The RAAF's order of 75 Hornets comprised 57 single-seat "A" variant fighters and 18 two-seat "B" variant operational training aircraft. It was planned that each of the three fighter squadrons and the single operational conversion unit that were to operate the F/A-18 would be allocated 16 aircraft, of which 12 were expected to be operational at any time while the other four were undergoing maintenance. The remaining eleven Hornets were labelled the "half-life attrition buy" and would replace the aircraft that were expected to have been lost by 2000; as it happened, this greatly exceeded the RAAF's actual losses. Deliveries were planned to start in late 1984 and be completed in 1990. The total cost of the F/A-18 program, including the aircraft, spare parts, other equipment and modifications to the RAAF's fighter bases, was calculated as A$2.427 billion in August 1981, but was rapidly revised upwards due to the depreciation of the Australian dollar at this time.
The Australian Hornets were very similar to the standard US Navy variants, but incorporated a number of minor modifications. These included the addition of an Instrument Landing System/Very High Frequency Omnidirectional Range (ILS/VOR) system, a high-frequency radio, a different ejection seat harness and the deletion of all equipment used only to launch the aircraft from catapults. In addition, two of the Australian aircraft were fitted with flight-test instrumentation so that they could be used as part of trials.
F/A-18A and B variant deliveries
The Government sought to use the Mirage III replacement program as a means to increase the capabilities of Australia's manufacturing industry. Accordingly, it was decided to build the aircraft in Australia, though it was recognised that this would lead to higher costs than if the fighters were purchased directly from the United States. While the first two RAAF Hornets were built in the United States, the remainder were assembled at the Government Aircraft Factories plant at Avalon Airport in Victoria, and their engines were produced by the Commonwealth Aircraft Corporation at Fishermans Bend in Melbourne. Another twelve Australian companies were involved in other stages of the project. These firms were sub-contracted to McDonnell Douglas and the other major US companies that produced components for the F/A-18, and had to comply with the requirements of the FMS program. The Australian Government hoped that Singapore and New Zealand would purchase Australian-built Hornets, but this did not eventuate. The Canadian Government expressed interest in purchasing 25 Australian-built F/A-18As in 1988 in order to increase its force of these aircraft after they had ceased to be manufactured in the United States, but this did not lead to any sales.
The Australian Hornets began to roll off the production lines in 1984. The first two aircraft (serial numbers A21-101 and A21-102) were entirely built at McDonnell Douglas' factory in St. Louis, and were handed over to the RAAF on 29 October 1984. These aircraft remained in the United States until May 1985 for training and trials purposes. The next two Australian Hornets (A21-103 and A21-104) were also built at St. Louis, but were then disassembled and flown to Avalon in June 1984 on board a USAF Lockheed C-5 Galaxy. The aircraft were then reassembled, and A21-103 was rolled out at a ceremony attended by Prime Minister Bob Hawke and the Chief of the Air Staff, Air Marshal David Evans, on 16 November. However, the aircraft's initial test flight was delayed until 26 February 1985 by a demarcation dispute over which category of pilot was permitted to fly the aircraft.
In order to meet production targets, GAF was required to complete 1.5 Hornets per month. Production fell behind schedule during the first half of 1987, however, as a result of inefficiencies at the company's factory and industrial relations problems. GAF was able to accelerate production later in the year, though some components that were planned to be manufactured in Australia were purchased from companies in the United States instead. The final cost of the Hornet project was A$4.668 billion; after adjusting for the depreciation of the Australian dollar this was $186 million less than the initial estimate.
The RAAF began to accept Hornets into service in 1985. A21-103 was formally delivered on 4 May of that year. Two weeks later, A21-101 and 102 were flown from Naval Air Station Lemoore in California to RAAF Base Williamtown in New South Wales between 16 and 17 May 1985. This ferry flight was conducted as a non-stop journey, and USAF McDonnell Douglas KC-10 Extender tankers refuelled each of the Hornets 15 times as they crossed the Pacific. As of 2005 this remained the longest single flight to have been undertaken by F/A-18s. Despite the delays to production in 1987, the final Australian Hornet (A21-57) was delivered on schedule at a ceremony held in Canberra on 16 May 1990. The F/A-18As were allocated serial numbers A21-1 through to A21-57 and the F/A-18Bs were allocated A21-101 to A21-118.
A major capital works program was also undertaken to prepare RAAF bases for the Hornets. Over $150 million was spent upgrading the runways, hangars and maintenance facilities at RAAF Base Williamtown, which has been the main F/A-18 base throughout the aircraft's service. The pre-existing airfield at RAAF Base Tindal in the Northern Territory was also developed into a major air base between 1985 and 1988 at a cost of $215 million so that it could accommodate No. 75 Squadron. Until this time the squadron had been stationed at RAAF Base Darwin which, due to its location on Australia's north coast, was vulnerable to damage from cyclones and difficult to defend during wartime.