{"as_of":"2026-11-05","attribution":"FAA and NTSB data via eFlight Registry (https://eflight.com)","connections":[{"group":"Where they are","items":[{"count":1,"name":"Wisconsin","note":"","unit":"of these aircraft","url":"https://eflight.com/states/WI"}],"relation":"registered in"},{"group":"Biggest operators","items":[{"count":1,"name":"Eaa Aviation Foundation INC","note":"","unit":"of these aircraft","url":"https://eflight.com/fleets/eaa-aviation-foundation-inc"}],"relation":"owned by"},{"group":"Analytics","items":[{"count":null,"name":"The fleet by engine type","note":"","unit":"","url":"https://eflight.com/analytics/fleet"},{"count":null,"name":"Every engine series","note":"","unit":"","url":"https://eflight.com/engines"}],"relation":"compared in"}],"graph":"https://eflight.com/graph","graph_index":"https://eflight.com/graph/index.json","license":"https://creativecommons.org/licenses/by/4.0/","node":{"aircraft":1,"horsepower":40,"id":"keikhafer-mk55","maker":"Keikhafer","name":"Keikhafer MK55","thrust_lb":null,"type":"Piston (reciprocating)","url":"https://eflight.com/engines/keikhafer-mk55"},"source":"FAA Civil Aviation Registry, FAA airport file, NTSB accident database; assembled by eFlight Registry"}