{"as_of":"2026-11-06","attribution":"FAA and NTSB data via eFlight Registry (https://eflight.com)","connections":[{"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":"1986-10-24","faa_document":"https://drs.faa.gov/browse/excelExternalWindow/170FABB363DF843A86256A4E0049CB72.0001","id":"86-21-01","kind":"AD","name":"Airworthiness directive 86-21-01","published":"","subject":"Main Rotor Head Sleeves","system":"rotorcraft","type":"directive","url":"https://eflight.com/directives/86-21-01"},"source":"FAA Civil Aviation Registry, FAA airport file, NTSB accident database; assembled by eFlight Registry"}