This is a common question for aerospace engineers who are working with the Electrical Wiring Interconnect System (EWIS) as well as aerospace Maintenance Repair and Operations (MRO) professionals.
Basically, if you have an EWIS component that needs to be tested, you can either test it yourself or contract with an aerospace wire testing organization. However, the cost of the equipment for an aerospace wire testing laboratory can be prohibitively expensive since the equipment necessary to run the tests could include humidity chambers, high voltage equipment, generators, scientific ovens, ultra-low temperature freezers, custom-made scrape abrasion instruments, and much more.
Even if equipment cost was not a concern, you would have to find qualified engineers. Running an aerospace wire testing facility can be expensive to set up and difficult to staff.
Criteria for Selecting an Aerospace Wire Test Laboratory
If you choose to contract with an aerospace wire testing organization, you would likely start with a search of facilities that can test wires or cables. However, some testing organizations are “one-size-fits-all.” In other words, they may test electrical equipment for aerospace, rail, and other transportation devices.
As a general rule, it is best to look for a company with a strong past performance record in the specific category of testing you require. In other words, look for a company that specializes in testing aerospace wires and cables. Secondly, industry best practices indicate that it is important to select a facility that has been accredited in accordance with the recognized ISO/IEC 17025:2005 General Requirements for the Competence of Testing and Calibration Laboratories. This accreditation demonstrates technical competence for a defined scope and in the operation of a laboratory quality management system.
Let’s say you do your due diligence end up considering Lectromec as a provider for aerospace wire testing. Below are three types of aerospace wire tests that Lectromec performs:
Summary of the 3 categories of aerospace wire testing
- New Wire/Cable Certification
- Wire/Cable Comparison
- Wire/Cable Verification
Each of these tests reflects a stage at different points in the wire/cable lifecycle. We will review what is involved in each test and how they may help your particular application needs.
For those looking for system level testing (e.g. electrical arc damage assessment, etc.), you can read Lectromec’s What do the Results of Arc Track Resistance Testing Mean? article.
New Wire/Cable Certification
This test is performed when a customer needs to get their wire onto a platform and the wire needs to be approved. To be an aerospace approved wire/cable, it must go through a variety of tests. Lectromec recently wrote an article discussing the cost of an AS22759/87 certification and what is involved in the process.
Depending on the particular wire/cable being tested, certification may require as few as 10 or as many as 40 tests. The number of tests will be dependent on a couple of things:
- The specification to which the wire/cable is built. The individual specification sheets will identify the tests that must be performed. Some of these tests may need to be performed by a specific lab, but many can be performed by third party labs.
- What the regulations require. Regulations typically require that components match the state of the industry. For example, flammability regulations require self-extinguishing wire/cable once the flame is removed from the sample. All modern aerospace wires meet this requirement. But in some cases, the regulation may require stricter performance characteristics than the industry standard (e.g. smoke density).
- What the customer wants. There are industry standards, there are regulations, and then there is what the client wants. Some aerospace Original Equipment Manufacturers (OEMs) require that wires be designed to their internal specifications.
Most aerospace wire tests can be performed by Lectromec in our ISO 17025:2005 certified laboratory.
Wire/Cable Comparison
The scope of the wire comparison can take many forms and can be done on multiple levels. To comply with industry standards, a wire/cable must meet a minimum requirement across a variety of criteria. For a user, it is beneficial to find products that exceed the minimum requirements. Testing can be performed to determine the best candidate.
Because there are a wide variety of tests that can be performed, it is Lectromec’s recommendation that the factors be narrowed down to a couple of specific parameters. How these are selected should be based on the particular application. For example, if the area is more susceptible to mechanical stresses, then this should be considered.
An alternative is to look for combining some tests. Perhaps the testing would combine the performance of flex testing at an elevated temperature. Another option may be to consider electrical testing during environmental exposure.
Wire/Cable Verification
This test needs to be performed when the wire has been installed on a platform and there is uncertainty as to its current or future performance. Lectromec once had a client who had installed a system on a space-based platform. During the final system check, before the rocket was to be set off, it was determined that the origin of the installed wires could not be identified. Clearly, there would have been a high cost for delaying the launch, removing the payload, and inspecting the wires. In this case, there was still a dozen feet of wire upon which performance verification tests could be performed. In spite of the short length of the sample, Lectromec was able to perform electrical, mechanical, chemical, and thermal analysis testing.
Lectromec has written an article that discusses these tests.
Summing It Up
If you are trying to get aerospace wires tested, you can do it yourself or search for a company that can do the test for you. Due to the high cost of obtaining the necessary testing equipment and difficulty finding qualified staff, finding a wire testing laboratory that can perform the necessary tests will likely be the option most often chosen. Selecting an appropriate facility involves checking the track record and competence of the wire testing laboratory based on a number of specific criteria outlined in this article.
Lectromec has a full range of services to address wire and cable testing needs. We have been in business since 1984. In all likelihood, we have encountered your problem already and know what solution works the best. You can see a list of the tests we perform, along with princing information on our test listing site.
Michael Traskos
President, Lectromec
michael.traskos@lectromec.comMichael has been involved in wire degradation and failure assessments for more than a decade. He has worked on dozens of projects assessing the reliability and qualification of EWIS components. In September 2014, Michael was appointed as an FAA DER with a delegated authority covering EWIS certification.