Understanding TSO Certification in Aviation Headsets:
If you're in the market for an aviation microphone assembly to use with your consumer headphones, you've likely come across products advertising the use of "TSO'd" BOSE or David Clark microphone capsules. Many of these products claim to be "legal" for use in Part 121 operations, but are they truly TSO-compliant?
1. TSO Certification Applies to the Entire Assembly—Not Just One Component
- A product must be tested and approved as a complete unit to be TSO-certified. This includes the electronics, wiring, housings, and overall construction.
- Simply attaching a TSO-certified microphone to a cable assembly does not make the entire system TSO-compliant.
FAA regulations specifically state that TSO authorization applies to the full design, not just to individual parts. This is outlined in TSO-C139, which governs aviation headsets.
2. TSO-Certified Products Require Strict Quality Assurance & FAA Oversight
Every TSO-certified product must be manufactured under an FAA-approved Quality Assurance program, ensuring that each unit produced meets strict performance and safety standards.
According to FAA Regulation 14 CFR § 21.607, manufacturers must:
- Implement an FAA-approved quality control system that ensures consistent production quality and traceability from part source to the end customer.
- Be subject to regular FAA inspections to verify compliance with TSO standards.
In contrast, products that simply attach TSO’d microphones are not produced under these strict FAA regulations and therefore do not meet the full certification and quality control requirements.
For reference, all manufacturers with a current TSO Authorization (TSOA)—including UFlyMike—can be found in the official FAA database here: FAA TSO Authorization List
3. FAA Regulations Prohibit Unauthorized Design Changes to TSO-Certified Components
Even if an individual TSO-certified component (such as a microphone) is used, modifying the original design invalidates TSO compliance unless the modification is FAA-approved.
According to FAA Regulation 14 CFR § 21.619(c):
“No design change by any person (other than the manufacturer who provided the statement of conformance for the article) is eligible for approval under this part unless the person seeking the approval is a manufacturer and applies under § 21.603(a) for a separate TSO authorization.”
In plain terms:
- Only the original manufacturer of a TSO-certified aviation headset can modify or approve design changes.
- Attaching a TSO microphone to a non-TSO cable assembly does not make it TSO-certified.
Bottom Line:
So, are these products TSO legal for commercial operations? According to the FAA rules, the answer appears to be no. Perhaps this is why these third-party microphone assemblies clearly state that the TSO certification applies to the "microphone only."
Caveat Emptor!