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Innovative Ultra Violet and Ozone Resistant Material for Hydraulic Clamp Cushions



OBJECTIVE: Develop an alternative material for hydraulic clamp cushions that is resistant to both ultra violet (UV) and ozone exposure and compatible with the relevant hydraulic fluids of the Navy. 

DESCRIPTION: The Navy uses cushioned clamps to fasten, support, and protect hydraulic tubes from loading and vibration. These clamps are comprised of a metallic band that utilizes a soft cushion material to reduce the loading and vibrational effects. There are several versions of these clamps, one of which is composed of an elastomeric, nitrile rubber. The nitrile clamp cushions sporadically crack shortly after installation on aircraft due to a combination of UV and ozone exposure. Any cracking on the clamp’s cushion that is visible by the un-aided eye as well as any major discoloration dictates a clamp failure, which results in replacement of the failed clamp. Because cushioned clamps can be used on hydraulic, fuel, and electrical applications, the cushion material can be exposed to fuel and petroleum-based hydraulic system fluids. At the part level, the replacement activity for these cushioned clamps equates to $640 per clamp for the CH-53K. Multiplying the cost to replace a clamp by the total number of clamps out in the fleet provides insight into how expensive the direct cost of replacing these clamps truly is. The indirect cost associated with a clamp failure is more important. Once a clamp fails, the hydraulic or fuel tube is no longer adequately supported, which could result in two immediate problems: the hydraulic tube might break or the hydraulic tube might chaff against another tube or structure. Either scenario creates a detrimental effect for the aircraft, further increasing cost and decreasing fleet readiness. The clamp cushion must meet the performance requirements as specified in MIL-DTL-85052/1C and MIL-DTL-85052B. 

PHASE I: Develop concepts for alternative materials for hydraulic clamp cushions that are resistant to both UV and ozone exposure and compatible with the respective hydraulic fluids used by the Navy. Demonstrate the feasibility of the developed cushion material concept to meet the Navy’s unique environmental requirements for hydraulic, fuel, and electrical clamp applications. The Phase I effort will include the development of prototype plans for the clamp cushion material for Phase II. 

PHASE II: Fully develop the prototype clamp cushion material to meet the Navy’s requirements and perform all required validation and certification testing in accordance with MIL-C-85052A. 

PHASE III: Transition the clamp cushion material to the Navy and other branches of the military for aviation and other applications. Development of this new material could benefit the private sector by enhancing clamps used in hydraulic systems such as in commercial aircraft. Successful technology development would also allow the material to be used for other applications in a vibrational environment where tubing needs to be fastened. 


1: MIL-DTL-85052B. Clamp, Loop, Cushion, General Specification For.

2:  MIL-DTL-85052/1C. Clamp, Loop, Tube- I7-7 PH Cres, 275F, Fuel And Petroleum Based Hydraulic Fluid Resistant.

3:  MIL-PRF-83282D. Hydraulic Fluid, Fire Resistant, Synthetic Hydrocarbon Base, Metric, NATO Code Number H-537.

4:  SAE AS5440A. Hydraulic Systems, Military Aircraft, Design and Installation, Requirements for.

KEYWORDS: Nitrile; Clamps; UV; Ozone; Resistant; Hydraulic 


Mark Healy 

(301) 757-2931 

James Rieder 

(301) 342-7994 

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