Part 23 displays
Part 23 certification basis support for display systems
This support reconciles a display system's evidence with the Part 23 certification basis of the normal-category aircraft it is installed in. It is used by suppliers and modifiers whose software lifecycle data, human-factors case, and environmental qualification were built for the unit and now have to answer the aircraft basis for how the display presents information and behaves when it fails. The work checks the software level against the failure effect of misleading information, tests the human-factors assumptions against the real cockpit, and confirms the environmental case for the panel location. You receive a display basis map, a list of items the evidence does not yet address, and an ordered path to close them.
When this review is needed
- A display unit's software and human-factors evidence has to answer the Part 23 basis for the normal-category aircraft it is going into.
- The failure effect of misleading information has to be assessed and the software level reconciled to it.
- The human-factors case assumes a cockpit and lighting environment the aircraft may not match.
- A finding asks how the display's failure behavior and information integrity meet a named basis paragraph.
The problem
A display system carries two heavy files, software lifecycle data and a human-factors case, and both are usually built for the unit rather than the aircraft. The Part 23 basis cares about what the display shows the crew and what happens when it shows the wrong thing: misleading information is often the driving failure condition, and the software level has to match that effect. The human-factors argument assumes readability and layout conditions that the actual panel, glare, and lighting may not deliver, and those assumptions are rarely retested against the installed cockpit.
What gets reviewed
- The Part 23 basis paragraphs the display function answers at the aircraft's amendment level
- The failure effect of misleading or lost information and the software level it requires
- Software lifecycle data at the assurance level the failure effect justifies
- Human-factors assumptions on readability, symbology, and layout against the real cockpit
- Environmental qualification for the panel location, including lighting, temperature, and vibration
- The line between coverage the evidence demonstrates and coverage the package assumes
What gets validated
- The failure effect of misleading information is assessed and the software level matches it
- Software lifecycle data supports the assurance level the display's failure effect justifies
- Human-factors claims on readability and symbology trace to an evaluation of the intended cockpit
- Environmental qualification covers the display location's lighting, temperature, and vibration
- Display behavior on partial or total failure is substantiated rather than inferred from the specification
Evidence normally required
- The certification basis for the normal-category aircraft and its amendment level
- The display software lifecycle summary and the assigned software level
- The human-factors evaluation and the symbology and readability assumptions
- Environmental qualification reports for the display unit
- The intended panel layout, lighting environment, and failure-annunciation scheme
Common discrepancies
- A software level set below what the misleading-information failure effect requires
- A human-factors case built on a reference cockpit rather than the installed panel and lighting
- Display failure behavior asserted in the specification but not substantiated by test
- Environmental qualification that omits the lighting or glare condition of the actual location
What is at stake
A display package with software and human-factors evidence that does not tie to the basis leaves the misleading-information failure and the installed-readability questions to surface as findings. Raising a software level to match a misleading-information effect late means reworking assurance evidence, and re-doing a human-factors evaluation against the real cockpit is slow, so both hit the certification date hard when they arrive at the end.
Move from findings to resolution
Identify gaps against the means of compliance.
How the work runs
Classify the failure effect
Establish the effect of misleading and lost information for this cockpit and the software level it drives under the Part 23 basis.
Map software to effect
Reconcile the display software lifecycle data to the assurance level the failure effect justifies and mark the gap.
Test the human-factors case
Check readability, symbology, and layout assumptions against the installed panel and its lighting.
Sequence the closure
Order 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 display evidence behind it
- A gap list emphasizing the misleading-information effect and the installed human-factors case
- A closure sequence ordering the gaps by the software or human-factors rework each implies
Who uses the output
- Certification leads building the display compliance argument for a normal-category modification
- Engineering teams reconciling the software level to the misleading-information failure effect
- Compliance managers answering a finding on display integrity and failure behavior
How the work fits into the transaction or program
The mapping brings the display's software and human-factors files together against the aircraft basis, where the misleading-information effect and installed readability decide compliance. Its gap list drives the assurance and human-factors 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
On a normal-category aircraft the failure effect of a misleading display depends on how much the crew relies on it and what backup exists, so the same display can carry a different software level on a type with independent standby instruments than on one without. The mapping is scoped to the aircraft's cockpit architecture, because the effect classification and the human-factors environment both follow from it.
Jurisdiction-specific considerations
FAA and EASA both drive display assurance from the failure effect but reference different human-factors and design advisory material, so a display argument accepted under one basis can leave items open for the other. The mapping flags where the human-factors expectation and the supporting material differ between authorities.
Regulatory limits
The work reconciles display evidence to the basis and marks the shortfalls. It makes no compliance finding, assigns no software level on the authority's behalf, and issues no approval. The applicant owns the effect classification and the authority makes the findings.
What this review does not cover
- Making official compliance findings or acting as the authority or its delegate
- Running the human-factors evaluation or the display environmental campaign itself
- Any airworthiness determination on the installed display system
Specific to this review
- Misleading information is usually the driving failure condition for a display, so the software level follows that effect rather than the loss-of-function case.
- The human-factors case breaks most often on lighting and glare: an evaluation done in a reference cockpit does not carry to a panel with different geometry and different ambient light.
- The presence or absence of independent standby instruments on the aircraft can change the display's failure-effect classification, and with it the software level the basis demands.
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
Why does the software level depend on the aircraft rather than the display alone?
The Part 23 basis drives the software level from the failure effect, and that effect depends on how the crew uses the display and what backup the aircraft carries. The mapping ties the display's assurance evidence to the effect classification for this specific cockpit.
Relevant glossary terms
Related pages
Where this fits
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