Hydraulic systems in helicopters for the US Army Engineering Directorate



New type of non-shedding,vibration-adverse media was needed for hydraulic components

Bekipor® ST


The hydraulic systems in US Army Blackhawk and Apache helicopters were costing over $73M per year in repair and overhaul. And while maintenance was being performed, the helicopter fleet’s readiness was compromised. The solution was to replace the glass fiber filter material with Bekaert’s metal fiber media. Matthew Boenker from the US Army Engineering Directorate explains how the problem was identified, and the benefits of the Bekaert solution..

The challenge

“After intensive in-flight testing and measurement of a helicopter’s hydraulic filter, and then simulation of the results in a high-tech lab, the exact problem became apparent. The hydraulic filters were made of cellulose (paper) and glass fiber filter material. Intense flow changes and vibrations during flight were causing glass fibers and trapped contaminant to be shed into the hydraulic system. Here they were causing major damage to the downstream hydraulic components. It was clear that a new type of non-shedding, vibration-adverse media was needed.”

The solution

“Metal fiber media from Bekaert were qualified and tested, and the problem of shedding was not found. However, more testing in actual flight conditions was necessary. Consequently, the metal  fiber elements were placed on 60 helicopters where they endured 34,000 hours of intensive flight testing. The results were impressive. Contaminant levels were greatly reduced, and in some cases were as low as Class 0, which is laboratory-grade cleanliness. This has knock-on effects for other parts. For example, previously we had been changing out 285 hydraulic pumps every year. After installation of the new filters, this was reduced to 25 per year. We are delighted with the Bekaert metal fiber filter media. The reduction of contaminants in the system has prolonged the life of the hydraulic systems, reduced maintenance costs by 90%, and cut the size and cost of our spare parts inventory. Helicopter downtime has been significantly reduced, and in parallel fleet readiness time has dramatically increased.”

Bekipor ST hydraulic filter element


Read our whitepapers on metal fibers in hydraulic filtration