CFR Parts Every A&P Student Should Know
When studying for your A&P certificate, it is easy to focus only on tools, electricity, engines, structures, and systems. But regulations are also a major part of becoming an aviation maintenance technician.
You do not need to memorize every word of the Code of Federal Regulations, but you should know which CFR parts apply to aircraft maintenance, mechanic privileges, inspections, records, airworthiness, and repair stations.
For A&P students, the most important regulations are found in Title 14 of the Code of Federal Regulations, usually written as 14 CFR.
In everyday aviation language, these are often still called the FARs, or Federal Aviation Regulations.
What Is the CFR?
CFR stands for Code of Federal Regulations.
For aviation maintenance, the important section is:
Title 14 CFR — Aeronautics and Space
This is where the FAA regulations are organized.
As an A&P student, you do not need to know every part of Title 14, but you should recognize the major parts that affect aircraft mechanics and maintenance.
The Big Ones for A&P Students
14 CFR Part 1 — Definitions and Abbreviations
Part 1 is where many important aviation terms are defined.
This matters because test questions often depend on the exact meaning of words like:
- Aircraft
- Airframe
- Aircraft engine
- Propeller
- Appliance
- Maintenance
- Preventive maintenance
- Major repair
- Major alteration
- Airworthy
A&P tip:
If a test question is asking what something legally means, Part 1 is often where the definition comes from.
14 CFR Part 21 — Certification Procedures for Products and Articles
Part 21 deals with certification of aircraft, engines, propellers, and parts.
This is where you get into topics like:
- Type certificates
- Production certificates
- Airworthiness certificates
- Approved parts
- Replacement and modification articles
For A&P students, Part 21 is important because mechanics must understand that aircraft parts and modifications need proper approval.
A mechanic cannot just install any part that physically fits. The part must be acceptable or approved for the aircraft, engine, propeller, or appliance.
14 CFR Part 39 — Airworthiness Directives
Part 39 covers Airworthiness Directives, usually called ADs.
An AD is a legally enforceable rule issued by the FAA to correct an unsafe condition.
For A&P test purposes, remember:
- ADs are mandatory.
- ADs may require inspections, repairs, replacements, limitations, or modifications.
- An aircraft is not airworthy if it does not comply with applicable ADs.
Simple way to remember it:
AD = mandatory safety correction
If the FAA says an AD applies, it must be complied with unless an approved alternative method of compliance is allowed.
14 CFR Part 43 — Maintenance, Preventive Maintenance, Rebuilding, and Alteration
Part 43 is one of the most important CFR parts for an A&P mechanic.
This part explains who can perform maintenance and how maintenance must be recorded.
Part 43 includes rules for:
- Maintenance
- Preventive maintenance
- Rebuilding
- Alterations
- Major repairs
- Major alterations
- Maintenance record entries
- Approval for return to service
One of the most important sections is §43.3, which identifies persons authorized to perform maintenance, preventive maintenance, rebuilding, and alterations.
Another major section is §43.9, which explains what must be included in a maintenance record entry.
A standard maintenance record entry usually includes:
- A description of the work performed
- The date the work was completed
- The name of the person performing the work
- The signature, certificate number, and certificate type of the person approving the work
A&P test tip:
If the question is about maintenance record entries, return to service, major repairs, major alterations, or preventive maintenance, think Part 43.
14 CFR Part 43 Appendix A — Major Repairs, Major Alterations, and Preventive Maintenance
Appendix A to Part 43 is very testable.
It helps identify:
- Major repairs
- Major alterations
- Preventive maintenance items
This is where you go when deciding whether a repair or alteration is major or minor.
Preventive maintenance is also listed here.
Important point:
A pilot may be allowed to perform certain preventive maintenance, but that does not mean a pilot can perform all maintenance. Preventive maintenance is limited.
For A&P students, Appendix A is important because it separates simple maintenance tasks from work that requires higher authorization, records, or inspection.
14 CFR Part 45 — Identification and Registration Marking
Part 45 deals with aircraft identification and marking.
This includes things like:
- Aircraft registration markings
- Nationality marks
- Data plates
- Identification plates
- Marking requirements for aircraft, engines, propellers, and certain parts
For mechanics, the important idea is that aircraft and major products must be properly identified.
A missing, damaged, or improper data plate can become a serious airworthiness issue.
14 CFR Part 65 — Certification: Airmen Other Than Flight Crewmembers
Part 65 is extremely important for A&P students because this is the part that covers mechanic certification.
Part 65 includes rules for:
- Mechanic certificates
- Airframe ratings
- Powerplant ratings
- Inspection Authorization
- Eligibility requirements
- Privileges and limitations
- Experience requirements
This is where the FAA explains what a mechanic certificate allows you to do.
Important point:
An A&P certificate is not unlimited permission to do anything on any aircraft. A mechanic must still work within the privileges and limitations of their certificate, rating, experience, and applicable regulations.
A&P test tip:
If the question is about what a certificated mechanic can or cannot do, think Part 65.
14 CFR Part 91 — General Operating and Flight Rules
Part 91 is mostly thought of as an operating rule section, but it has very important maintenance rules too.
For A&P students, the most important area is:
Part 91 Subpart E — Maintenance, Preventive Maintenance, and Alterations
This section includes rules related to:
- Owner/operator responsibility
- Required inspections
- Annual inspections
- 100-hour inspections
- Altimeter and transponder checks
- Maintenance records
- Airworthiness Directives
- Inspection programs
One of the most important ideas from Part 91 is that the owner or operator is primarily responsible for maintaining the aircraft in an airworthy condition.
That does not remove responsibility from the mechanic, but it does explain who is primarily responsible for making sure the aircraft remains airworthy.
A&P test tip:
If the question mentions annual inspections, 100-hour inspections, aircraft maintenance records, or owner/operator responsibility, think Part 91.
14 CFR Part 145 — Repair Stations
Part 145 covers certificated repair stations.
Repair stations are FAA-approved maintenance organizations.
Part 145 includes rules for:
- Repair station certificates
- Ratings
- Personnel
- Housing and facilities
- Equipment, tools, and materials
- Quality control systems
- Repair station manuals
For A&P students, the big idea is that a repair station can perform maintenance, preventive maintenance, or alterations according to its certificate and ratings.
A repair station does not automatically have permission to perform every kind of maintenance. It must be rated for the work being performed.
14 CFR Part 147 — Aviation Maintenance Technician Schools
Part 147 covers FAA-certificated aviation maintenance technician schools.
This is the regulation that applies to approved A&P schools.
Part 147 includes requirements for:
- School certification
- Curriculum
- Facilities
- Equipment
- Instructors
- Operating rules
If you are attending an FAA-approved A&P school, Part 147 is the regulation that applies to that school.
A&P test tip:
If the question is about certificated aviation maintenance technician schools, think Part 147.
Other CFR Parts Worth Recognizing
The following parts are not always the main focus for A&P students, but you should recognize them.
14 CFR Part 23 — Normal Category Airplanes
Part 23 covers airworthiness standards for normal category airplanes.
These are design and certification standards, not mechanic privilege rules.
14 CFR Part 25 — Transport Category Airplanes
Part 25 covers airworthiness standards for transport category airplanes.
This applies to larger transport aircraft.
14 CFR Part 27 — Normal Category Rotorcraft
Part 27 covers normal category rotorcraft.
14 CFR Part 29 — Transport Category Rotorcraft
Part 29 covers transport category rotorcraft.
14 CFR Part 33 — Aircraft Engines
Part 33 covers airworthiness standards for aircraft engines.
14 CFR Part 35 — Propellers
Part 35 covers airworthiness standards for propellers.
The Most Testable CFR Parts
If you are studying for the A&P exam and want to prioritize, focus on these first:
| CFR Part | Main Topic | Why It Matters |
|---|---|---|
| Part 1 | Definitions | Explains legal meanings of aviation terms |
| Part 21 | Certification procedures | Covers aircraft, engine, propeller, and parts certification |
| Part 39 | Airworthiness Directives | ADs are mandatory |
| Part 43 | Maintenance and records | Core mechanic maintenance rules |
| Part 43 Appendix A | Major/minor repairs and preventive maintenance | Helps classify maintenance work |
| Part 45 | Identification and markings | Data plates and aircraft markings |
| Part 65 | Mechanic certification | Mechanic privileges and limitations |
| Part 91 Subpart E | Maintenance and inspection rules | Annuals, 100-hour inspections, records, owner/operator responsibility |
| Part 145 | Repair stations | Rules for certificated repair stations |
| Part 147 | AMT schools | Rules for approved A&P schools |
Easy Memory Aid
Here is a simple way to remember the big CFR parts:
1 defines, 21 certifies, 39 mandates, 43 maintains, 65 certifies mechanics, 91 operates, 145 repairs, 147 teaches.
Or even shorter:
43 is the work. 65 is the mechanic. 91 is the aircraft owner/operator responsibility.
Common A&P Test Traps
Trap 1: Thinking the mechanic is always primarily responsible for airworthiness
The owner or operator is primarily responsible for maintaining the aircraft in an airworthy condition.
However, the mechanic is responsible for the work they perform and the approval for return to service they sign.
Trap 2: Thinking preventive maintenance means any simple maintenance
Preventive maintenance is not just any easy job.
Preventive maintenance is specifically limited by regulation.
If it is not listed as preventive maintenance, do not assume it qualifies.
Trap 3: Thinking all repairs are treated the same
Repairs may be major or minor.
Major repairs require specific documentation and approved data.
Minor repairs are still maintenance, but they do not have the same documentation requirements as major repairs.
Trap 4: Thinking an A&P can automatically perform inspections
A mechanic with an airframe and powerplant rating can perform many maintenance tasks, but certain inspections and approvals may require additional authorization, such as an Inspection Authorization.
Trap 5: Confusing Part 43 and Part 65
Part 43 tells you the rules for performing and recording maintenance.
Part 65 tells you about mechanic certification, privileges, and limitations.
Simple version:
Part 43 = maintenance rules
Part 65 = mechanic certificate rules
Final Study Takeaway
For the A&P test, you do not need to memorize the entire CFR.
But you should know which regulation applies to which situation.
The most important ones are:
- Part 43 for maintenance, records, and return to service
- Part 65 for mechanic privileges and certification
- Part 91 for inspection requirements and owner/operator responsibility
- Part 39 for Airworthiness Directives
- Part 145 for repair stations
- Part 147 for aviation maintenance technician schools
If you can recognize what each part is for, you will be much more comfortable with FAA regulation questions on the written, oral, and practical exams.
Quick Review
Before your test, make sure you can answer these:
- Which CFR part covers maintenance, preventive maintenance, rebuilding, and alteration?
- Which CFR part covers mechanic certification?
- Which CFR part covers Airworthiness Directives?
- Which CFR part covers repair stations?
- Which CFR part covers aviation maintenance technician schools?
- Who is primarily responsible for maintaining an aircraft in an airworthy condition?
- Where would you look to determine whether something is preventive maintenance?
- What information is required in a maintenance record entry?
If you can answer those, you are on the right track.