I just read Capt. Edward R. Hanson Jr.’s Product Focus article on connectors in the July issue (page 45) and would like to offer some observations.
I view connectors as a potential weak link in a wire chain. Many connectors are made of one metal and are mated to sockets containing a dissimilar metal. This sets up an environment for galvanic corrosion to take place. Putting these connectors into an aircraft and subjecting them to humidity and vibration as well as changes in pressure and temperature often results in fretting corrosion, which leads to malfunctions and premature failure.
Spotting corrosion on electrical connectors is analogous to assessing an insect infestation; once you see your first roach, you know you have a problem. If the avionics technician can see the corrosion in a connector, it’s too late.
Electronic components have a very low tolerance for corrosion. It doesn’t take much to cause malfunctions and failure. And breaking down and re-racking connector mates does little or nothing to correct the problem.
One very effective solution would be to make sure that the connector mates are made of similar metals, thus eliminating the potential for galvanic action. Another important practice would be the use of corrosion preventation compounds on the connector’s male and female mates.
A corrosion preventation compound is a high-dielectric coating that can be sprayed, poured or brushed onto the connector’s pins and sockets to displace moisture. This can protect against general corrosion and set up a microscopic cushion that protects the pins from attacking the socket walls when vibrating, thus reducing the potential for fretting corrosion. A top-quality corrosion preventation compound will remain flexible in a wide range of temperatures. It will not affect conductivity, and it will be safe on plastics and impervious to water and salt fog.
The use of connectors made with similar metals and the treatment of those connectors with quality corrosion preventation compounds can extend their usable life span and greatly reduce replacement costs, maintenance service hours and downtime.
Lewis M. Krosner
BAE the Veteran HUD Maker
In reference to James Ramsey’s story, "Weathering Fog and Darkness" (June 2001, page 32), we feel it is important to correct some information pertaining to our company and its capability in enhanced vision systems.
CMC Electronics is a new name for a company that will be 100 years old in 2002. The company was acquired by ONCAP (a subsidiary of ONEX Corp.) in April 2001 and renamed CMC Electronics. We should point out that the company was known as Canadian Marconi from 1925 onward, and BAE Systems Canada as a result of the merger of Marconi and British Aerospace in 1999.
The name changes certainly have been difficult to keep up with. However, Avionics Magazine readers should be informed that CMC Electronics is taking a modular development approach leading to fully integrated enhanced vision systems for aircraft equipped with head-up displays in the general aviation, military and air transport markets.
CMC Electronics and its U.S. subsidiary, CMC Electronics Cincinnati, have developed a small infrared sensor that, when installed under the aircaft’s radome, can detect subtle thermal gradients of the terrain ahead. CMC Electronics has designated the system the Infrared Enhanced Vision System (IR-EVS), representing the first stage in its modular development architecture. The first module will be followed by the second module, the CMC Electronics Millimeter Wave Imaging Radar (MWIR). Both systems will provide the ultimate safety in head-up situational awareness.
CMC Electronics will offer its Enhanced Vision Systems (both IR and MWIR) to all aircraft OEMs and operators for installation and fusion with head-up display systems. Flight trials for the IR-EVS are under way this summer, with MWIR flight trials scheduled to follow within 24 to 36 months.
CMC is not a supplier of head-up display systems or a world leader in the HUD market, as is described in the article. That distinction is held by BAE Systems.
Public Relations Manager
CMC Electronics Inc.
ATN Long Standardized
In your article, "The Fruits of FANS" (June, 2001, page 31), you state "Free Flight will use the Aeronautical Telecommunications (sic) Network (ATN), which is still to be internationally standardized." It may be of interest to note that the ATN standard was completed, approved by ICAO, and published several years ago.
Steve Van Trees
Avionics Systems Branch
Aircraft Certification Service
Mr. VanTrees is quite correct, and I apologize for appearing to ignore the extensive work that he and his ICAO colleagues have put into creating the ATN standards. Unfortunately, in trying to shoehorn a mention of the ATN into my FANS story, I inadvertently used the phrase "internationally standardized," instead of "internationally implemented by the airlines."
Telecommunications or Telecommunication? FAA prefers an "s" on the end of the word (see the NAS Architecture Plan), which I used, while ICAO discards the "s." Alas, internationally standardizing the ATN would have been a cakewalk compared to doing the same for the English language.–Brian Evans, author.