VH-ESZ has, until early last week, been operating out of Cairns Airport as "Rescue 510" and so is presumed that it has ferried to Archerfield for planned maintenance.
As posted below, on Sunday 17 April, fellow QGAir Rescue Agusta AW139 helicopter VH-ESH ferried North from Archerfield to Cairns via Rockhampton and Mackay Airports and immediately took up operations at Cairns Airport that day as "Rescue 510".
As we have reported previously, this 'rotational system' of airframes that QGAir utilises ensure the even distribution of flying hours on each of the their Rescue helicopters. This system avoids the need to have multiple helicopters offline for simultaneous scheduled maintenance.
Photo taken by John Lee ©