What caused the crash of a small, single-engine plane in a Southwest Portland neighborhood last summer may never be known.
On board the Lancair IV Propjet were William (64) and Jeannine (63) Shepard, a couple from Idleyld Park (northeast of Roseburg) and their grandson, Benjamin, 12. All three were killed when the plane, shortly after taking off June 15 from Hillsboro Airport, crashed into a residential neighborhood just outside of Lake Oswego and Tryon Creek State Park.
The plane came down in the backyard of a residence just before 9 a.m. The crash triggered reports to the Lake Oswego Police Department and the Lake Oswego Review.
Following an almost year-long investigation by the National Transportation Safety Board, no conclusive evidence could be found for the crash. The plane, which reportedly was built from a kit, was traveling to Twin Falls, Idaho, before heading to its ultimate destination of Kansas where Benjamin was scheduled to attend a science camp.
According to the NTSB report, 'during examination of the wreckage no evidence suggesting mechanical malfunction or failure was found. However, the severity of the impact damage, which resulted in destruction of the flight control system and all flight instruments and avionics, precluded determination of the reason for the loss of control.'
The report noted that 'the last transmission received from the pilot was about 1 minute 40 seconds after takeoff when the pilot acknowledged receipt of a clearance.'
The report continued, 'about 3 minutes 23 seconds after takeoff, the airplane began to descend and entered a right turn. The last radar return was recorded about 5 minutes after takeoff and placed the airplane at 3,300 feet … about 1/4-mile east of the accident site. A witness reported seeing the airplane emerge from an overcast cloud layer in a near vertical attitude traveling at a high rate of speed. The airplane impacted in the backyard of a residence.
William Shepard was instrument rated and had accumulated about 158 hours of instrument flight time, the report said.
Officials reported there was no rain at the time and the plane did travel through various cloud layers.
According to reports, the plane's engine and propeller were found buried in an impact crater three feet below the surface. A debris field extended from 25 to 60 feet in all directions.
William Shepard was a retired Intuit executive who helped develop the Turbo Tax computer program.