Part 27 navigation
Part 27 certification-basis support for rotorcraft navigation equipment
This support maps navigation equipment on a normal-category rotorcraft to the Part 27 paragraphs and operational-performance standards it must meet. A certification or engineering lead runs it while assembling a submittal or answering a finding. It covers the sensor inputs the navigation solution depends on, the currency of the navigation database, the DO-178C software level, and alignment with the applicable minimum operational performance standards. You receive a standards map keyed paragraph by paragraph, a gap list tied to the missing evidence, and a closure order that puts the operational-performance findings first.
When this review is needed
- A navigation unit is entering a Part 27 submittal and its operational-performance claims have to be tied to the applicable MOPS.
- An authority finding questions how the navigation solution handles a degraded sensor input.
- The navigation database update process needs to be shown as controlled rather than assumed current.
- The DO-178C software level asserted for the navigation function has to be matched to its failure condition.
The problem
Navigation equipment is judged against operational-performance standards as much as against Part 27 itself, and the two sets of expectations are usually documented separately. The sensor-input handling, the database-currency controls, and the software-level argument each sit in their own report, none of which states plainly how the equipment meets the performance standard the operation requires. When a finding lands on navigation performance, the team has to build that connection under time pressure.
What gets reviewed
- Part 27 paragraphs and the applicable MOPS identified for the navigation function
- Sensor inputs and their handling in normal and degraded conditions traced to evidence
- Navigation database currency and update-integrity controls checked against the standard
- DO-178C software level matched to the navigation function's failure classification
- Operational credit sought mapped to the substantiation that supports it
- Each finding marked supported, partially supported, or open
What gets validated
- The applicable MOPS is named and the equipment's performance is traced to it rather than assumed
- Degraded-input behavior of the navigation solution is substantiated, not left to inference
- Database update and integrity controls meet the standard the operational credit depends on
- The DO-178C level matches the failure-condition classification for the navigation function
- The operational credit claimed is backed by evidence appropriate to that credit
Evidence normally required
- The certification basis and any issue papers on navigation performance
- The applicable MOPS and the equipment's declared performance against it
- Sensor-input specifications and degraded-mode analysis
- Navigation database update procedures and integrity controls
- DO-178C life-cycle data for the navigation software
Common discrepancies
- Performance declared against a MOPS the equipment was never formally shown to meet
- Degraded-input behavior of the navigation solution with no substantiation on file
- Database update controls that do not reach the integrity the operational credit requires
- A software level short of what the navigation failure condition demands
What is at stake
A navigation package that cannot show MOPS alignment cleanly draws findings that question the operational credit the equipment was meant to earn. If the database-currency controls are weak or the software level is short of what the failure condition demands, the equipment can be limited to a lower operational capability than it was designed for, which undercuts the reason it was installed.
Move from findings to resolution
Identify gaps against the means of compliance.
How the work runs
Name the standards
Identify the Part 27 paragraphs and the applicable MOPS for the navigation function.
Trace the performance
Connect sensor handling and operational credit to the evidence that supports the standard.
Check the controls
Confirm database currency and software level meet what the credit requires.
Prioritize closure
Order the open findings so operational-performance items are resolved first.
What the buyer receives
- A Part 27 standards map linking each paragraph and MOPS point to its evidence and status
- A gap list keyed to the missing performance, database, or software evidence
- A closure sequence prioritizing the operational-performance findings
Who uses the output
- Certification leads answering Part 27 findings on navigation performance
- Engineering leads scoping the database and degraded-mode evidence still owed
- Compliance managers tracking the operational credit against open findings
How the work fits into the transaction or program
The mapping connects the Part 27 basis with the operational-performance standard the navigation equipment is meant to satisfy, so the two are answered as one package. It runs before the finding response so the operational credit rests on evidence that names the standard rather than on a general claim of capability.
Start with a single asset
Confirm requirements trace through verification.
Jurisdiction-specific considerations
FAA and EASA reference the operational-performance standards for navigation similarly, but the operational credit each grants and the way it is documented can differ, so the map flags where a navigation package accepted under one authority needs restated evidence for the other.
Regulatory limits
The mapping shows how the navigation equipment's evidence meets the Part 27 basis and its performance standard, and where it falls short. It does not grant operational credit, issue a compliance finding, or make an airworthiness determination, which remain with the authority.
What this review does not cover
- Flight testing or performance testing of the navigation solution
- Building the database update or integrity control process
- Granting operational credit or issuing any approval
Specific to this review
- Navigation equipment lives against a MOPS as much as against Part 27, so a package strong on the airworthiness paragraphs can still fail on the operational-performance standard.
- Database currency is a recurring gap because the equipment is qualified once but the data behind its output changes on a cycle that needs its own controls.
- Degraded-input behavior is where navigation findings concentrate, since the solution has to remain safe when a sensor feeding it drops out or degrades.
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
How does the MOPS relate to the Part 27 basis here?
Part 27 sets the airworthiness expectations for the installation, while the applicable MOPS sets the performance the navigation function has to demonstrate for the operational credit sought. The map ties the equipment's evidence to both, because a gap in either one limits what the equipment can be approved to do.
Relevant glossary terms
Related pages
Where this fits
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