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Thursday, July 1, 2010

Perspectives: Corrosion Prevention

The Perspectives column, “Finding No Fault,” by Ken Anderson (Avionics, February 2010, page 38) was informative and factual regarding the high cost of No Fault Found (NFF) electronics within the aviation industry.

All electrical connectors are subject to corrosion; even gold-plated connectors are not immune. Corrosion in avionics connectors is invisible to the naked eye in the early stages and therefore easily overlooked. However, this invisible film is sufficient to render systems inoperative or create intermittent problems. Corrosion Preventative Compounds (CPC) have proven to be very successful in significantly reducing these problems and their related costs.

Anyone who has worked in avionics knows the routine for a quick fix by recycling the circuit breaker, resetting the connector or reseating the line replaceable unit (LRU). In reality, each one of these procedures will occasionally clean away just enough of the insulating corrosion to create a temporary path and complete the circuit. This may allow a few more flights, but the system will soon return as failed or intermittent.

With the introduction of CPCs in the late 1990s, we have seen a definite increase in Mean Time Between Removals (MTBR) and a decrease in NFF reports. Ground and flight-testing have been conducted on Mil-L-87177A CPC products to verify effectiveness on Fretting and chemical corrosion.

CPCs have been tested on avionics components, computers, enclosed switch boxes, card edge connectors, ground lugs, etc. Avionics systems included flight controls, navigation and communications. These tests involved more than one aircraft type and were conducted in different geographic locations. LRUs treated with Mil-L-87177A had a MTBR increase of more than 10 times.

The high failure rates of LRUs within the group of test aircraft made the benefits of using CPCs immediate and across-the-board, with significant decreases in NFF reports.

Mil-L-87177A is a compliant Corrosion Inhibitive Lubricant/CPC that protects electrical components, mechanical components and surfaces by coating them with a thin stable film that has a very low vapor pressure (PSI), a very low surface tension and a high dielectric constant. It is stable from -70 to +550 Fahrenheit, is non-flammable and environmentally friendly. It is a hydrophobic that evaporates relatively slowly and does not gum up. These properties make it ideally suited for all flight and ground environments with proven success in extending MTBR.

More information on CPCs and cost saving analysis can be found at the U.S. Department of Defense Corrosion Defense (CorrDefense) Web site, www.corrdefense.org.

Bob Dujon is Southeast regional sales representative with AeroSafe Products, Inc., of Marietta, Ga.

To contribute to the Avionics Magazine “Perspectives” industry opinion column, contact Bill Carey, editor in chief, at 301-354-1818 or bcarey@accessintel.com.

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