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Aircraft Carrier Elevator Wire Ropes Service Life Extended

Navy News Service

Story Number: NNS120809-19
8/9/2012

By Joseph Battista, Naval Surface Warfare Center Carderock Division, Philadelphia Support Branch

PHILADELPHIA (NNS) -- Naval Sea Systems Command Engineering Directorate (NAVSEA05) has recently extended the service life for wire ropes associated with aircraft carrier elevators (ACE) for all Enterprise-class, Nimitz-class and Gerald R. Ford-class aircraft carriers.

NAVSEA05 partnered with engineers from Aircraft, Vehicle, Ship and Material Handling Branch at Naval Surface Warfare Center Carderock Division - Ship Systems Engineering Station (NSWCCD-SSES) to test ACE wire ropes from USS Theodore Roosevelt (CVN 71).

As a result, NAVSEA05 approved the service life extension for wire ropes with corrosion protection from nine to 12 years as well as wire ropes without corrosion from eight to 10 years.

"This extension also applies to LHD 1 class and future LHA 6 (amphibious assault) class ships," said Christopher Petitpren, the project lead from NSWCCD-SSES. "Each amphibious assault ship has two ACEs, and the replacement cost is significant."

ACEs are used for an array of shipboard operations, including moving heavy ammunition and cargo from inside a ship to the flight deck. By extending the service life of the wire ropes, the Navy would not need to replace them as often, resulting in cost savings for several ships over a 24-year remaining service life.

Testing of the ACE wire ropes from CVN 71 included destructive pull testing of the platform hitch point connection section. The average breaking strength of the eight rope samples was approximately 255,000 pounds, which is above the current minimum breaking strength requirement for new wire rope of 250,000 pounds. Engineers also did a visual inspection, which showed much less corrosion of the sections with additional corrosion protection at the platform hitch point connection area, allowing a longer service life for those ropes.

In addition, fatigue testing, done in 2009, verified long-term wear and bending fatigue would not be a limiting factor for extending the service life. The tests showed the wire ropes held a residual breaking strength above 267,000 pounds after 120,000 bending cycles, which is far above the number an ACE wire rope would reach during its life-cycle. Through innovative research and development (R&D), NSWCCD-SSES and NAVSEA05 identified a cost saving measure that has fleet-wide implications in reducing Total Ownership Cost.

The Ship Systems Engineering Station, Philadelphia is a major component of NSWCCD. It is the Navy's principal Test and Evaluation Station and In-Service Engineering Agent for all hull, mechanical and electrical ship systems and equipment and has the capability to test and engineer the full range of shipboard systems and equipment from full-scale propulsion systems to digital controls and electric power systems. NSWCCD, headquartered in West Bethesda, Md., is a Naval Sea Systems Command field activity comprised of approximately 3,600 scientists, engineers, technicians and support personnel located across the United States.




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