The CAA issued the safety message yesterday after The New Zealand Herald quoted sources as saying loose clothing was being investigated as a possible cause of the October 18 crash near Wanaka.
Pilot Nick Wallis and Department of Conservation rangers Paul Hondelink and Scott Theobald were killed in the crash.
It is believed the occupants of a trailing helicopter, belonging to another local firm who were leaving from Wanaka Airport on the same tahr cull operation, saw clothing being sucked out of the machine and wrapping around the tail rotor.
The CAA yesterday issued a safety warning titled ''loose items can be fatal''. It said analysis of helicopter occurrence data ''identified a number of accidents and incidents where loose items in the cabin have exited the helicopter and contacted the tail rotor''.
''In some cases this has resulted in a complete loss of control of the helicopter.''
The warning included a video link to Robinson Helicopter Company, which recently released a safety video concerning the dangers of loose items in and around helicopters.
Watch Robinson Helicopter video
It said pilots and crews needed to ensure all items in the cabin were securely stowed before take-off, even if operating with all doors fitted.
''Passengers must be briefed on the dangers of loose items in and around the vicinity of helicopters.''
It was not immediately clear if the safety message was linked to the Transport Accident Investigation Commission investigation into the Wanaka crash.
Investigators refused to comment when approached by the Herald, saying only that its inquiry ''continues in the evidence-gathering phase''.
Multiple sources told the Herald that clothing - either overalls or possibly a jacket - was seen flying out of a door and that it was being investigated as a possible contributing factor to its catastrophic failure.
