Unlocking the mind of Hercules
News Item
- Date:
- 1 May, 2006
DSTO research has shown that the "brain" of the Hercules C-130J aircraft was not being used to its full potential.
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- Unlocking the mind of Hercules
According to DSTO researcher Brian Rebbechi, “The modern Hercules C-130J, acquired by the RAAF in 1999, is a software-driven aircraft with a mission computer, a central ‘brain’ that controls and monitors every function of the aircraft from checking if the rear door is closed through to keeping tabs on whether the engines are operating correctly.”
“We found an advanced engine monitoring capability that was active but wasn’t being used,” he says, “and to access this required no modification or change to aircraft hardware or software – only a tool to extract and decode data from a data bank recorded during every flight.”
The first application of this potential has been to access a latent on-board propeller balance capability.
Current procedure for all C-130J users is to temporarily install vibration sensors and wiring to each power plant, tow the aircraft to an engine run-up area, carry out vibration checks and balance if required, then after completion, return the aircraft to the flight line, remove temporary wiring, and return to service. This process takes around a full day, requiring two shifts with at least four people per shift.
Towards mission computer assisted propeller balancing
DSTO’s research into propeller balancing began in 2003 when Rebbechi inquired into why the existing C-130J on-board vibration monitoring system wasn’t being used for this purpose. There seemed to be no convincing reason. The RAAF offered him support for limited ground testing of the system. He took the results of this work to Sydney in April 2003 to present to the C-130J Joint Users Group.
There he was given a keen but cautious response, with Lockheed Martin Aeronautics (LM Aero) inviting him to visit its plant in Marietta, Georgia in the United States, to further discuss the proposal with its propulsion people. During this visit, Rebbechi established the basic balance principles and algorithms involved, and explained the success of earlier testing on RAAF aircraft.
The appraisal by LM Aero was that ‘it would probably work, but needed flight testing’.
The RAAF and DSTO then proceeded to a flight test program in December 2003. With the participation of a US Navy test pilot from Pax River Naval Air Station, and with LM Aero representatives looking on, a ten-hour test program was undertaken and proved the validity of the methodology. A final trial was carried out in May 2004 on two operational aircraft, confirming in-service effectiveness.
A major advance in C-130J capability
The trials showed that all of the required balance data could be derived from a single ‘event marker’ button push on the aircraft, and the data could be interrogated with a solution computed just a few minutes after landing. The correction process involved a simple procedure of making the appropriate weight changes at the propeller hub, with no ground running necessary.
These developments allow for a dramatic improvement in capability and availability since the procedure can be undertaken with no disruption to aircraft operations. During the May 2004 demonstration, an aircraft used for the trial balance procedure completed two regular operational sorties that day, with the weight changes made during aircraft turnaround.
This new approach to propeller balancing is far superior to previous methods that require a full day when the aircraft is not available for operational use. The acquisition of a balance solution in-flight will also mean lower vibration levels, and aircraft balance only undertaken as and when necessary.
Certifying HUMS for engine operations
In a parallel activity, another DSTO researcher Graham Forsyth was tasked by the Director General Technical Airworthiness - Australian Defence Force (DGTA - ADF) to carry out certification of the Health and Usage Monitoring System (HUMS) component of the engine monitoring system, to validate its accuracy and for certification purposes.
Forsyth’s work uncovered many other features of this system, which he found could be used to not only record usage – its nominal function – but also record what are known as trend engine parameters that enable forecasting of engine hot section usage rates and remaining engine life.
Both the propeller balancing and engine monitoring activities DSTO has investigated are being merged into an enhanced ground station engine monitoring and trending system, of which the propeller balance capability will be the first component to see routine service early in 2006.
If you're interested in more articles about DSTO research, click on the link to our Australian Defence Science magazine, under Related Pages.
The Defence Science and Technology Organisation (DSTO) is part of Australia's Department of Defence. DSTO's role is to ensure the expert, impartial and innovative application of science and technology to the defence of Australia and its national interests.