As early as 2012 the RAAF Hornet fleet flight activities (12-13000 hours per year) were estimated to exhaust the fleets' lifetime airframe limits (6000 hours) in 2020.[1] Keeping them in the air beyond this year was going to get more and more expensive and consume maintenance resources (and pilot training) that could otherwise be directed to the Super Hornets and F-35s.

Frankly I'm kind of glad someone took them off our hands before they became even more of a liability. We've got enough on our plate dealing with the F-35's corrosion issues (most of the fleet will be kept in moist salt air at Williamtown and be plugged into big dehumidifiers when not flying) and other things like its limited range.[2]

Which, now I put it that way, makes me wonder if maybe we should have kept a few Hornets.

[1] "43. The F/A-18A/B Hornet was designed for a safe life of 6000 airframe hours. At the current fleet flying rate of 13 000 hours per year, reducing to 12 000 from 2013–14, there is capacity on that basis for the Hornet fleet to continue flying until the end of 2020." https://www.anao.gov.au/work/performance-audit/management-au...

[2]https://www.aspistrategist.org.au/projecting-power-with-the-...