{"as_of":"2026-10-07","attribution":"FAA and NTSB data via eFlight Registry (https://eflight.com)","connections":[{"group":"Applies to","items":[{"count":477,"name":"Bell 47","note":"","unit":"registered","url":"https://eflight.com/models/bell/47#airworthiness"},{"count":14,"name":"Texas Helicopter Corp OH-13","note":"","unit":"registered","url":"https://eflight.com/models/texas-helicopter-corp/oh-13#airworthiness"}],"relation":"applies to"},{"group":"System","items":[{"count":null,"name":"Rotorcraft systems","note":"","unit":"","url":"https://eflight.com/systems/rotorcraft"}],"relation":"about"},{"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":"1986-01-08","faa_document":"https://drs.faa.gov/browse/excelExternalWindow/21FDB451D687ABB086256A4D0073C59C.0001","id":"85-15-04","kind":"AD","name":"Airworthiness directive 85-15-04","published":"","subject":"Tail Rotor Blade Yolk P/N 74-641-057-9","system":"rotorcraft","type":"directive","url":"https://eflight.com/directives/85-15-04"},"source":"FAA Civil Aviation Registry, FAA airport file, NTSB accident database; assembled by eFlight Registry"}