Sensor TSO
TSO compliance evidence support for sensor systems
This support traces a sensor system's TSO evidence from its requirements down through calibration, environmental qualification, and the installation effects that shift its accuracy in place. Sensors are where a claimed measurement meets the physics of where the unit is mounted, so this reads the requirements trace and ARP4754B development data alongside the calibration and DO-160G reports. An engineer who has certified sensors runs it during evidence mapping, before an application or against a finding. You receive a standards map for the article, a gap list, and an ordered path to closing each item.
When this review is needed
- A sensor system is heading toward a TSO application and its requirements trace needs a read before submittal.
- A finding questioned a calibration basis or an accuracy claim and the response has to reach the source data.
- An installation study changed the sensor's error budget and the affected evidence has to be re-mapped.
- A sensor is being carried to a new airframe class where its installation effects differ and reused evidence needs checking.
The problem
A sensor's authorization stands on a chain: the requirements it was built to, the ARP4754B development that shows those requirements were derived and verified, the calibration that gives its readings meaning, and the installation effects that change its accuracy once it is mounted in a real position. When the chain is assembled from separate work products, a requirement can trace nowhere, a calibration can reference an obsolete standard, or the installation error budget can quietly exceed what the accuracy claim allows, and none of it is visible until the links are laid end to end.
What gets reviewed
- Requirements trace from the sensor's top-level requirements to their verification evidence
- ARP4754B development data checked for the derivation and validation of derived requirements
- Calibration evidence tied to the standard and traceability the accuracy claim relies on
- Installation effects and the sensor error budget reconciled with the declared accuracy
- DO-160G qualification categories declared for the sensor checked against test reports
What gets validated
- Each top-level sensor requirement traces to a verification result, with no requirement stranded
- Derived requirements show the ARP4754B validation rationale rather than appearing without a basis
- Calibration evidence references a current traceable standard, not one that has been superseded
- The installation error budget stays within the accuracy the article's TSO claim declares
- Declared DO-160G categories match the environments the sensor is being authorized for
Evidence normally required
- The draft TSO application or the finding to be answered for the sensor
- The requirements trace matrix and verification results
- ARP4754B development and validation data
- Calibration procedures, results, and traceability records
- Installation effects analysis and the sensor error budget
Common discrepancies
- A top-level requirement with no verification evidence closing it
- A derived requirement present with no ARP4754B validation rationale behind it
- Calibration evidence referencing a superseded measurement standard
- An installation error budget that consumes more accuracy than the claim allows
What is at stake
A sensor package with a broken requirements trace or an accuracy claim the installation cannot honor draws a finding that reopens the error budget, which is among the hardest sensor evidence to rework because it touches development, calibration, and installation at once. Left unmapped, the gap surfaces after the article is fielded on a new position, where correcting it is far more disruptive than closing it at authorization.
Move from findings to resolution
Identify gaps against the means of compliance.
How the work runs
Lay out the chain
Establish the sensor's requirements, development, calibration, and installation basis end to end.
Test the trace
Confirm each requirement reaches a verification result and each derived requirement its validation.
Reconcile the error budget
Check that installation effects leave the declared accuracy intact.
Sequence the closures
Order the gaps by how deep into the chain they reach against the timeline.
What the buyer receives
- A standards map linking each sensor requirement and accuracy claim to its evidence
- A gap list ranked by how deeply each item reaches into the development chain
- A closure sequence ordering the trace, calibration, and installation work that remains
Who uses the output
- Certification engineers assembling the sensor's TSO application
- Compliance managers deciding which trace or calibration gaps block submittal
- Engineering leads directing the development and installation work that closes them
How the work fits into the transaction or program
The mapping runs where the requirements, development, calibration, and installation threads have to meet, laying the chain end to end so a broken link is visible before an authority finds it. Its gap list drives the trace and calibration closures, and its standards map is the reference the error-budget finding responses return to.
Start with a single asset
Confirm requirements trace through verification.
Jurisdiction-specific considerations
Sensor accuracy expectations and the acceptable calibration traceability can be read differently across the FAA and European systems, so a calibration chain that satisfies one authority may need an additional traceability step for the other. The mapping flags where the sensor's calibration basis rests on a national standard the second authority treats differently.
Regulatory limits
The mapping evaluates the sensor's evidence chain and reports its state. It does not authorize the article, validate a calibration on an authority's behalf, or make an airworthiness determination on the sensor or its installation.
What this review does not cover
- Performing the missing verification, calibration, or installation analysis
- Filing the TSO application for the supplier
- Any installation or airworthiness determination on the fitted sensor
Specific to this review
- The installation error budget is the sensor claim most likely to quietly break, because accuracy demonstrated on the bench can be eroded by the real mounting position.
- A stranded derived requirement is a common ARP4754B finding, since derivation is easy to record and validation rationale is easy to skip.
- Calibration traceability decays when a referenced standard is superseded mid-program, so an accuracy claim can rest on a chain no longer considered current.
Sources
U.S. Government (eCFR). Type certificates, STCs (Subpart E), TSO authorizations (Subpart O), PMA (Subpart K), and export airworthiness approvals (Subpart L).
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
Does this cover the installation, or only the sensor unit itself?
It covers the installation effects as they bear on the article's accuracy claim, since a sensor's declared accuracy only holds if the mounting position respects its error budget. It does not perform an installation approval. Where the error budget breaks against the installation, the map flags it so the accuracy claim and the installation study can be reconciled.
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.