were building them right," she said, and he also did inspections for people who were buying experimental planes.
An experimental plane, she explained, is one built from a kit or from plans, rather than at a factory - the "experimental" doesn't necessarily mean it's an unproven design.
On Wednesday, he had flown down to Rocky Mountain Metropolitan Airport in Broomfield to help with the friend's plane and then had his customary lunch with friends.
"He was flying back up here when the accident happened," Lyne said.
The National Transportation Safety Board is investigating the crash, but it hasn't issued a preliminary report yet.
"We don't know what happened," Lyne said. "There's speculation that it could have been a bird strike in that area.
"We may never know what happened," she said.
Dave Biesemeier, a native of Denver, is survived by his wife of 45 years, Lyne, two children, two grandchildren and two sisters.
Lyne said they plan to have a memorial service for Dave next summer at the Fort Collins-Loveland Municipal Airport.
Story and Photo: http://www.reporterherald.com
BOULDER COUNTY - The Boulder County Coroner's Office identified the 66-year-old pilot killed in a plane crash Wednesday.
Loveland resident David Biesemeier died when his plane crashed to the ground in open space in the 4900 block of North 109th Street.
According to the FAA, the airplane was an experimental Smyth Sidewinder, a homebuilt kit aircraft.
The sheriff's office confirmed the plane had pieces falling off of it when it went down Wednesday afternoon.
Witnesses said they heard a large explosion just before the plane began to break apart.
Crews on the scene say Biesemeier was the only person on board.
A dive team was also working the scene because the craft was partially in the water.
The FAA and the NTSB are investigating this incident.
Biesemeier was the current president of the Experimental Aircraft Association Chapter 43.
The association's vice president, Lynn Miller, said that Biesemeier built the plane that crashed.
Miller said that Biesemeier was a wonderful man dedicated to flying.
A piece of the Smyth Sidewinder plane that crashed
Rescuers responded about 12:45 p.m. Wednesday to a plane crash on open space at 4900 N. 109th St. in Boulder County.
A witness called 911 and reported seeing the crash.
The downed plane is east and slightly north of the washed out bridge on 109th Street.
The Boulder County Sheriff's Office confirmed at least one fatality, the pilot of the plane.
Kira Cady, who lives on Lookout Road about a mile from the crash site, said she was cleaning up after her horses when she saw the plane.
"I saw the left wing of the plane fall off, it looked like half to three-fourths. I heard the engine and then the wing broke, and then I saw debris going down. I immediately called 911."
Kira Cady, who lives on Lookout Road about a mile from the crash site, said she was cleaning up after her horses when she saw the plane.
"I saw the left wing of the plane fall off, it looked like half to three-fourths. I heard the engine and then the wing broke, and then I saw debris going down. I immediately called 911."
Heard a "kaboom" at the end after the plane went down.
"It was crazy. I was crossing my fingers that he was going to end up alive."
Lori Greene, who lives at 4998 109th, just north of crash site, said she heard what sound like an explosion at 12:47 p.m. She knows the exact time because she was on her computer.
"I have animals, so I went to make sure no car had hit them. And when I came out, I saw debris in my neighbor's yard," she said.
That debris includes two long metal chunks. On her own property, she found smaller pieces of metal, glass and blue styrofoam, as well as an air sickness bag.
"I certainly didn't think a plane had exploded and fallen out of the sky, but it didn't sound like a car accident.
There were no tires screeching or anything like that. ... When I saw the motion sickness bag in my own yard, that's when I knew."
Greene said that on warm days and weekends, there's usually a pilot overhead, sometimes doing aerobatics.
The Boulder County Sheriff's Office identified the plane as a Smyth Sidewinder, a homebuilt, kit aircraft.
A plane tracker on the Denver International Airport website shows a general aviation aircraft heading north into the crash area around 12:45 p.m. The plane abruptly disappears from the tracker at that time.
Boulder County Sheriff's deputies, Colorado State Patrol, Mountain View Fire Protection and Lafayette police and fire were all on the scene of the crash, which happened a few hundred feet east of the road in a "washed out area" in or near Boulder Creek. National Transportation Safety Board investigators were expected on the scene around 4 p.m.
"It was crazy. I was crossing my fingers that he was going to end up alive."
Lori Greene, who lives at 4998 109th, just north of crash site, said she heard what sound like an explosion at 12:47 p.m. She knows the exact time because she was on her computer.
"I have animals, so I went to make sure no car had hit them. And when I came out, I saw debris in my neighbor's yard," she said.
That debris includes two long metal chunks. On her own property, she found smaller pieces of metal, glass and blue styrofoam, as well as an air sickness bag.
"I certainly didn't think a plane had exploded and fallen out of the sky, but it didn't sound like a car accident.
There were no tires screeching or anything like that. ... When I saw the motion sickness bag in my own yard, that's when I knew."
Greene said that on warm days and weekends, there's usually a pilot overhead, sometimes doing aerobatics.
The Boulder County Sheriff's Office identified the plane as a Smyth Sidewinder, a homebuilt, kit aircraft.
A plane tracker on the Denver International Airport website shows a general aviation aircraft heading north into the crash area around 12:45 p.m. The plane abruptly disappears from the tracker at that time.
Boulder County Sheriff's deputies, Colorado State Patrol, Mountain View Fire Protection and Lafayette police and fire were all on the scene of the crash, which happened a few hundred feet east of the road in a "washed out area" in or near Boulder Creek. National Transportation Safety Board investigators were expected on the scene around 4 p.m.
Story and Photos: http://www.timescall.com
