When Australia announced its purchase of the C-130J Hercules in December 1995, few could imagine the challenges that would be faced bringing the aircraft into service.
Previous C-130 variants had been incremental developments of earlier models, whereas the C-130J was the most significant development of the Hercules since the YC-130A prototype’s introduction in 1954.
Doctor Robyn Clay-Williams, a retired RAAF Wing Commander and test pilot, was part of the Australian project team that worked with Lockheed Martin to test the C-130J before it entered service.
“A test program that was originally supposed to take 12 months eventually took five years,” Doctor Clay-Williams said.
“We did the same flying as the Lockheed Martin test pilots - including the high risk work, such as stall testing, ground and flight control with engine(s) out, and airframe icing flights.”
Joining the Air Force in 1979, and completing her Electronic Engineering degree with RAAF Doctor Clay-Williams graduated as one of the RAAF’s first female pilots with Flight Lieutenant Deb Jeppesen (nee Hicks) in 1988.
After flying the CT-4/A and Macchi MB326H in training, Doctor Clay-Williams served a tour on the HS748 at RAAF Base East Sale with the School of Air Navigation, and then No 32 Squadron.
Her path to the C-130J test program began in 1993 when she completed the International Test Pilot School course in the United Kingdom, making her the RAAF’s first female test pilot.
On that course, she performed tests on a range of aircraft and different areas of their operation, flying helicopters, ultralights, small and large transports, and fast jets.
Following this, she was posted into the Aircraft Research and Development Unit (ARDU) at RAAF Base Edinburgh, and flew the PC-9/A, C-47B Dakota, Nomad, and C-130E Hercules.
Around this time, the RAAF was embarking on a replacement project for the 12 C-130E Hercules flown by No. 37 Squadron.
Introduced to service in 1966, the C-130E’s age would require either an extensive refurbishment or replacement with a new transport.
Doctor Clay-Williams’ experience in ARDU led her to be posted to the C-130J Project Team when the aircraft was selected as a C-130E replacement.
“I reviewed the aircraft specification and contract documentation for the C-130J project whilst still at ARDU,” Doctor Clay-Williams said.
“When the RAAF was invited by Lockheed Martin to provide a test pilot for the J-model program, I was the obvious choice.”
A RAAF Project Team was dispatched to the United States to work alongside Lockheed Martin in November 1995.
They would be embedded with the C-130J test and evaluation team at Dobbins Air Base in Marietta, Georgia.
Lockheed Martin completed the first flight of a C-130J in April 1996, and Doctor Clay-Williams flew the maiden flight of the RAAF’s first ‘J-model’ - A97-440 – on 16 February 1997.
Also on board that flight was Flight Lieutenant (now Group Captain) James Blagg as the flight test engineer, along with four members of Lockheed Martin’s test team.
The flight lasted for five hours and 34 minutes, and included safety of flight evaluations, system checks, and a formation flight with a B-25 Mitchell used to collect air-to-air imagery of the Hercules.
Lockheed Martin anticipated the new Hercules model would have a relatively straightforward test and evaluation program.
In reality, the C-130J brought fundamental changes to how the Hercules would be operated by its crew, as well as how it would perform in different conditions.
This led the RAAF’s first C-130J to be used by Lockheed Martin for the test and evaluation program.
Earlier Hercules variants were powered by four Allison T56 turboprops, with each engine driving a three or four-blade propeller.
The C-130J replaced these with four Rolls Royce AE2100D turboprops, each driving a six-blade ‘scimitar’ propeller.
The new engine delivered greater power and efficiency, making the C-130J faster and longer ranged than previous variants, but also bringing fresh problems when the aircraft stalled.
“The combination of a new engine prop changed airflow over the airframe and tail,” Doctor Clay-Williams said.
“This completely changed flying qualities and performance, so a full test program was required.”
“The first time we tested stall, the wing unexpectedly dropped 110 degrees to almost inverted.”
To fix this, Lockheed Martin installed an automatic ‘stick pusher’ for the pilot’s control column, which would dip the aircraft’s nose to prevent it entering stall conditions.
The flight test program encompassed both the regular C-130J variant and the C-130J-30 – which was being acquired by the RAAF – that featured a stretched fuselage that could fit more cargo.
On the longer aircraft, test pilots found that ‘sideslipping’ by more than 10-15 degrees could result in a lateral departure from control.
Another new introduction to the C-130J was a Heads-Up Display (HUD) for the pilot that presented essential flight information.
The HUD could also be used to indicate when the aircraft was entering the edge of its flight envelope, but the device’s ergonomics also presented design challenges.
“When testing new HUD, I found that the seat was only set up for 5th-95th percentile of males, eliminating me plus more than half of the women flying C-130s in the United States Air Force,” Doctor Clay-Williams said.
Making the HUD suitable for all pilots required design changes to the seat, rudder pedals, and control yoke.
“The control yoke change in turn led to increased aileron control forces and changes to control harmonisation, and that required more testing,” Doctor Clay-Williams said.
“The new throttle quadrant would get hung up coming back over the gate on landing with any side force applied – such as when it was used by a smaller pilot – and took ten full redesigns over 12 months or so before we got it right.”
Being designed in the 1990s, the C-130J capitalised on advances in computing technology that allowed avionics to perform many functions previously managed by a human crew.
“Software testing was complex and laborious, and what seemed like a minor change would sometimes turn out to be critical to safe flight” Doctor Clay-Williams said.
In her last 12 months with the test program in Atlanta, Doctor Clay-Williams was promoted to Wing Commander and also made officer-in-charge of the US-based RAAF team.
The first C-130J for the RAAF was delivered to Australia in September 1999, but the testing in Atlanta continued as further fixes were applied.
“In my last six to eight months there, I test flew and accepted type as per contract, then test flew and signed for each of the 12 aircraft.”
After returning to Australia in 2000, Doctor Clay-Williams remained with the C-130J Project Office as it completed its work on the aircraft’s introduction to service.
She then served as the Officer Commanding No. 85 Wing before leaving the Air Force in 2003, completing a Doctorate and now working as a Senior Research Fellow with Macquarie University.
Since then, RAAF test pilots and flight test engineers have continued to develop the C-130J as changes have been introduced.
These include block upgrades and the installation of systems such as a Ka-Band Satellite Communications Antenna – a large hump on the aircraft fuselage.
Even two decades on from its acquisition, the C-130J illustrated some of the challenges that can face Defence when introducing a new system.
“There were three main lessons from the C-130J program – the first two in regard to software-driven aircraft,” Doctor Clay-Williams said.
“The first was that it can take three to five times as long as a manufacturer estimates to deliver updates, which needs to be factored into acquisition times.”
“The second was that software maintenance and upgrades will be the most expensive part of the acquisition, whether it seems that way initially or not.”
The third lesson is the importance of contract specification for new systems.
“You need to develop and contract for an operational/role specification for the aircraft, not just a technical specification,” Doctor Clay-Williams said.
“We managed to incorporate operational requirements after the C-130J contract signature because we had the weight and alignment of all three lead customers – Australia, the United Kingdom, and the United States.
“If the C-130J was delivered on what we initially contracted for, the aircraft would have only ever been able to fly strategic, peacetime missions into sealed airfields.”