General Electric Aviation Systems (GEAS) this fall could begin flight trials of a novel wire bundle health monitoring system on a US Navy SH-60 Sea Hawk helicopter, a technology that could decrease not-mission-capable rates and depot-level repair costs by estimating when and where wire insulation breaks will occur.
The monitoring system, developed by experts at GE's Global Research Centre in New York, is part of a broader push by the company to expand traditional health and usage monitoring (HUMS) packages into prognostics health management platforms for complete aircraft and entire fleets. From a whole-aircraft detection standpoint, hot research areas aside from getting advance notice of wire insulation breakdown include developing sensors that can alert operators of corrosion and virtual detectors that can estimate wear and tear of high-stress airframe locations.
GEAS's HUMS contingent, formerly Smiths Aerospace, has been building certified HUMS systems since 1991, starting with oil and gas industry helicopters in the North Sea. Since acquiring Smiths in May 2007, GE's strategy has evolved from being a piece-part HUMS provider to a total platform integrator, a move that takes advantage of GEAS broad product spectrum.
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Traditional HUMS tap into aircraft data systems to highlight anomalous performance of a component -- typically engines, power train, gearboxes and bearings -- compared to fleet or aircraft norms. Future HUMS concepts centre around prognostics and health management (PHM) systems that will rely not only on new sensors for issues like wire health, but on mathematical models that will transform readily available aircraft performance information into data of particular interest.
Converting Data
For example, airspeed, attitude and other readily available flight performance data might be converted by test-verified maths models into structural stresses and strains on a particular joint, knowledge that will be critical to understanding theremaining life of the structure, particularly after an event like a hard landing.
Many of the new sensors needed to evaluate an entire aircraft will be non-traditional. Under a new contract with the US Army, GE will create an integrated sensor to monitor corrosion in metal structures, a problem difficult if not impossible to discern by visual inspections.
GE says corrosion is an integrated health monitoring "blind spot" at the moment. As part of the two-year effort, the company plans to test several varieties of off-the-shelf corrosion sensors during accelerated life tests in the laboratory.
Environmental corrosion sensors use a sacrificial material that emulates the corrosion in the material to which it is attached. One downside of adding more sensors, however, is the weight and complexity of the wiring needed to connect the equipment to the aircraft data bus.
Virtual sensors, which generate health data based on aircraft performance data and test-verified mathematical models, are emerging as a reliable tool for aircraft structures and even engines. Smiths and BAE Systems tested the robustness of its virtual modelling techniques by computing the stress and strain at four locations for a particular aircraft type using 15 years of actual data. The results were impressive: Test points in wings and tail structures matched to well within the tolerance of the strain gauges used to measure the loads on the aircraft.
Source: Flight International