Balanced innovation

Temporary wiring like this during propeller balancing of C-130Js should soon be a thing of the past.

THE Defence Science and Technology Organisation’s exploration of the potential to use the C-130J on-board engine monitoring system for propeller balancing has attracted interest from the aircraft’s manufacturers and the US military.

The innovation should save operational costs for our Air Force and other countries that fly the C-130J.

The Air Force will present its findings to the next C-130 Joint Users Group (JUG) in June after final trials at RAAF Base Richmond this month. The recommendation is expected to be that future system software upgrades incorporate the balancing procedure, according to DSTO’s senior research scientist, Brian Rebbechi.

“Air Force engineers and maintainers from No. 37 Squadron and ALSPO [the Air Lift Systems Program Office] are leading the conceptual design of the new system through their involvement in the Aircraft Data Diagnostics System Working Group of the JUG,” Mr Rebbechi said. “The overall impact will be reduced maintenance hours and costs because neither the acquisition of supplementary hardware nor ground running will be required.”

Propeller balancing is a necessary part of operating turboprop aircraft and aims to reduce vibration throughout the airframe. Operators of the C-130H aircraft are accustomed to the time-consuming and laborious installation of temporary wiring and sensors to carry out the task.

“About 18 months ago, we questioned why this should be necessary in an aircraft equipped with on-board vibration monitoring and sensors and the most up-to-date digital engine monitoring system in the Air Force,” Mr Rebbechi said.
DSTO, ALSPO and 37SQN conducted trials using ground-running equipment that indicated the system could provide a much more efficient and cost-effective solution than the current practice as the aircraft monitoring system appeared to calculate all essential data needed for a balance.

DSTO was invited to make a presentation on the trials to a meeting of the JUG. Then Lockheed Martin invited the Australian team to the US to meet with their senior propulsion engineers. The engineers were unable to find valid reasons as to why the system should not work and became keen to support the inclusion of in-flight propeller balancing in future software upgrades.

The company agreed to support a proposal to progress trials to the flight-testing stage. The US Air Force, US Coast Guard and US Marine Corps were also enthusiastic about the proposal and, based on the results so far, are considering abandoning plans to install and additional on-board system.

Phase 1 flight tests were conducted under Air Lift Group direction at Richmond last December. Propeller assemblies were intentionally unbalanced to test and establish the balance factors.

“The flight tests demonstrated the validity of using the engine monitoring system. This success has demonstrated the Air Force’s ability to drive technical development of the aircraft,” Mr Rebbechi said.

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