The Orroral Valley fire was sparked by the landing light of an MRH-90 Taipan helicopter in January.

It went on to destroy several homes as well as 80 per cent of the Namadgi National Park.

Defence revealed in January the helicopter was almost engulfed by the flames. No crew members were injured.

However they did not alert authorities to the blaze until the helicopter made it back to Canberra Airport - 45 minutes after the fire started.

Defence failed to explain the 45-minute delay in the passing on location data when contacted by The Canberra Times, only saying the safety of the crew was a priority.

The Greens peace spokesperson, Jordan Steele-John said residents of the Canberra region - especially those who lost their homes - deserved to know what happened.

"This was a tragedy that destroyed homes and 80 per cent of a treasured national park that is home to a number of threatened species," Senator Steele-John said.

"It is clear that Defence have tried to hide their involvement in this disaster and its now up to the Defence Minister to explain why, apologise to Canberrans and outline what actions she has taken to ensure that something like this never happens again."

A spokeswoman for Defence Minister Linda Reynolds failed to respond to a request for comment.

Around 8000 Defence Force personnel were involved in Operation Bushfire Assist last fire season, including more than 2500 reservists who were called in to assist.

They moved more than eight million litres of water; 73,000 litres of fuel; 13,000 tonnes of fodder; and 1200 tonnes of air cargo.

They also cleared 4850 kilometres of road, repaired 1280 kilometres of fencing, cleared 240 kilometres of fire breaks and evacuated 527 people.

As of June, the operation cost $66 million.

A bill that would make it easier for the Defence Force to be called out during natural disasters is currently before the Senate.

For faster access to the latest Canberra news, download The Canberra Times app for iOS and Android.