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Accidents · NTSB CEN18LA173 · Final report

Grumman American Avn. CORP. AA 1B accident near Hamilton, Ohio, May 15, 2018

On May 15, 2018 at about 1:45 pm local time, a 1974 Grumman American Avn. CORP. AA 1B, registered N6550L, was substantially damaged in an accident during takeoff near Hamilton, Ohio (Butler CO Rgnl-Hogan Field). It was a flight test under general aviation rules (Part 91). 1 person was seriously injured. The weather was visual conditions (good weather).

The NTSB's probable cause their words, unchanged

The loss of engine power during takeoff for reasons that could not be determined because postaccident examination revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.

Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.

What the record shows

Date
May 15, 2018 · about 1:45 pm local time
Place
Hamilton, Ohio · Butler CO Rgnl-Hogan Field · map
Type
Accident
Injuries
1 person was seriously injured.
Weather
visual conditions (good weather)
Aircraft
Grumman American Avn. CORP. AA 1B, built 1974 · all AA 1Bs on the register
Registration
N6550L · no longer on the register · serial AA1B-0350
Damage
Substantial damage
Flight
Flight test · general aviation rules (Part 91)

The NTSB's narrative final · quoted from the NTSB record

About 1 month before the accident, the prior owner of the accident airplane performed a maintenance test flight after an engine replacement. The airplane failed a run-up because of engine roughness. The mechanic/accident pilot who performed the engine replacement felt that the roughness was caused by oil getting by the new piston rings and fouling the spark plugs. The mechanic/pilot cleaned and reinstalled the plugs. The maintenance test flight was then reattempted, and the prior owner flew in the right seat with the mechanic/pilot as the pilot flying. The prior owner indicated that the mechanic/pilot took the active runway without completing an engine run-up. The takeoff power appeared normal until about 100 ft above ground level, when the engine failed abruptly and without warning. The airplane's nose dropped, and the pilot landed the airplane, stopping it about 30 ft from the end of the runway. The mechanic/pilot subsequently sent the carburetor out for overhaul. After reinstalling the carburetor, the mechanic/pilot attempted another maintenance test flight, which was the accident flight. Witnesses stated that the airplane took off; they heard the engine stop, and the pilot attempted to circle back to the airport but did not make it. The airplane impacted terrain during the landing, which resulted in substantial damage to the wing and fuselage. The mechanic/pilot completed an accident report that did not contain a narrative of the accident flight and advised that he did not recall the accident. Further, the pilot did not indicate the date of his last flight review. A postaccident engine examination revealed no evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation. The engine monitor sustained damage; no engine data was recorded for the accident flight. At the time of the accident, the weather conditions were conducive to moderate carburetor icing at cruise power and serious carburetor icing at descent power. However, the engine was operating at takeoff power; the investigation was unable to determine if the pilot conducted any ground operations during which carburetor ice could have formed. Thus, a reason for the loss of engine power could not be determined.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.

The factual record from the NTSB's investigation tables, in plain English

What happened, in order

  1. Loss of engine power (total) during takeoff defining event
  2. Off-field or emergency landing during emergency descent
  3. Collision with terrain or object (not controlled flight into terrain) during landing

The NTSB's findings

  • cause Not determined › Not determined › (general) › (general) › Unknown/Not determined
  • Personnel issues › Experience/knowledge › Experience/qualifications › Qualification/certification › Pilot

Pilot

  • Certificate: commercial pilot, private
  • Ratings: multi-engine land; single-engine land; instrument: airplane
  • Flight time: 6,000 hours in all; 50 in this make and model
  • Medical certificate: Class 3 (with waivers/limitations)
  • Seat: left
  • Injury: serious injuries

The aircraft

  • Airframe total time: 4,126 hours
  • Last inspection: annual inspection, April 3, 2018
  • Maximum gross weight: 1,560 lb
  • Seats: 2
  • Landing gear: fixed
  • Engine: Lycoming O-235-C2C (piston); 6,758 hours total

The flight

  • Departed from: HAO Hamilton OH at 1:45 pm
  • Destination: HAO Hamilton OH
  • Flight plan: none

Weather at the time

  • Light: daylight
  • Wind: at 5 knots
  • Visibility: 10 statute miles
  • Sky: clear
  • Temperature: 79°F (26°C), dew point 63°F (17°C)
  • Altimeter: 29.93 inHg
  • Observation at 1:53 pm from KHAO

Injuries

FatalSeriousMinorNone
Flight crew1

Documents from the investigation the NTSB's docket: the evidence folder behind the report

15 documents, released by the NTSB on October 3, 2019. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.

The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.

Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.