Airworthiness Requirements and Regulations for Avionics Maintenance
What this domain tests
This domain tests how avionics maintenance is kept airworthy: what data you may use, how modifications are approved, how airworthiness directives and service information apply, and how equipment approval differs from installation approval.
Core rules and concepts
- Maintenance must use approved data: the manufacturer's maintenance manual, structural repair manual, service bulletins incorporated as required, or an approved supplemental type certificate (STC).
- Airworthiness directives are mandatory. Service bulletins are generally recommended unless an AD, the operator's programme or the State makes them mandatory.
- Parts need a documentation trail: a Form 1 or 8130-3 (or equivalent) establishes airworthiness status. A TSO authorisation shows the article meets a minimum performance standard, not that it is approved for a particular installation.
- Major modifications or repairs require approved data and often an STC. Minor modifications may be handled under an approved maintenance organisation's procedures using acceptable data.
- Operational approvals such as RVSM, ADS-B Out and ELT are separate from the physical installation: equipment must meet the performance and certification requirements, and the aircraft must be approved and recorded as such.
Worked example
An operator wants to fit an ADS-B Out transponder. A TSO'd transponder is necessary but not sufficient. The installer must use approved installation data, verify the position source and system interfaces, complete the required ground and flight tests, update the aircraft records and obtain any operational approval. Signing the job off as "transponder replaced" misses the system and approval aspects.
Traps that cost marks
- Assuming every service bulletin is mandatory.
- Treating TSO approval as installation approval.
- Using acceptable data for a major modification.
- Forgetting that RVSM and ADS-B approvals are system approvals, not just box approvals.