The pilot of a helicopter that crashed in the Whitsundays last month saw a warning light come on and felt a thud before the fatal crash.
Two American tourists died when the chopper crashed into the water while trying to land on a pontoon at Hardy Reef on March 21.
The Australian Transport Safety Bureau released its preliminary report into the cause of the incident on Wednesday.
It found the pilot fought but failed to regain control of the chopper, which veered sharply to the left after the warning and the thud was heard.
He and two other passengers exited the chopper but Peter Hensel, 79, and his wife Sue, 65, could not get out.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
The pilot and a passenger then pulled the couple from the wreckage.
Staff from a nearby pontoon administered CPR until emergency services arrived but they could not be saved.
The pair had been on their dream honeymoon after getting married last December.
The other passengers, believed to be Sue's daughter and her partner, escaped with minor injuries.
Queensland police have since located the wreckage and the ATSB may recover it for further investigation.
The final ATSB report is due in early 2019.
