A report into a light plane crash that killed five men at a Melbourne shopping centre will be delayed because investigators had to spend so much time at the crash site.
Four Americans on a golfing holiday and a Victorian pilot were killed when their small plane crashed into a nearby shopping centre soon after take-off from Essendon Airport in February.
The Australian Transport Safety Bureau has been investigating, with a preliminary report originally due on March 21.
But the report has been delayed by a week.
"The preliminary report release will be slightly delayed due to the extensive on-site activities required for this investigation," an ATSB investigation update reads.
The United States National Transportation Safety Board and Federal Aviation Administration have also been involved in the investigation.
Help from the US agencies, along with the engine manufacturer, has allowed the ATSB to disassemble and examine both of the Beechcraft Super King Air plane's engines.
Investigators have collected a large amount of evidence from the crash site, along with CCTV footage and witness statements.
The plane hit the back of the DFO in Essendon during morning peak hour traffic, exploding in a large fireball just metres from the Tullamarine freeway.
The four US citizens were retirees from Texas who were on the "trip of a lifetime" were flying to King Island to play golf.
Their wives were also travelling with them but were not on the plane.
The pilot Max Quartermain, had been flying for 38 years.
