Surveillance STC
Surveillance equipment installation evidence for an STC approval
This support builds the installation side of a surveillance article's case for an STC approval. It works from the article's own qualification into the aircraft, checking that antenna siting, structural provisions, bonding, and interface wiring are substantiated against the type design the modification touches. A certification engineer runs it while the installation data package is being drafted, so the airframe-level evidence is tested before the STC application is filed. You receive a product-specific evidence gap list, a trace map from installation claims to the certification basis and means of compliance, and a closure sequence for the STC installation approval.
When this review is needed
- A transponder or ADS-B article authorized at the equipment level now has to be installed under an STC and the airframe evidence needs a read.
- Antenna placement on the aircraft raises a co-site or shadowing question the installation data has to answer.
- The modification affects structure or wiring covered by the type design and the substantiation has to reach the certification basis.
- The same STC is being extended to another airframe variant and the installation evidence has to be checked for that effectivity.
The problem
An article that passed its own qualification still has to survive the airframe it is fitted to. Antenna siting drives shadowing and co-site interference, bonding and lightning provisions have to meet the installed environment, and interface wiring has to be substantiated against the loads and separation the type design assumes. Installation data is often drafted late, after the equipment evidence is settled, so the airframe-level questions surface when the schedule has the least room for them.
What gets reviewed
- Antenna siting and its shadowing and co-site substantiation against the installed configuration
- Structural and bonding provisions for the article checked against the type design the STC modifies
- Interface wiring, loads, and separation traced to the aircraft's electrical and physical assumptions
- The article's equipment-level qualification carried into the installation environment it now sees
- The certification basis and means of compliance confirmed for the installed function
- Effectivity of the installation evidence reconciled to the airframe variants the STC claims
Scope this review
Tell us the asset, the event, and the evidence in scope, and we will outline a focused first engagement.
Identify what is missing against the means of compliance.
What gets validated
- Antenna placement in the installation data is supported by a shadowing or co-site assessment, not a drawing alone
- Bonding and lightning provisions meet the zone the article sits in on this airframe
- Interface loads in the wiring substantiation stay inside the type design's assumptions for the affected circuits
- The environmental qualification the article carries covers the conditions its installed location actually sees
- Installation effectivity in the evidence matches the airframe variants named in the STC application
Evidence normally required
- The STC installation data package draft and the declared certification basis
- Antenna siting drawings with any shadowing or co-site analysis
- Structural, bonding, and lightning substantiation for the installation zone
- Interface control and wiring data for the article's connections to aircraft systems
- The article's equipment-level qualification and its authorization reference
Common discrepancies
- An antenna location shown on a drawing but never substantiated for shadowing against the airframe
- A bonding provision that does not meet the lightning zone the article is installed in
- An interface load the wiring analysis assumed but the type design does not support on that circuit
- Installation evidence written for one variant and claimed against an effectivity it never covered
What is at stake
Installation evidence that does not reach the certification basis leaves the STC exposed at exactly the point the authority focuses on. An unsubstantiated antenna location or an interface load the wiring analysis never covered can force a design change after the drawings are frozen, and a co-site problem found on the aircraft is far more expensive to answer than one caught in the data.
How the work runs
Frame the antenna install
Fix the airframe, the antenna and mounting zone, and the certification basis the installation evidence has to reach.
Trace the airframe claims
Follow siting, bonding, and interface statements to the substantiation that supports each one.
Carry the qualification in
Confirm the article's equipment qualification covers the environment its installed location sees.
Order the antenna install gaps
Sequence the airframe-level items by closure difficulty against the surveillance STC filing date.
What the buyer receives
- A product-specific evidence gap list ranked by how hard each installation item is to close
- A trace map from installation claims to the certification basis and means of compliance
- A closure sequence ordering the airframe-level evidence against the STC filing date
Who uses the output
- Certification engineers drafting the STC installation data package
- Installation design leads deciding whether antenna siting or wiring has to change
- Program managers tracking which airframe-level gaps block the STC application
How the work fits into the transaction or program
The review bridges the equipment authorization and the installation approval, testing whether the evidence that qualified the article survives the aircraft it is fitted to. Its gap list drives the airframe-level substantiation the STC needs, and its trace map ties the installation claims to the same certification basis the equipment evidence was built on.
Start with a single asset
Confirm requirements map to substantiating evidence.
Jurisdiction-specific considerations
An STC accepted under one authority is not automatically valid under another, and the installation substantiation an authority expects can differ even where the article's equipment authorization is shared. The review notes where installation evidence built for one register will need rework for the receiving system.
Regulatory limits
The review reads the installation evidence and shows where it reaches or falls short of the certification basis. It does not grant an STC, approve the installation, or make an airworthiness determination on the modified aircraft.
What this review does not cover
- Producing the missing structural, bonding, or wiring substantiation
- Filing the STC application or its installation data package
- Any airworthiness or return-to-service determination on the modified aircraft
Specific to this review
- A surveillance antenna's location is a certification argument, not just a drawing dimension, because shadowing and co-site interference have to be substantiated against everything else radiating on the airframe.
- Equipment qualification proves the article survives a defined environment; the installation has to prove its actual location falls inside that envelope, and those two documents are written by different teams.
- Effectivity is where installation evidence most often overreaches, because a package written for one variant gets claimed against a fleet it was never analyzed for.
Sources
U.S. Government (eCFR). Type certificates, STCs (Subpart E), TSO authorizations (Subpart O), PMA (Subpart K), and export airworthiness approvals (Subpart L).
European Union / EASA. EASA design and production certification, STCs, ETSO authorizations, and EASA Form 1 release.
RTCA. Environmental qualification test categories and procedures referenced by TSO and equipment qualification.
RTCA. Objectives and lifecycle data for airborne software assurance, by design assurance level (DAL A-E).
Frequently asked questions
The article already has a TSO authorization. Why does the installation still need this?
Equipment authorization proves the article performs in a defined environment. The STC has to prove the aircraft location falls inside that envelope and that siting, bonding, and interfaces meet the type design. Those are separate arguments, and the installation is where authorities most often find the evidence thin.
Relevant glossary terms
Related pages
Where this fits
Talk to an engineer who has done this work
We will walk through your current state, the records or evidence involved, and a scoped first engagement.
Talk through the aircraft, records, evidence, deadline, and next useful step.