The US Defense Security Cooperation Agency (DSCA) has granted approval for a $1.5 billion sustainment package related to Australia’s 24 Boeing F/A-18F Super Hornets and future fleet of 12 EA-18G Growlers.

The package includes software and hardware upgrades, engineering change proposals, spare parts, and a range of other equipment and services related to the aircraft, says the DSCA in a statement.

Boeing is the prime contractor for the deal, which has yet to be approved by Canberra.

The Royal Australian Air Force operates 24 Super Hornets, and its EA-18Gs are in production.

“The proposed sale of follow-on sustainment support and services will enable the Royal Australian Air Force to ensure the reliability and performance of its F/A-18 fleet,” says the DSCA. “The follow-on support will allow Australia to maintain aircraft availability/operational rates, and enhance interoperability with the U.S. and other nations.”