Part 23 sensors
Part 23 certification basis support for sensor systems
This support traces a sensor system's evidence to the Part 23 certification basis of the normal-category aircraft it feeds. Suppliers and modifiers use it when an air-data, attitude, or engine sensor was developed to a requirement set that does not obviously answer the aircraft basis for accuracy, calibration, and behavior when the measurement degrades. The work follows the requirements trace, checks the calibration evidence, tests the environmental case for the sensor's location, and examines how the installation itself affects what the sensor reads. You receive a sensor basis map, a list of items the evidence does not reach, and an ordered plan to close them ahead of submittal or a finding.
When this review is needed
- A sensor system's evidence has to answer the Part 23 basis for the normal-category aircraft it is installed on.
- The installation itself affects the measurement, such as probe placement or a pneumatic run, and the effect has to be accounted for.
- Calibration evidence has to be shown adequate for the accuracy the sensor's function requires.
- A finding asks how the sensor's behavior on degraded or lost measurement meets a named basis paragraph.
The problem
A sensor is only as good as its installation, and the Part 23 basis knows it. An air-data probe reads what the local flow gives it, an attitude source depends on how it is mounted, and an engine sensor sees the environment of its location. The development evidence usually characterizes the sensor in isolation, with a clean calibration and a bench environment, and says little about the installation effects that actually determine accuracy on the aircraft. The requirements trace that should connect the sensor's behavior to the basis is often incomplete at exactly the degraded-measurement cases the basis cares about most.
What gets reviewed
- The Part 23 basis paragraphs the sensor function answers at the aircraft's amendment level
- The requirements trace from sensor behavior through to the basis, including degraded cases
- Calibration evidence and its adequacy for the accuracy the function requires
- Environmental qualification against the sensor's actual location and its conditions
- Installation effects on the measurement, such as probe placement, mounting, or pneumatic routing
- The distinction between accuracy demonstrated in isolation and accuracy in the installed configuration
What gets validated
- Each sensor-related basis paragraph traces to evidence, including the degraded and lost-measurement cases
- Calibration evidence supports the accuracy the sensor function requires for this aircraft
- Environmental qualification matches the sensor's installed location and its conditions
- Installation effects on the measurement are characterized rather than assumed away
- Behavior on a failed or out-of-tolerance sensor is substantiated, not inferred from the datasheet
Evidence normally required
- The certification basis for the normal-category aircraft and its amendment level
- The sensor requirements, development data, and the trace assembled so far
- Calibration procedures and results for the sensor system
- Environmental qualification reports for the sensor unit
- The installation drawings, mounting details, and any pneumatic or routing arrangement
Common discrepancies
- A requirements trace that stops short of the degraded and lost-measurement cases the basis asks about
- Calibration adequate on the bench but never characterized for the installed configuration
- An installation effect on the measurement, such as probe placement, left out of the accuracy case
- Sensor failure behavior asserted from the datasheet without substantiation
What is at stake
A sensor package that maps to its own requirements but not to the aircraft basis leaves the installation-driven accuracy and the degraded-measurement behavior unexamined until a finding forces them. Correcting an installation effect can mean relocating a probe or re-characterizing the calibration in the installed configuration, and either reaches back into airframe work that is expensive to reopen once the aircraft is built.
Move from findings to resolution
Identify gaps against the means of compliance.
How the work runs
Set the sensor basis
Establish the Part 23 basis paragraphs the sensor function answers for this aircraft and its amendment level.
Follow the trace
Trace sensor behavior through to the basis, including degraded and lost-measurement cases, and mark where the trace breaks.
Characterize the install
Check calibration and accuracy in the installed configuration, accounting for placement and mounting effects.
Order the closure
Prioritize the gaps by the rework each forces and deliver a basis map for the matrix.
What the buyer receives
- A basis map linking each relevant Part 23 paragraph to the sensor evidence behind it
- A gap list emphasizing installation effects and degraded-measurement behavior
- A closure sequence ordering the gaps by the airframe or calibration rework each implies
Who uses the output
- Certification leads building the sensor compliance argument for a normal-category modification
- Engineering teams characterizing installation effects and degraded-measurement behavior
- Compliance managers answering a finding on sensor accuracy and failure behavior
How the work fits into the transaction or program
The mapping ties the sensor development file to the aircraft basis, where installation effects and degraded behavior decide compliance. Its gap list drives the installed-accuracy and failure-behavior work, and the basis map feeds the compliance matrix the applicant carries into review.
Start with a single asset
Confirm requirements trace through verification.
Aircraft-specific considerations
Installation effects on a sensor are airframe-specific: the same air-data probe reads differently behind different noses, and the same attitude source behaves differently on different mounts. The mapping is scoped to the aircraft's geometry and installation, because the accuracy and degraded-measurement behavior the basis asks about follow from where and how the sensor is fitted.
Jurisdiction-specific considerations
FAA and EASA reference sensor and system-development guidance that broadly aligns but differs in accepted means of showing installed accuracy, so a sensor argument accepted under one basis can leave items open for the other. The mapping notes where the installed-accuracy evidence changes between authorities.
Regulatory limits
The work traces sensor evidence to the basis and marks the gaps. It makes no compliance finding, issues no approval, and does not determine that the sensor installation is airworthy. Those decisions rest with the applicant and the authority.
What this review does not cover
- Making official compliance findings or acting as the authority or its delegate
- Performing the installed calibration or the sensor environmental campaign itself
- Any airworthiness determination on the installed sensor system
Specific to this review
- Sensor accuracy is set as much by the installation as by the device, so a bench calibration rarely answers the installed-accuracy basis item on its own.
- The requirements trace for a sensor breaks most often at the degraded and lost-measurement cases, which are exactly the failure conditions the Part 23 basis is guarding against.
- Air-data probe placement and pneumatic routing produce airframe-specific errors, so the installed configuration has to be characterized rather than assumed from the device datasheet.
Sources
U.S. Government (eCFR). Type certificates, STCs (Subpart E), TSO authorizations (Subpart O), PMA (Subpart K), and export airworthiness approvals (Subpart L).
Federal Aviation Administration. FAA type certification process, certification basis establishment, and compliance findings.
SAE International. Development assurance process at aircraft and system level, including requirements capture and validation.
Frequently asked questions
The sensor is calibrated and qualified. What does the Part 23 review add?
Calibration and qualification describe the device. The Part 23 basis asks about installed accuracy and behavior when the measurement degrades, both of which depend on how the sensor is fitted to this aircraft. The mapping shows where the device-level evidence leaves installed basis items open.
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.