Two people have escaped serious injury after a helicopter crashed while doing circuits near a regional Victorian airport.

The Robinson R44 helicopter was doing circuits — taking off and landing — when something went wrong around 10:00am, Lethbridge Airport owner Gary Baum said.

Mr Baum said he found the helicopter on its side, with one man lying on the ground and another walking nearby.

They were both talking, he said.

The helicopter crashed about 10:00am. ( ABC News )

"[There's] severe damage underneath the helicopter and the rotor blades have actually hit and broken the tail off and exploded but the cabin has stayed all together."

"The debris of the whole aircraft is scattered over a 50-metre radius."

Mr Baum said the tail of the chopper was found some 25 metres from the cabin.

Police said the helicopter was flying low and appeared to have "got out of straight-level flight" when it crashed near the airfield, about 80 kilometres south-west of Melbourne.

Acting Senior Sergeant Peter Anderson said it was too early to tell if the crash was the result of pilot error or a mechanical fault.

"The pilot's got into some difficulty and the helicopter's hit the ground reasonably hard. It's bounced a short distance and come to rest on its side," he said.

The crash destroyed everything but the cabin the two men were in. ( ABC News: James Oaten )

Mr Baum said the helicopter was severely damaged and fuel had leaked.

"The rotors, the two blades of the helicopter are severely twisted around themselves," he said.

"There is no back to the helicopter. It's dotted all over the place and it's just the cabin that's stayed nicely intact.

"I would not liked to have been in the actual aircraft, even though the cabin is complete, because the aircraft is torn apart."

Two Ballarat men in their mid-30s suffered minor injuries.

One was flown to the Royal Melbourne Hospital with back injuries. He was in a stable condition.

The airfield is about 80km south-west of Melbourne. ( ABC News )

The other man was taken to Ballarat Hospital.

Acting Sergeant Anderson said the two men were lucky to escape with their lives.

"It's not often people walk away from a helicopter crash," he said.

Mr Baum said there had been a fatality at the Lethbridge Airport before.

"It's a terrible thing. It's every airport owner or operator's worry," he said.

"It doesn't take much to kill someone so it was a very good outcome to see these two were both talking to me when I went down there."

The Robinson R44 is the most registered helicopter in Australia and seats four people.

It is commonly used for flight training, private use and by pastoralists.

Debris from the crash was scattered across the area. ( ABC News )

In the past decade, there have been 41 fatal helicopter crashes in Australia, 10 of which were in R44s.

Benjamin Morgan from the Aircraft Owners and Pilots Association of Australia said the R44 had a good track record considering how often it was flown.

"It's flown by thousands of pilots globally," he said.

"It has a fantastic safety record when you look at the number of thousands of flight hours that are flown by these types [of helicopters] … so no, we do not consider it to be a concern."

Lethbridge Airport is home to multiple businesses, such as those running lessons and joy flights, and is the base for the Geelong Sports Aviators club.

The CFA, Air Ambulance and police use the airport as a refuelling station.

Police said the Civil Aviation Safety Authority (CASA) and the Australian Transport Safety Board had been notified of the crash.