Concerns were flagged about a helmet used by MRH-90 Taipan pilots the night of a fatal crash after a test found a software upgrade posed an "unacceptable" risk, an inquiry has been told.
Captain Danniel Lyon, Lieutenant Maxwell Nugent, Warrant Officer Class Two Joseph Laycock and Corporal Alexander Naggs were killed when their chopper crashed off the north Queensland coast in July 2023 during Exercise Talisman Sabre.
The disaster led to the early retirement of the Taipans last year, their service already tarnished with fleet-wide groundings and serious incidents.
Hearings for the inquiry into the crash resumed on Monday.
Captain Andrew Balaam, a MRH-90 pilot posted to the School of Army Aviation, said a test of the latest software upgrade V5.10 for the TopOwl helmet worn by the pilots found an "unacceptable" risk.
He said the report deeming the upgrade "unacceptable" appeared to be "a bit of an outlier" as it had passed tests with the original equipment manufacturer and had been used by European militaries.
"I was gonna have to fly that thing for real at night over water in a degraded visual environment, I was happy to do that," he said.
"As indeed were the other 11 pilots ... we were not turkeys waiting for Christmas, we were going to have to use it.
"So I was happy to use it."
He was responding to a question about allegations aired during a 60 Minutes investigation the Australian Defence Force ignored warnings in 2020 about the safety of the upgrade, which could lead to deaths.
"I was aware that a previous test ... had been conducted where they had stated that version 5.10 was unacceptable," Captain Balaam told the inquiry.
"That was their conclusion."
He said he understood how the evaluation would have reached that view looking at it in isolation.
"If you took a slightly broader view and looked at what 5.10 was replacing and the advantages that it brought, on a balance of risk, it was probably wise to proceed, because the issues that it was resolving were equally as challenging," Captain Balaam said.
Asked if the pros outweighed the cons, he replied "absolutely".
Major Michael Perkins, who was posted as a senior flying instructor to the army's 5th Aviation Regiment, disputed the allegations raised in the 60 Minutes report as "factually incorrect".
"I disagreed with the sentiment," he said.
Major Perkins added Defence should look at the burden of the airworthiness delegations held by one person in the army, which was considerably greater than those in the navy and air force because of size.
The Taipans are set to be replaced with Black Hawks imported from the United States.
The inquiry continues.
