# NTSB CEN14LA507: Manweiller Acro Sport II, N94SM, Middletown, OH, September 20, 2014 - Type: NTSB accident investigation - Classification: Accident · Fatal · Limited investigation · Final report - Date: September 20, 2014, 08:57 local (12:57 UTC) - Place: Middletown, OH - Coordinates: 39.418334, -84.362503 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.4183&lon=-84.3625&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-aerobatics: Loss of control in flight](https://openairdocs.org/ntsb-events/240) - Highest injury: Fatal - Injuries: 2 fatal - Status: Completed, report June 9, 2015 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Federal Aviation Administration, Lycoming Engines - NTSB case key (mKey): 90109 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN14LA507 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/90109/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=90109 - Page: https://openairdocs.org/ntsb/CEN14LA507 ## Probable cause The failure of the flying pilot to maintain airplane control after an aerodynamic stall/spin occurred during the aerobatic maneuver following a reported intermittent loss of engine power for reasons that could not be determined during postaccident examinations. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating)](https://openairdocs.org/ntsb-findings/01058500): Aircraft › Aircraft power plant · Malfunction (probable cause); cases with it: [Manweiler Steven R ACRO SPORT II, 1 case](https://openairdocs.org/ntsb-findings/01058500/cases.md?model=05624N8), [All aircraft, 497 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Manweiler Steven R ACRO SPORT II, 1 case](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=05624N8), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Manweiler Steven R ACRO SPORT II, 1 case](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=05624N8), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md) - [Performance/control parameters: angle of attack](https://openairdocs.org/ntsb-findings/01062042): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Manweiler Steven R ACRO SPORT II, 1 case](https://openairdocs.org/ntsb-findings/01062042/cases.md?model=05624N8), [All aircraft, 990 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-aerobatics: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342); cases with it: [Manweiler Steven R ACRO SPORT II, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=05624N8), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Maneuvering-aerobatics: Loss of control in flight](https://openairdocs.org/ntsb-events/240) (defining event); cases with it: [Manweiler Steven R ACRO SPORT II, 1 case](https://openairdocs.org/ntsb-events/240/sequence.md?model=05624N8), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Manweiler Steven R ACRO SPORT II, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=05624N8), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot and pilot-rated passenger were flying a local flight and performing aerobatic maneuvers in the experimental amateur-built airplane. A witness reported that she heard the airplane approaching and then saw it and noted that it was at a lower altitude than she normally saw aircraft in the area. The airplane then started to pitch nose up into a loop. As the airplane reached the top of the looping maneuver, the sound of the engine stopped, and the airplane then immediately started descending. The airplane then entered a spiral/spin, and the witness lost sight of the airplane behind some trees. She then heard the sound of an engine, consistent with the pilot adding engine power, followed immediately by the sound of impact. The airplane was engulfed in flames upon her arrival. The witness demonstrated what she had seen with a model airplane, and the demonstration was consistent with an attempted loop with a spin out of the top of the maneuver. Witness marks at the accident site revealed that the airplane was producing power at the time of impact. An examination of the engine and flight controls did not reveal any preimpact anomalies that would have precluded operation. A weight and balance calculation showed that the airplane was within its published limits. The airplane likely experienced an aerodynamic stall at the top of the looping maneuver and then entered a spin from which the flying pilot was not able to recover. The investigation could not determine which occupant was manipulating the controls during the flight. ## Factual narrative The investigation could not determine which airplane occupant was manipulating the flight controls during the accident flight. N94SM was a plans-built, experimental, amateur-built Manweiler Acro Sport II airplane with serial number 733. The airplane's plan included a short wing span biplane design with a conventional tail wheel configuration, open cockpits, and faring covered fixed main landing gear. Its structure was a fabric-covered steel tube fuselage and empennage group with a wood wing structure. A 200-horsepower Lycoming IO-360-A1A engine, with serial number L-17470-51A, powered the airplane. Review of an FAA 8050-2 bill of sale form revealed that the airplane was purchased on July 26, 2014. According to an owner's representative, the airplane last condition inspection was completed on August 28, 2014 and it accumulated 596 hours of total flight time at the time of that inspection. The impacted house did not reveal any discoloration. The localized area where the airplane came to rest exhibited discoloration and charred vegetation consistent with a ground fire. On September 20, 2014, about 0857 eastern daylight time, an experimental amateur-built Manweiler Acro Sport II airplane, N94SM, impacted buildings and terrain near Middletown, Ohio, and a ground fire subsequently occurred. Both airplane occupants were private pilots and were fatally injured. The airplane sustained substantial damage. The airplane was registered to and operated by Biplane Crazy LLC under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Day visual flight rules conditions prevailed for the flight, which did not operate on a flight plan. The local flight originated from the Butler County Regional Airport-Hogan Field (HAO), near Hamilton, Ohio, about 0830. A Federal Aviation Administration (FAA) inspector interviewed a witness, who was outside in her driveway, when she heard the aircraft approaching. She said it was at a lower altitude than she normally sees aircraft in the area. As it was coming toward her from east to west it started to pitch, nose up, into what she said looked like a loop. As it got to the top of the looping maneuver, and an instant before it started down, the sound of the engine stopped. The aircraft then entered a spiralling, spinning maneuver, which continued until she lost sight of the aircraft behind some trees. She then heard the sound of an engine, consistent with the pilot adding engine power, followed immediately by the sound of impact. She told her husband to call 911 and report the accident. She then "grabbed" a neighbor, who is an EMT, and went to the crash site to try to help. The aircraft was engulfed in flames when they arrived, and they were unable to help. The inspector had her demonstrate what she saw with a model airplane. The demonstration was consistent with an attempted loop with a spin out of the top of the maneuver. An autopsy was performed on the front seated pilot by the Butler County Coroner'sOffice. The autopsy indicated that injuries sustained during the accident were the cause of his death. An autopsy was performed on the rear seated pilot rated passenger by the Butler County Coroner's Office. The autopsy indicated that cranial trauma was the cause of his death. The FAA Civil Aerospace Medical Institute prepared Final Forensic Toxicology Accident Reports for both pilots from samples taken during their autopsies. The report on each pilot was negative for the tests performed. At 0853, the recorded weather at HAO was: Wind calm, visibility 6 statute miles; present weather mist; sky condition few clouds at 4,700 feet; temperature 16 degrees C; dew point 13 degrees C; altimeter 30.10 inches of mercury. The 49-year-old pilot in the front seat held a FAA private pilot certificate with airplane single engine land and instrument airplane ratings. He held a FAA Third Class Medical Certificate issued on November 12, 2013. This medical certificate was issued without any limitations. The pilot reported on the application for that medical certificate that he had accumulated 1,525 hours of total flight time and 75 hours in the six months prior to the medical examination. This pilot's reported weight was 187 pounds at the time of the medical examination. The pilot recorded in his logbook that he had accumulated 1,662.1 hours of total flight time, 41 hours of flight time in the 90 days prior to the accident, 12 hours of flight time in the 30 days prior to the accident, and 6 hours of flight time in the accident airplane. The 40-year-old pilot rated passenger in the rear seat held a FAA private pilot certificate with an airplane single engine land rating. He was issued a FAA Third Class Medical Certificate on June 4, 2008. This medical certificate was issued without any limitations. The pilot reported on the application for that medical certificate that he had accumulated 900 hours of total flight time and 0 hours in the six months prior to the medical examination. This pilot's reported weight was 232 pounds at the time of the medical examination. The pilot recorded in his logbook that he had accumulated 906.5 hours of total flight time, 24.5 hours of flight time in the 90 days prior to the accident, 2 hours of flight time in the 30 days prior to the accident, and 2 hours of flight time in the accident airplane. The wreckage was recovered to a storage facility. An FAA inspector and an air safety investigator from the engine manufacturer examined the accident engine on October 7, 2014. There was evidence of a post impact fire resulting in engine damage. A thumb compression was observed on undamaged cylinders. Damaged cylinders were removed and inspected, where no damage to valves, pistons, rings, or cylinder walls were noted. Crankshaft continuity was confirmed by observing accessory gear rotation at the rear of the engine and movement of each piston and its rod while rotating the propeller hub by hand. Camshaft continuity was confirmed when thepropeller hub was rotated by hand. All intake and exhaust valves moved through the opening and closing sequence. No preimpact anomalies were detected that would have precluded engine operation. Radar return data was gathered by a National Transportation Safety Board air traffic control specialist. The specialist produced an illustration that depicted the accident flight's path. The illustration is appended to the docket material associated with this case. A weight and balance calculation was conducted using a weight and balance worksheet dated August 6, 1994, which was forwarded by an airplane owner's representative. Assuming no weight in the baggage compartment, the calculation, using the pilot and pilot rated passengers weight listed on their last medical forms plus 15 pound parachutes, revealed that the airplane was below the maximum "allowable" weight listed on the worksheet and within the maximum and minimum center of gravity limit, at both maximum and minimum fuel amounts. The airplane impacted buildings about 200 feet northeast of the intersection of Willow Creek Drive and Sunrise View Circle. FAA inspectors examined and documented the accident site and wreckage. The exterior wall of garage near where the airplane came to rest exhibited an opening and slash marks consistent with an airplane with a rotating propeller breaching that wall. The airplane came to rest upright in the rear yard of the house. The airplane, forward of its empennage, was discolored, deformed, and charred, with sections consumed by fire. The inspectors' examination and review of their accident site pictures did not reveal any preimpact flight control anomalies that would have precluded operation of the airplane. ## Aircraft - Registration: [N94SM](https://openairdocs.org/deregistered/N94SM-2018-04-18), registration cancelled 2018-04-18, S/N 733, built 1994 (OpenAirDocs) - Reported make and model: MANWEILLER ACRO SPORT II - Registry model: [Manweiler Steven R ACRO SPORT II](https://openairdocs.org/model/manweiler-steven-r-acro-sport-ii) (registry code 05624N8) (OpenAirDocs) - Registry engine: [Lycoming I0360 SER A&C](https://openairdocs.org/engine/lycoming-i0360-ser-a-c) (registry code 41511, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 733 - Year built: 1994 - Airframe hours: 596 - Engines: LYCOMING IO-360-A1A 200 horsepower reciprocating - Damage: Substantial damage - Fire: On-Ground - Flight: Personal, Part 91 - Operator: Biplane Crazy, LLC - Registered owner: Biplane Crazy, LLC - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, August 28, 2014 - Departed: HAO, HAMILTON, OH - Destination: HAO, HAMILTON, OH ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 49; injuries: fatal; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, without waivers/limitations; last flight review May 3, 2014; seat: front; toxicology performed; flight hours: 1,662 total, 6 in this make and model, 41 in the last 90 days, 12 in the last 30 days - Pilot-rated passenger; age 40; injuries: fatal; private; airplane ratings: single-engine land; medical: class 3, without waivers/limitations; last flight review May 14, 2014; seat: rear; toxicology performed; flight hours: 906.5 total, 2 in this make and model, 24.5 in the last 90 days, 2 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 6 statute miles - Lowest ceiling: none - Temperature: 61 °F, dew point 55 °F - Altimeter: 30.10 inHg - Observed at: KHAO, 8 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20140920016769A](https://openairdocs.org/incident/20140920016769A), Sep 20, 2014: Manweiler Steven R ACRO SPORT II, Monroe, OH, Destroyed, 2 fatal. Pilots were out practicing aerobatics. On the way back to their home base they unsuccessfully attempted a maneuver which led them to crash in a residential… ## Other investigations on N94SM (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB FTW03LA167](https://openairdocs.org/ntsb/FTW03LA167), Jun 7, 2003: Manweiler Acro Sport II (N94SM), Bartlesville, OK, substantial damage. Probable cause: The pilot's inadequate preflight inspection, which resulted in fuel exhaustion. A related factor was the lack of suitable terrain. ## Docket (16 files) The files NTSB released with the investigation on May 6, 2015, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=90109. 8.7 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425652&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Communication Summary - Mary Runnebaum (item 2, .PDF, 81 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425653&FileExtension=.PDF&FileName=Communication%20Summary%20-%20Mary%20Runnebaum-Master.PDF - Communication Summary - Engine (item 3, .PDF, 87 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425654&FileExtension=.PDF&FileName=Communication%20Summary%20-%20Engine-Master.PDF - Front Seat Pilot Logbook Excerpts (item 4, .PDF, 2.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425655&FileExtension=.PDF&FileName=Front%20Seat%20Pilot%20Logbook%20Excerpts-Redacted.PDF - Rear Seat Pilot Logbook Excerpts (item 5, .PDF, 720 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425656&FileExtension=.PDF&FileName=Rear%20Seat%20Pilot%20Logbook%20Excerpts-Redacted.PDF - EAA Acro Sport Specifications (item 6, .PDF, 275 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425657&FileExtension=.PDF&FileName=EAA%20Acro%20Sport%20Specifications-Master.PDF - Mini SOFTIE - Emergency Parachutes (item 7, .PDF, 74 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425658&FileExtension=.PDF&FileName=Mini%20SOFTIE%20-%20Emergency%20Parachutes-Redacted.PDF - FAA Witness Statement (item 8, .PDF, 293 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425659&FileExtension=.PDF&FileName=FAA%20Witness%20Statement-Redacted.PDF - FAA Witness Model Demonstration (item 9, .PDF, 167 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40426382&FileExtension=.PDF&FileName=FAA%20Witness%20Model%20Demonstration-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 10, .PDF, 72 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425660&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF - Weight and Balance Calculation (item 11, .PDF, 337 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425661&FileExtension=.PDF&FileName=Weight%20and%20Balance%20Calculation-Master.PDF - Wreckage Release (item 12, .PDF, 146 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425666&FileExtension=.PDF&FileName=Wreckage%20Release-Redacted.PDF - Toxicological Report - Steven Krummen (item 13, .PDF, 136 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425662&FileExtension=.PDF&FileName=Toxicological%20Report%20-%20Steven%20Krummen-Master.PDF - Toxicological Report - Jeffrey Krummen (item 14, .PDF, 136 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425663&FileExtension=.PDF&FileName=Toxicological%20Report%20-%20Jeffrey%20Krummen-Master.PDF - Overview of Flight Path (item 15, .PDF, 375 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425664&FileExtension=.PDF&FileName=Overview%20of%20Flight%20Path-Master.PDF - Photo 1 - Impacted House (Photo Courtesy of FAA) (item 16, .PDF, 153 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40425665&FileExtension=.PDF&FileName=Photo%201%20-%20Impacted%20House%20(Photo%20Courtesy%20of%20FAA)-Master.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.