{"as_of":"2026-10-07","attribution":"FAA and NTSB data via eFlight Registry (https://eflight.com)","connections":[{"group":"Covers","items":[{"count":125,"name":"Franklin 4AC176B series","note":"","unit":"aircraft","url":"https://eflight.com/engines/franklin-4ac176b-series"}],"relation":"covers"},{"group":"Held by","items":[{"count":null,"name":"Franklin Engine Company","note":"","unit":"","url":"https://eflight.com/holders/franklin-engine-company"}],"relation":"held by"},{"group":"More","items":[{"count":null,"name":"Every type certificate","note":"","unit":"","url":"https://eflight.com/certificates"},{"count":null,"name":"Who holds what","note":"","unit":"","url":"https://eflight.com/holders"}],"relation":"see also"}],"graph":"https://eflight.com/graph","graph_index":"https://eflight.com/graph/index.json","license":"https://creativecommons.org/licenses/by/4.0/","node":{"faa_document":"https://drs.faa.gov/browse/excelExternalWindow/F53083F2E12063B58525670C005652F3.0001","holder":"Franklin Engine Company","id":"TC 221","models":["4AC-176 Series"],"name":"Type certificate TC 221","product_type":"Engine","type":"certificate","url":"https://eflight.com/certificates/TC 221"},"source":"FAA Civil Aviation Registry, FAA airport file, NTSB accident database; assembled by eFlight Registry"}