ATL95FA092

Reports from ground witnesses, none of whom actually saw the airplane, varied from hearing a high revving engine to an explosion. Examination of the wreckage revealed that the airplane experienced an in-flight breakup. Damage and structural deformation was indicative of aileron-wing flutter. Wing fabric dope was distressed or missing on the aft inboard portion of the left wing upper surface and along the entire length of the top of the main spar. Large areas of dope were also missing from the left wing undersurface. The entire fabric covering on the upper and lower surfaces of the right wing had delaminated from the wing plywood skin. The doped finish was severely distressed and mottled. The fabric covering had not been installed in accordance with the poly-fiber covering and paint manual; the plywood was not treated with the poly-brush compound.

History of flight

On April 27, 1995, about 1210 central daylight time, a Wittman O&O (Ocala and Oshkosh) experimental airplane, N41SW, registered to a private owner, operating as a 14 CFR Part 91 personal flight, experienced an in-flight breakup about 7 miles south of Stevenson, Alabama. Visual meteorological conditions prevailed and no flight plan was filed. The commercial pilot and pilot-rated passenger were fatally injured. The airplane was destroyed. The flight originated about 2 hours 40 minutes before the accident. The airplane was reported overdue on April 28, 1995, and was located on April 29, 1995.

According to friends of the pilot, this was his annual return flight to Oshkosh, Wisconsin. One of the friends stated that he conducted a preflight inspection of the airplane, and did not discover any problems. According to another friend, the pilot had planned his flight to avoid flying through controlled airspace, and the need to establish radio contact. The flight departed without incident. No radio communication was reported between air traffic and the flight.

At the approximate time of the accident, several local residents reported hearing an airplane in the vicinity of the accident site. These witnesses were located in a valley and on a mountain ridge; none of the witnesses actually saw the airplane in flight. Their accounts varied from hearing a high revving engine to hearing an explosion. One witness at the Stevenson Airport reported hearing a sonic boom, but did not see or hear a jet aircraft in the vicinity of the airport. According to Memphis Air Route Traffic Control Center, there were no military aircraft operating on the military training routes at the approximate time of the accident.

On April 28, 1995, friends of the pilot became concerned about the location of the airplane, since it never arrived at the planned destination. The Federal Aviation Administration (FAA) issued an alert notice, and a search for the missing airplane was initiated. On April 29, 1995, at 1830, debris from N41SW was located in the vicinity of strip mines, south of Stevenson. A massive ground and aerial search located the main wreckage early the following morning.

Personnel information

Information about the pilot is included in this report under the data field labeled "First Pilot Information". A review of the pilot's airmen records disclosed that he had acquired several pilot ratings which included certified flight instructor. The pilot had also held an airframe and powerplant (A & P) mechanic's rating. The pilot's flight logs were not recovered for examination.

Medical history on the pilot was limited, since his attending physician died several months before this accident. A review of the pilot's FAA medical records failed to disclose a dramatic shift in the pilot's medical condition. During his last flight physical examination, the pilot had an elevated blood pressure reading. The pilot was requested to provide additional medical information to the FAA Aeromedical Division. On May 12, 1995, the FAA reviewed the additional data and declared that Mr. Wittman was medically qualified to hold a second class airmen medical certificate. According to friends of the pilot, he maintained a fit lifestyle, and they could not recall any extended medical treatment the pilot had received in recent years.

Information on the second pilot is included in this factual report as NTSB Form 6120.4, Supplement E.

Aircraft information

Information about the aircraft is included in this report under the data field labeled "Aircraft Information". According to the chairman and founder of the EAA, the Wittman O & O experimental airplane was a one-of-a-kind aircraft, and there was no design or performance information available for airplane. A review of aircraft data revealed that Mr. S.J. Wittman was issued the experimental operating limitations for the O & O experimental airplane on January 6, 1985.

Meteorological information

Visual meteorological conditions prevailed at the time of the accident. Weather information is contained in this report under the data field labeled "Weather Information". According to the weather study conducted by the National Transportation Safety Board, the 1200 weather plot showed southwest surface winds with wind speeds variable between 10 and 20 knots. Upper level winds between the surface and 10,000 feet in the vicinity of the accident site, were out of the southwest between 15 and 20 knots. The weather study also concluded that no significant wind shear was likely, but occasional light to moderate low level turbulence was possible in the vicinity of the accident site.

Wreckage and impact information

Debris from the airplane was scattered in a ravine over an area 1.25 miles long, on Sand Mountain (see the wreckage distribution diagram). Examination of the accident site and wreckage disclosed that the airplane separated into four major components: both wings, the empennage section, and the main fuselage. They were scattered within an area .25 miles long. Other wreckage debris was scattered over an additional mile.

Examination of the accident site disclosed that wreckage debris was scattered on a southwesterly heading. The first pieces of the wreckage debris were found in the coal mining area near the location of the emergency management command post (see the wreckage diagram). A piece of aircraft skin, with the letters O and O printed on it was recovered with the debris near the coal mines. This piece of skin material was subsequently identified as part of N41SW. Other debris located in the vicinity of the strip coal mines included plexiglass material and yellow painted fabric material. The southwest trail of debris, which included aircraft fabric, paint chips, personal items of the occupants, and flight charts, continued for about a mile where the larger pieces of the airframe were located.

The left wing assembly was located in a heavily wooded area about a mile southwest of the wreckage debris at the mining area. The left wing was located on a steep ridge near a creek. An examination of the left wing assembly disclosed that the main wood spar was fractured through the lateral plane of the bolted wing-to-fuselage attachment fitting. The fracture plane extended from the inboard end of the spar about 34 inches outboard.

The front wing-to-fuselage spar attachment fitting was bent aft about 3 degrees and twisted about 5 degrees in the wing leading edge down direction. Both the front and the rear wing-to-fuselage spar attachment fittings exhibited damage, eg., twisting, bending, rear wood spar fracture, or damage to fuselage clevis tang attachment webs.

About 6 inches of the wing lift strut stub remained attached to the fuselage. The lift strut exhibited some slight column buckling (downward) about 16 inches from the spar attachment fitting.

The left wing aileron and flap were missing in their entirety. The outboard aileron hinge attachment bolt/washer had broached a clean round hole, about 1-inch in diameter, through the secondary (false) rear spar and hinge block.

The entire wing tip structure assembly (including dope/fabric) was relatively intact and remained attached to the remainder of the wing. The fabric remaining on the top and bottom surfaces of the wing was, for the most part, doped in place except in those areas adjacent to the wing skin fracture lines. The dope was distressed or missing on the aft inboard portion of the wing upper surface and along the entire length of the top of the main spar.

The right wing was located on the mountain ridge about 200 yards southwest of the left wing assembly. The main wood spar was cracked/split through the lateral plane of the bolted wing-to-fuselage attachment fitting. The primary fracture plane extended from the inboard end