AD/HILLER 12/6 - Superseded by AD/HILLER 12/11 - CANCELLED

What this is

This document formally cancels a 46-year-old aviation safety rule about Hiller UH-12 helicopters.

The backstory

• The original safety directive (AD/HILLER 12/6) was issued in 1963 to mandate specific maintenance or inspections for these helicopters
• It was replaced by a newer directive (AD/HILLER 12/11) in 1987
• That replacement was itself cancelled in 1987, leaving the original 1963 directive technically "superseded" but not formally "cancelled" on the books

What this document does It tidies up the regulatory records by formally cancelling the 1963 directive, effective 27 August 2009.

Who cares? Owners and operators of Hiller UH-12 helicopters. In practice, this change has no operational impact — the 1963 rules haven't applied for decades. This is purely administrative housekeeping to keep the aviation safety register accurate and prevent confusion.