A pilot was able to successfully escape their sinking aerial firebombing helicopter with just minor injuries after punching out a rear window and swimming to safety, the ATSB has found.
The Garlick Helicopters UH-1H, registered VH-ONZ, was being used to aid Australia’s Black Summer bushfire season on the NSW south coast, when it experienced a critical engine failure 100 feet above water.
According to the safety bureau, the UH-1H helicopter was collecting water from the Ben Boyd Reservoir to assist with bush-fire operations near Eden on 9 January 2020 when it suffered an engine failure and descended into the water.
Prior to the descent, the helicopter was hovering 100 feet above the reservoir when the pilot heard a grinding noise, ahead of the aircraft experiencing a total loss of engine power.
On impact with the water, the helicopter’s chin-bubbles fragmented, and the helicopter rolled inverted, filled with water, and sank, the ATSB report states.
The pilot was unable to open the pilot, co-pilot, nor sliding cabin doors, causing them to finally punch out the right sliding door rear window, and escape the sinking helicopter.
The pilot then inflated their lifejacket and swam to shore.
Before the escape, the pilot said they were able to locate a pocket of air in the cabin, allowing them to take an additional few breaths of air.
The pilot later told the ATSB that their previous helicopter underwater escape training (HUET) was pivotal to their safe escape from the sinking aircraft that day.
The pilot went so far as to say that they “would have been dead without HUET”, the ATSB noted.
A teardown inspection of the helicopter later found that the engine failure was caused by inadequate lubrication to two main bearings in the front section of the engine.
This resulted in contact between the power and compressor shafts, disconnection of rotational drive to the fuel pump and fuel control, and subsequent fuel starvation, according to the ATSB.
However, the exact cause of the restriction of oil flow to the main bearings in the front section of the engine was not able to be established.
“Research into helicopter overwater accident survival consistently reports drowning as the leading cause of fatalities, due to the inability of the occupant to hold their breath long enough to escape,” said ATSB chief commissioner Angus Mitchell.
“In this accident, the pilot found an air pocket in the cabin, which enabled the escape time to extend beyond the initial breath-hold time. While it could not be determined if the pilot would have drowned without the air pocket, it would have increased that likelihood.
“Although the pilot was able to successfully escape from underwater after finding the air pocket, an emergency breathing system would have reduced the risk of drowning.”
The ATSB noted that while the pilot had conducted a number of HUET courses, they had not completed part of the emergency breathing system (EBS) training, due to the operator not utilising EBS equipment in their aircraft.
While this is currently not a requirement, the ATSB highlighted the importance of both EBS and HUET in avoiding possible fatalities.
“Helicopter underwater escape training – or HUET – provides a learning environment for the essential skills of maintaining orientation, location, and operation of exits,” Mitchell said.
“However, extended breath-hold may be necessary for problem-solving and physical effort during an underwater escape, such as dealing with snagging hazards, obstructions, or inoperative exits that require an alternative escape route, as in this accident.
“In these scenarios an EBS can afford the pilot sufficient time to perform the escape actions without an air pocket and therefore reduce the risk of drowning.”
Following the accident, the pilot acquired a compressed air EBS and intends to conduct the EBS elements of future HUET courses.
“The operator reported they have started investigating how to implement EBS company-wide, and how to attach the units to their pilots without limiting their movement when conducting long-line operations,” Mitchell said.