Part 27 sensor systems
Part 27 certification-basis support for a rotorcraft sensor system
This support ties a sensor system on a normal-category rotorcraft to the Part 27 paragraphs that govern it and checks that the evidence can carry each one. An engineering or certification lead runs it while preparing a submittal or answering a finding. It reaches across the requirements trace from sensed parameter to output, the calibration evidence, the DO-160G qualification against the rotorcraft environment, and the installation effects that change sensor behavior on the airframe. You receive a paragraph-level standards map, a gap list tied to the missing evidence, and a closure order that starts with the accuracy and integrity findings.
When this review is needed
- A sensor is entering a Part 27 submittal and its accuracy has to be shown at the installed condition on the rotorcraft.
- An authority finding asks how rotorcraft vibration affects the sensor's output and the answer is not assembled.
- Calibration data exists but has never been traced from the sensed parameter to the function the rotorcraft uses.
- A development-assurance argument under ARP4754B has to reach the Part 27 findings it was built for.
The problem
A sensor is calibrated on a bench, but a rotorcraft subjects it to sustained vibration and installation constraints that shift the value the aircraft actually receives. The calibration reports, the requirements trace, and the qualification results usually sit apart from the installation analysis, so the accuracy proven at the component is not obviously the accuracy the Part 27 finding is about. That distance is where a rotorcraft sensor package tends to fall short under a finding.
What gets reviewed
- Part 27 paragraphs applicable to the sensed parameter and the functions consuming it
- The path from sensed quantity through processing to delivered output verified end to end
- Accuracy evidence weighed against the tolerance the rotorcraft finding actually requires
- DO-160G qualification checked against the vibration and temperature the sensor sees where it is mounted
- Installation and vibration effects on accuracy, response, and integrity accounted for
- Each mapped paragraph recorded as met, partly met, or outstanding
What gets validated
- The trace holds from sensed parameter to consuming function with no step left unexplained
- Accuracy evidence carries the tolerance the Part 27 finding demands rather than a benign bench figure
- Rotorcraft vibration and installation effects on the sensor are addressed in the substantiation
- DO-160G categories reflect the rotorcraft environment the sensor is installed in
- The ARP4754B development-assurance level matches the integrity the sensed function demands
Evidence normally required
- The certification basis and issue papers touching the sensor
- The requirements set and the trace matrix through to the delivered output
- Bench calibration procedures and the accuracy results behind them
- DO-160G environmental qualification reports for the sensor unit
- Installation drawings and any vibration or position-error analysis
Common discrepancies
- Calibration proven at the component that never accounts for rotorcraft installation and vibration
- A trace that ends at the sensor output and never carries through to the function using it
- Qualification run to a category that understates the rotorcraft vibration environment
- An integrity claim with no development-assurance evidence for the level asserted
What is at stake
When rotorcraft installation and vibration effects are not accounted for, an authority can treat the sensor's accuracy claim as unsubstantiated at the aircraft level despite sound component data. That reopens the requirements trace and the qualification basis together, and a sensor feeding a display or a control function pulls those downstream systems back into question.
Move from findings to resolution
Identify gaps against the means of compliance.
How the work runs
Scope the basis
Identify the Part 27 paragraphs governing the sensed parameter and the functions that use it.
Walk the trace
Follow the path from sensed quantity to delivered output and mark where it breaks.
Account for the airframe
Confirm calibration, qualification, and vibration effects support the finding's real tolerance.
Order the closure
Rank the outstanding findings so accuracy and integrity items resolve ahead of the rest.
What the buyer receives
- A Part 27 standards map tying each sensor paragraph to its evidence and its status
- A gap list naming the calibration, trace, or installation evidence still outstanding
- A closure sequence that clears the accuracy and integrity findings first
Who uses the output
- Certification leads answering Part 27 findings on sensor accuracy and integrity
- Engineering leads scoping the installation and vibration analysis still owed
- Compliance managers watching the sensor's outstanding findings against the submittal date
How the work fits into the transaction or program
The mapping sits after the sensor's component evidence is produced and before the rotorcraft-level substantiation is finalized. It closes the distance between bench accuracy and installed accuracy under rotorcraft vibration, so the trace, the calibration, and the qualification reach the Part 27 findings as one connected argument.
Start with a single asset
Confirm requirements trace through verification.
Jurisdiction-specific considerations
Part 27 and CS-27 treat sensor accuracy and integrity along similar lines, but the acceptable ways of showing installation and vibration effects differ, so the map flags where an installation argument accepted under one authority needs restatement for the other.
Regulatory limits
The mapping shows how the sensor's evidence meets the Part 27 basis and where it does not. It does not issue a compliance finding, approve the sensor or its installation, or make any airworthiness determination, which remain with the authority.
What this review does not cover
- Running new calibration or environmental qualification tests
- Performing the installation or vibration analysis itself
- Issuing any compliance finding or approval on the sensor
Specific to this review
- Sustained rotorcraft vibration can shift a sensor's output in ways a bench calibration never captures, so installed accuracy is the finding that matters most.
- Because sensors feed downstream functions, an unresolved rotorcraft sensor gap propagates into the certification of every system that uses its output.
- Development assurance under ARP4754B sets the integrity floor for the sensed function, and more calibration data cannot substitute for a level that falls short.
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
Does rotorcraft vibration really change what the sensor evidence needs?
Yes. A sensor calibrated on a bench sees a benign environment, but a rotorcraft imposes sustained vibration that can shift its output. Part 27 is concerned with the parameter as installed, so the substantiation has to carry the accuracy claim into the rotorcraft environment rather than resting on component data.
Relevant glossary terms
Related pages
Where this fits
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