TECHNOLOGY AREA(S): Materials/Processes

ACQUISITION PROGRAM: PMA 265 F/A-18 Hornet/Super Hornet

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 DUAL USE APPLICATIONS: 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.

REFERENCES:

1. MIL-DTL-85052B. Clamp, Loop, Cushion, General Specification For. http://everyspec.com/MIL-SPECS/MIL-SPECS-MIL-DTL/MIL-DTL-85052B_5309/

2. MIL-DTL-85052/1C. Clamp, Loop, Tube- I7-7 PH Cres, 275F, Fuel And Petroleum Based Hydraulic Fluid Resistant.� http://everyspec.com/MIL-SPECS/MIL-SPECS-MIL-DTL/MIL-DTL-85052-1C_14037/

3. MIL-PRF-83282D. Hydraulic Fluid, Fire Resistant, Synthetic Hydrocarbon Base, Metric, NATO Code Number H-537. http://everyspec.com/MIL-PRF/MIL-PRF-080000-99999/MIL-PRF-83282D_7238/

4. SAE AS5440A.� Hydraulic Systems, Military Aircraft, Design and Installation, Requirements for. http://standards.sae.org/as5440a/

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