A firefighting pilot swam to the back of his helicopter before trying to kick his way out after crashing into a dam.
The pilot heard an unusual noise and told investigators the helicopter kicked, the Australian Transport Safety Bureau (ATSB) said in a preliminary report into the collision west of Brisbane published on Thursday.
The Bell204B aircraft was collecting water to fight a bushfire when it crashed at a private property at Tarome in the Scenic Rim on the afternoon of September 20.
Engine indications were normal and the 1200 litre bucket and short line were in an appropriate place, the pilot told the ATSB.
Concerned something was not right the pilot decided to dump the water and initiate a climb, ATSB director transport safety Kerri Hughes said on Thursday.
Within about 15 seconds the pilot heard a loud roaring sound as the helicopter pitched up then yawed before having a reduction in power.
The aircraft rolled left, hitting the water at low speed.
The pilot suffered minor injuries, while the helicopter was destroyed.
As the inverted helicopter started to fill with water and sink rapidly the pilot was unable to open a front door with the normal or emergency release handles.
"When the helicopter was almost fully submerged, the pilot swam to the rear of the cabin and tried to open the rear right door but could not open it either, making further attempts to get out by kicking the helicopter windows," Ms Hughes said.
"The pilot then moved to the rear left door and, utilising considerable force, was able to successfully open it."
Familiarity with the helicopter, an open area in the cabin where seats were removed and helicopter underwater escape training helped in the successful escape, he told investigators.
The investigation included interviewing the pilot and witnesses and preliminary examination of the wreckage.
A final report will be released, with the ATSB also to examine the pilot's training and records, maintenance documentation and key components of the helicopter.
"Should a critical safety issue be identified during the course of the investigation, the ATSB will immediately notify relevant parties so appropriate and timely safety action can be taken," Ms Hughes said.
