{"as_of":"2026-10-07","attribution":"FAA and NTSB data via eFlight Registry (https://eflight.com)","connections":[{"group":"Applies to","items":[{"count":2,"name":"Pratt & Whitney PW4090","note":"","unit":"aircraft","url":"https://eflight.com/engines/pratt-whitney-pw4090#airworthiness"}],"relation":"applies to"},{"group":"System","items":[{"count":null,"name":"Engine","note":"","unit":"","url":"https://eflight.com/systems/engine"}],"relation":"about"},{"group":"Related orders","items":[{"count":null,"name":"Replaced by 2022-06-09","note":"","unit":"","url":"https://eflight.com/directives/2022-06-09"}],"relation":"related to"},{"group":"More","items":[{"count":null,"name":"Every FAA order","note":"","unit":"","url":"https://eflight.com/directives"},{"count":null,"name":"Every aircraft system","note":"","unit":"","url":"https://eflight.com/systems"}],"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":{"effective":"","faa_document":"https://drs.faa.gov/browse/excelExternalWindow/E4C5740884ADBC78862586860008E6E8.0001","id":"2021-05-51","kind":"Emergency AD","name":"Airworthiness directive 2021-05-51","published":"","subject":"Turbine Engine Compressor Section","system":"engine","type":"directive","url":"https://eflight.com/directives/2021-05-51"},"source":"FAA Civil Aviation Registry, FAA airport file, NTSB accident database; assembled by eFlight Registry"}