Part 27 certification basis
Part 27 certification-basis support for equipment on normal-category rotorcraft
Part 27 certification-basis support helps a supplier whose equipment installs on a normal-category rotorcraft establish and trace the basis its installation approval rests on. It is used by avionics and equipment teams whose article goes into rotorcraft certified under 14 CFR Part 27. The work fixes the applicable amendment, accounts for the rotorcraft-specific vibration, environmental, and installation conditions, and traces compliance evidence to each applicable section. You receive a basis map and a gap assessment ready for review.
When this review is needed
- Equipment is being installed on a normal-category rotorcraft and the applicable Part 27 amendment has to be fixed before compliance work begins.
- The rotorcraft vibration and environmental signature differs from the airplane case the equipment was qualified for and the gap has to be addressed.
- An installation depends on the rotorcraft's electrical and HIRF environment and the qualification has to reflect it.
- A supplier wants the Part 27 basis and the rotorcraft-specific qualification read independently before submittal.
The problem
Equipment carried onto a rotorcraft from an airplane installation runs into a different physical environment, and the basis work is where that difference surfaces or gets missed. The rotorcraft vibration spectrum is harsher and tonal in ways fixed-wing qualification does not capture, the electrical and HIRF environment is its own case, and the applicable Part 27 amendment is assumed rather than fixed. An installation whose qualification was built for an airplane and never re-examined for the rotorcraft draws environmental findings that reach back into testing.
What gets reviewed
- The applicable Part 27 amendment for the rotorcraft and the installation
- The applicable sections for the specific equipment on the rotorcraft
- The rotorcraft vibration environment against the equipment qualification
- The electrical, HIRF, and environmental conditions the installation imposes
- How each applicable section is shown to be met for the installation
- Software and qualification data consistent with the installation argument
What gets validated
- The applicable Part 27 amendment is fixed for the rotorcraft and installation
- Every applicable section is identified for the equipment on this rotorcraft
- The vibration qualification reflects the rotorcraft spectrum rather than an airplane case
- The electrical and HIRF environment of the rotorcraft is covered by qualification
- Installation evidence maps to each applicable section and supports the claim
- Software and qualification data are consistent with the installation argument
- Environmental categories carried over from prior installations are re-validated
Evidence normally required
- The rotorcraft type data and the Part 27 amendment in question
- The equipment specification and its intended installation on the rotorcraft
- Existing qualification evidence and the environment it was built for
- The rotorcraft vibration, electrical, and HIRF environment data
- Software evidence assembled for the equipment
Common discrepancies
- Vibration qualification carried from an airplane case that the rotorcraft spectrum exceeds
- An applicable Part 27 amendment assumed rather than confirmed
- HIRF or electrical environment of the rotorcraft not reflected in qualification
- Applicable sections missed for the specific equipment on the rotorcraft
- Installation evidence that does not trace to an applicable section
- Environmental categories copied across installations without re-validation
What is at stake
When the qualification does not reflect the rotorcraft environment or the basis is loose, the installation approval waits while the equipment is re-qualified against the real conditions. The delay holds the equipment off the rotorcraft and consumes the test capacity the program planned for elsewhere.
Move from findings to resolution
Identify gaps against the means of compliance.
How the work runs
Fix the amendment
Confirm the applicable Part 27 amendment for the rotorcraft and the equipment installation.
Scope the sections
Identify the sections that apply to the specific equipment on this rotorcraft.
Re-examine the environment
Compare the equipment qualification against the rotorcraft vibration, electrical, and HIRF conditions.
Trace and package
Map evidence to each applicable section and produce a prioritized closure list.
What the buyer receives
- A Part 27 certification-basis map fixed to the applicable amendment
- A means-of-compliance plan reflecting the rotorcraft environment
- A section-to-evidence trace for the installation
- A prioritized list of the qualification and basis gaps to close
Who uses the output
- Certification leads preparing the rotorcraft installation approval data
- Engineering teams closing the qualification and evidence gaps
- Program management sequencing the remaining compliance work
How the work fits into the transaction or program
The work supports the supplier's own Part 27 installation program. It re-examines the qualification against the rotorcraft environment and fixes the basis before submittal so the environmental questions are answered in the evidence rather than in review.
Start with a single asset
Confirm requirements trace through verification.
Aircraft-specific considerations
Part 27 covers normal-category rotorcraft, where the rotor-induced vibration spectrum and the electrical and HIRF environment differ from a fixed-wing installation. Qualification that satisfied an airplane case is re-examined against the specific rotorcraft, so the basis work is anchored to the rotorcraft type data and its physical environment rather than to the equipment's prior approvals.
Regulatory limits
Endeavor Elements supports the applicant's certification basis and compliance evidence. It does not establish the basis on the authority's behalf, accept qualification on the authority's behalf, or guarantee approval. The authority sets the basis and makes the findings.
What this review does not cover
- Establishing the certification basis on the authority's behalf
- Issuing any approval or making official compliance findings
- Performing the vibration or environmental testing itself
Specific to this review
- Normal-category rotorcraft have a vibration environment that is harsher and more tonal than the fixed-wing case, so equipment qualified for an airplane cannot be assumed to qualify on a rotorcraft.
- The rotorcraft electrical and HIRF environment is its own qualification case, and carrying over an airplane environment is a recurring source of environmental findings.
- Vibration is the section that most often reopens on a rotorcraft installation, because the rotor-induced spectrum is specific to the airframe and rotor system.
- Normal-category rotorcraft under Part 27 are weight-limited and seat-limited, which fixes which installation conditions apply and distinguishes them from the transport-category rotorcraft case.
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.
RTCA. Environmental qualification test categories and procedures referenced by TSO and equipment qualification.
Frequently asked questions
Our equipment is already qualified for an airplane. Does it carry to a rotorcraft?
Not automatically. The rotorcraft vibration and HIRF environment is a distinct case, and the qualification is re-examined against it. Vibration is the section that most often needs re-work.
How is Part 27 different from the transport-category rotorcraft rule?
Normal-category rotorcraft are weight- and seat-limited. That bounds which conditions apply and separates them from the transport-category rotorcraft basis.
Relevant glossary terms
Related pages
Where this fits
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