As an AS9120-A–certified supplier of aircraft components to the Defense Logistics Agency (DLA), the Department of Defense (DoD), and aerospace contractors, we often encounter situations where we need to understand the meaning of 121 Trace and 129 Trace (trace is referring to traceability paperwork for a component). Often times, the parts we supply are obsolete or very difficult to find. Secure Component’s role in our customer’s supply chain is to provide items they are unable to locate within their “authorized supply chain.” In short, we provide additional sourcing horsepower for their supply chain, which ensures that all the available options for parts that meet the acceptable quality, pricing, and timeline requirements for their application have been explored and are included in the quote. In some of our company’s recent interactions with clients, we have noticed confusion regarding 121 and 129 Trace. This post will explain both types of trace and clarify the confusion surrounding the two.
As you read on, you will notice that 121 and 129 Trace are terms referring to the traceability of commercial-grade airline equipment. I decided to write this post because, in military applications, a commercial part can often be of dual use, making them acceptable depending on the end-use of the item. An example of this is the Boeing 707, which is a commercial airplane. The military equivalents of the Boeing 707 are the E-3 and the C-137, and in certain situations, the military can use commercial components. To be clear, engineering will absolutely need proper documentation of the authenticity of the part in order to approve its usage. This is where a clear understanding of 121 and 129 Trace can be of great value.
The Difference between 121 Trace and 129 Trace
To understand the differences between 121 and 129 Trace, the meaning of these two terms must first be understood. These two numbers refer to two parts of the Federal Acquisition Regulations (FAR). In general, part 121 of the FAR pertains only to domestic airlines, whereas part 129 applies to foreign entities.
According to Section 49 of the U.S. Code, “The Administrator of the Federal Aviation Administration shall issue an air carrier operating certificate to a person desiring to operate as an air carrier when the Administrator finds, after investigation, that the person properly and adequately is equipped and able to operate safely under this part and regulations and standards prescribed under this part.”  In other words, components that have 121 Trace are traceable to an airline that has been certified to this part of the FAR, and traceback to the manufacturer can be proven.
Part 129 of the FAR applies to two categories of airlines: “Foreign air carriers with U.S. government permission to operate flights in and out of the United States”; and “Foreign operators of U.S.-registered aircraft who operate their aircraft in common carriage, but operate them entirely outside the United States.”  Components that are traceable to part 129 airlines are referred to as having “part 129 Trace,” or simply “129 Trace.”
Part 145 Trace
An additional type of trace is part 145 Trace. This refers to parts that are traceable to a repair station that is certified to part 145 of U.S. Code Title 14. According to this section of the Code, part 145-certified stations may “perform maintenance, preventive maintenance, or alterations in accordance with part 43 on any article for which it is rated and within the limitations in its operations specifications” . Essentially, if a component has 145 Trace, it has been repaired by a certified FAA repair station, and the work can then be traced back to that specific repair facility, but necessarily the OEM.
Beneficial to Military Applications
Now that you understand the meaning of 121 Trace and 129 Trace, let me provide an example of how this can be beneficial to military applications. If there is demand for a part that goes on the E3 and there is no military-grade stock available, my procurement team could potentially procure the part from a commercial entity, provided it had the proper traceability. At that point, a military engineer could review the application of the proposed component and potentially sign off on its usage. For example, we could potentially locate a part from a Boeing 707 supplier that has 121 Trace with an 8130 tag, and submit it for approval by military engineers. (An 8130 tag is an airworthiness certificate issued by an FAA qualified body.)  In situations where the desired military part is unavailable, this option to utilize commercial components with proper trace has proven to be an extremely valuable option to ensure that the militaries mission remains uninterrupted. After all, that is what we all here to do—support the warfighter and provide them with every option possible so that when they enter the battlefield, they are confidently prepared to fulfill their mission.
Hopefully, this post will clear up some of the confusion surrounding the issue of 121 and 129 Trace and the value that it could provide to certain situations that arise within the military’s supply chain. In the event you encounter a situation where you either need Secure Components to find you a part or you simply have more questions regarding this issue, I would be glad speak with you to help resolve your issue(s). To obtain my contact information or anyone at Secure Components, click here.