History of Flight
On September 20, 2014, about 0857 eastern daylight time, an experimental amateur-built Manweiler Acro Sport II airplane, registration N94SM, impacted buildings and terrain near Middletown, Ohio. A ground fire subsequently occurred. Both airplane occupants, who held private pilot certificates, sustained fatal injuries. The airplane sustained substantial damage.
The airplane was registered to Biplane Crazy LLC and operated under 14 Code of Federal Regulations Part 91 as a personal flight. Day visual flight rules conditions prevailed, and the flight did not operate on a flight plan. The local flight originated from Butler County Regional Airport-Hogan Field (HAO), near Hamilton, Ohio, about 0830.
A witness reported hearing the aircraft approaching at a lower altitude than usual. She observed the airplane pitch nose-up into what appeared to be a loop. At the top of the maneuver, the engine sound stopped. The aircraft then entered a spiraling, spinning maneuver until it disappeared behind trees. She then heard engine power added, followed immediately by the sound of impact. The witness and an EMT neighbor went to the crash site, but the airplane was engulfed in flames, preventing assistance.
Personnel Information
The pilot in the front seat, age 49, held a private pilot certificate with airplane single-engine land and instrument ratings. He had a third-class medical certificate issued November 12, 2013, with no limitations. He reported 1,525 total flight hours and 75 hours in the previous six months. His logbook indicated 1,662.1 total hours, with 41 hours in the 90 days prior, 12 hours in the 30 days prior, and 6 hours in the accident airplane.
The pilot-rated passenger in the rear seat, age 40, held a private pilot certificate with an airplane single-engine land rating. He had a third-class medical certificate issued June 4, 2008, with no limitations. He reported 900 total flight hours and 0 hours in the previous six months. His logbook showed 906.5 total hours, with 24.5 hours in the 90 days prior, 2 hours in the 30 days prior, and 2 hours in the accident airplane.
Aircraft Information
N94SM was a plans-built, experimental amateur-built Manweiler Acro Sport II, serial number 733. It was a short-wing biplane with conventional tailwheel configuration, open cockpits, and fixed main landing gear. The structure consisted of a fabric-covered steel tube fuselage and empennage with wood wings. The engine was a 200-horsepower Lycoming IO-360-A1A, serial number L-17470-51A. The airplane was purchased on July 26, 2014. The last condition inspection was completed on August 28, 2014, at which time it had accumulated 596 total flight hours.
Meteorological Information
At 0853, the recorded weather at HAO was: wind calm, visibility 6 statute miles, mist, few clouds at 4,700 feet, temperature 16°C, dew point 13°C, altimeter 30.10 inches of mercury.
Wreckage and Impact Information
The airplane impacted buildings about 200 feet northeast of Willow Creek Drive and Sunrise View Circle. The garage wall showed an opening and slash marks consistent with a rotating propeller breaching the wall. The airplane came to rest upright in a rear yard. The forward section was discolored, deformed, and charred, with fire damage. Examination revealed no preimpact flight control anomalies.
Medical and Pathological Information
Autopsies performed by the Butler County Coroner's Office indicated that the front-seated pilot died from injuries sustained in the accident, and the rear-seated pilot-rated passenger died from cranial trauma. Forensic toxicology reports from the FAA Civil Aerospace Medical Institute were negative for both pilots.
Fire
The impacted house showed no discoloration. The area where the airplane came to rest had discolored and charred vegetation consistent with a ground fire.
Tests and Research
Postaccident examination of the engine found evidence of post-impact fire damage. Thumb compression was observed on undamaged cylinders. Damaged cylinders showed no anomalies in valves, pistons, rings, or cylinder walls. Crankshaft and camshaft continuity were confirmed, and all valves moved properly. No preimpact anomalies were detected that would have precluded engine operation.
Radar data from the NTSB depicted the accident flight path. A weight and balance calculation, using pilot and passenger weights from medical forms plus 15-pound parachutes, showed the airplane was below maximum allowable weight and within center of gravity limits.
Additional Information
The investigation could not determine which occupant was manipulating the flight controls at the time of the accident.