Direct Answer — Who Is Responsible and What Proves It
Under 14 CFR §91.403(a), the owner or operator of an aircraft is primarily responsible for maintaining it in an airworthy condition, including compliance with part 39 (airworthiness directives). §91.405 states the recurring duties that discharge that responsibility: have the aircraft inspected per subpart E and discrepancies repaired per part 43; ensure maintenance personnel make an entry indicating the aircraft has been approved for return to service; address inoperative instruments and equipment permitted under §91.213(d)(2); and ensure a placard is installed per §43.11 when listed discrepancies include inoperative items. §91.407 then bars operation after maintenance until a person authorized under §43.7 approves the aircraft for return to service and the §43.9 or §43.11 entry is made — plus an operational-check flight by an appropriately rated pilot before carrying passengers when the work may have appreciably changed the aircraft's flight characteristics. The records that prove each link held are the §43.9 maintenance entry, the §43.11 inspection entry, the return-to-service signature with certificate number, and the inoperative-equipment placard and deferral record.
The mechanic signs for the work; the owner/operator owns the airworthiness
A common and costly misunderstanding: that hiring an A&P transfers the airworthiness responsibility to the shop. It does not. Under 14 CFR §91.403(a) the owner or operator remains primarily responsible for the airworthy condition of the aircraft and for AD compliance. The A&P or repair station is responsible for the specific work they performed and returned to service under §43.7. The owner/operator's defense in an enforcement action is the completeness of the records — which is exactly the layer that fails first.
The Three-Link Chain — §91.403, §91.405, §91.407
Subpart E of part 91 builds the maintenance responsibility in three steps. Each one is a separate regulation with separate verbs, and an inspector reads them as a sequence: who is responsible, what they had to do, and what had to be true before the aircraft flew. Treating them as one vague duty to "keep the plane legal" is how operators miss a specific requirement — and the missing piece is almost always a record.
Link 1 — §91.403 assigns the responsibility
§91.403(a) places primary responsibility for maintaining the aircraft in an airworthy condition — including part 39 compliance — on the owner or operator. §91.403(b) requires that no person perform maintenance, preventive maintenance, or alterations other than as prescribed in subpart E and other applicable regulations, including part 43. §91.403(c) ties maintenance to the manufacturer's airworthiness limitations section: where such a section exists, work must follow its mandatory replacement times and inspection intervals unless an FAA-approved operations specification or a §91.409(e) inspection program sets an alternative. §91.403(d) bars altering an aircraft based on a supplemental type certificate unless the owner/operator holds the STC or has the holder's written permission.
The record this generates: nothing yet — but it establishes who every downstream record is protecting. See the Part 91 aircraft records requirements and how AD compliance records survive a ramp check.
Link 2 — §91.405 states the recurring duties
§91.405 opens "Each owner or operator of an aircraft—" and then lists four duties. (a) Have the aircraft inspected as prescribed in subpart E, and between required inspections have discrepancies repaired as prescribed in part 43. (b) Ensure that maintenance personnel make appropriate entries in the aircraft maintenance records indicating the aircraft has been approved for return to service. (c) Have any inoperative instrument or item of equipment permitted to be inoperative by §91.213(d)(2) repaired, replaced, removed, or inspected at the next required inspection. (d) When listed discrepancies include inoperative instruments or equipment, ensure that a placard has been installed as required by §43.11.
The records this generates: a §43.11 inspection entry, §43.9 repair entries, a return-to-service entry, and an inoperative-equipment placard plus deferral list. This is the link with the most documents — and the most exposure.
Link 3 — §91.407 controls operation after maintenance
§91.407(a) bars operating an aircraft that has undergone maintenance, preventive maintenance, rebuilding, or alteration unless it has been approved for return to service by a person authorized under §43.7 and the maintenance record entry required by §43.9 or §43.11 has been made. §91.407(b) adds that no person may carry any person other than crewmembers in an aircraft maintained, rebuilt, or altered in a manner that may have appreciably changed its flight characteristics or substantially affected its operation in flight until an appropriately rated pilot with at least a private pilot certificate flies it, makes an operational check, and logs the flight in the aircraft records. §91.407(c) permits skipping that flight if ground tests, inspection, or both show conclusively the work has not appreciably changed flight characteristics or substantially affected the flight operation.
The records this generates: the approval-for-return-to-service entry, and — when §91.407(b) applies — the logged operational-check flight in the aircraft records.
Primary regulations cited in this section: 14 CFR §91.403 (General), 14 CFR §91.405 (Maintenance required), 14 CFR §91.407 (Operation after maintenance).
The Records That Discharge the §91.405 Duties
§91.405 is a list of actions, but every action leaves a document, and the document is what proves the action happened. Map each clause of §91.405 to the record that satisfies it, and the recordkeeping obligation becomes concrete.
The inspection itself is governed by §91.409 — annual within the preceding 12 calendar months under §91.409(a); 100-hour where the aircraft carries persons for hire or is used for flight instruction for hire under §91.409(b); or a progressive or approved inspection program under §91.409(d)–(f). The record that proves the inspection happened is a §43.11 inspection entry, not a §43.9 entry. Discrepancies found and repaired between inspections each produce their own §43.9 entry.
- Annual inspection entry (§43.11) signed by an IA — the airworthiness-determination statement
- 100-hour inspection entry (§43.11) where the aircraft is operated for hire or flight instruction for hire
- Each discrepancy repair logged as a §43.9 maintenance entry between inspections
- Open list of discrepancies and unairworthy items, dated and provided to the owner, when an inspection is signed off as not approved
Detail: Part 91.409 annual inspection requirements and the annual/100-hour inspection scope under part 43 appendix D.
This is the owner/operator's affirmative duty to confirm the entry exists — not merely to assume the shop made it. Under §43.9(a), the entry must contain a description of (or reference to data for) the work performed, the date of completion, the name of the person performing the work if different from the approver, and the signature, certificate number, and kind of certificate of the person approving the work for return to service. That §43.9(a)(4) signature is the approval for return to service of the work performed.
Replaced No. 2 main landing gear tire and tube, P/N [____], per AMM Ch. 32. Serviced to [____] psi. Ops check good. Airframe total time: 4,210.3 hrs. [Date]. [A&P name]. A&P Certificate No. [____]. [Signature] — approved for return to service.
Note: an inspection is excluded from §43.9 by §43.9(c) and recorded under §43.11 instead — see the §43.9 maintenance record entry requirements.
§91.405(c): any inoperative instrument or item of equipment permitted to be inoperative by §91.213(d)(2) must be repaired, replaced, removed, or inspected at the next required inspection. §91.405(d): when listed discrepancies include inoperative instruments or equipment, ensure a placard has been installed as required by §43.11. The §91.213(d) path is the no-MEL route: §91.213(d)(3) requires the item to be deactivated and placarded INOPERATIVE, or removed and the cockpit control placarded, with the maintenance recorded.
- Maintenance entry deactivating or removing the inoperative item, with the cockpit control placarded
- INOPERATIVE placard on the affected instrument or control (or removal documented)
- Deferral / discrepancy list carrying the item until the next required inspection
- For MEL operators: the approved MEL deferral entry and category time limit instead of the §91.213(d) path
Operators flying under an approved Minimum Equipment List use the MEL's own procedures — see MEL / CDL minimum equipment list records.
Watch the §43.9 vs §43.11 distinction — it is the most common record mislabel
A repair, a part replacement, or an alteration is a §43.9 entry. An annual, 100-hour, progressive, or §135.411(a)(1)/§135.419 inspection is a §43.11 entry — and §43.9(c) expressly excludes those inspections from §43.9. Recording an annual inspection as a §43.9 maintenance entry (without the §43.11 airworthiness-determination statement and total time in service) is a real finding, because §91.405(a) requires the inspection to be performed and recorded as prescribed in subpart E and part 43, and the inspection record is §43.11.
See whether your §43.9 and §43.11 records would survive a ramp check
FileFlo classifies each entry against its governing rule and flags the mislabels and missing signatures inspectors find first.
Related Aviation Compliance Guides
§91.407 Return to Service — Who Can Sign, and the Operational-Check Flight
§91.407 is the gate between "the work is done" and "the aircraft may fly." Two records control it: the approval for return to service, and — when the work could have changed how the aircraft flies — the logged operational-check flight.
Who is authorized under §43.7 to approve return to service
Mechanic or Inspection Authorization holder
May approve return to service as provided in part 65. An IA is required to approve return to service after an annual inspection; an A&P approves after most maintenance and preventive maintenance within their privileges.
Repair station
May approve return to service as provided in part 145, within the ratings and limitations on its operations specifications.
Air carrier / air agency / operating certificate holder
May approve return to service as provided in part 121 or 135 — in a Part 135 operation, through the approved maintenance program and the personnel it authorizes.
Holder of at least a private pilot certificate
May approve return to service after performing preventive maintenance under §43.3(g) (the items listed in part 43, appendix A(c)) on an aircraft they own or operate that is not used under part 121, 129, or 135 — the authority is §43.7(f).
Full text: 14 CFR §43.7. The signer's certificate number and kind of certificate must appear in the §43.9 or §43.11 entry — that is what links the release to the §43.7 authority.
The §91.407(b) operational-check flight — when it is required, and the §91.407(c) exception
§91.407(b) triggers only when the maintenance, rebuilding, or alteration may have appreciably changed the flight characteristics or substantially affected the operation in flight. When it does, before carrying any person other than crewmembers, an appropriately rated pilot with at least a private pilot certificate must fly the aircraft, make an operational check of the work, and log the flight in the aircraft records. A major alteration that changes control rigging, adds a winglet or STC modification affecting handling, or alters the flight control system is the classic trigger.
§91.407(c) provides the off-ramp: if ground tests, inspection, or both show conclusively that the maintenance or alteration has not appreciably changed the flight characteristics or substantially affected the flight operation, the operational-check flight is not required. The decision to rely on §91.407(c) is a maintenance and airworthiness judgment — and where it is used, the conclusive ground-test or inspection results should be documented so the basis for skipping the check flight is on the record.
Releases the aircraft
- §43.7-authorized signer, with certificate number in the entry
- §43.9 (maintenance) or §43.11 (inspection) entry actually made
- Operational-check flight logged when §91.407(b) applies
- Documented conclusive ground test/inspection when relying on §91.407(c)
Does NOT release the aircraft
- Work completed but no return-to-service entry made
- Entry signed by a person without §43.7 authority for that work
- Passengers carried after handling-affecting work with no logged check flight
- Annual inspection recorded as a §43.9 entry without the §43.11 statement
For preventive maintenance an owner-pilot may perform and sign for, see aircraft preventive maintenance records under §43.3 and appendix A. For the major repair/alteration paperwork that often accompanies a §91.407(b) check flight, see FAA Form 337 major repair and alteration records and the Inspection Authorization renewal requirements for the IA whose signature releases the annual.
FileFlo as the Owner/Operator Records Layer
FileFlo is a compliance document intelligence platform — a read-only proof layer that sits alongside your maintenance tracking and your A&P's work-order system. It does not perform maintenance, hold your certificate, approve anything for return to service, or replace your IA, repair station, or maintenance program. What it does is classify, index, and surface the §43.9 entries, §43.11 inspection records, return-to-service signatures, and inoperative-equipment deferrals that prove the §91.403–§91.407 duties were discharged when an inspector asks.
- Classifies each uploaded entry against its governing reference — §43.9 maintenance vs §43.11 inspection — so the annual is never mislabeled as a repair
- Tracks the §91.409 inspection due dates (annual 12-calendar-month, 100-hour) and surfaces expiration alerts at 90/60/30 days
- Flags open inoperative-equipment deferrals carried under §91.213(d) and ties them to the next required inspection
- Confirms each return-to-service entry carries a signer name, certificate number, and kind of certificate before it is filed
- Generates an inspector-format records binder on demand — inspections, repairs, ADs, and deferrals organized so the §91.403 responsibility chain is visible at a glance
FileFlo classifies 600+ aviation document types across Part 91, Part 135, and Part 145 operators in one platform. Pricing: Starter $89/mo, Professional $299/mo. 5-day free trial, no credit card required. FileFlo does not provide or run a safety management system (SMS), dispatch, or flight operations system — it keeps the documents that prove compliance audit-ready.
Same Chain, Different Accountability — Part 91 vs Part 135
§91.403–§91.407 apply to the aircraft. What changes between a private Part 91 owner and a Part 135 certificate holder is who inside the organization owns the responsibility and how the inspection program is structured — but the documents an inspector wants to see are the same family.
Who is responsible
The registered owner, directly (§91.403)
Usually no Director of Maintenance and no maintenance department. The owner contracts an A&P/IA for work and inspections but personally carries the §91.403 airworthiness and AD-compliance responsibility. Most vulnerable to a missing return-to-service entry, an unrecorded deferral, or a mislabeled inspection record.
Who is responsible
The operator, via the DOM and approved program
The certificate holder is the operator and carries the §91.403 responsibility through its Director of Maintenance, approved inspection program, and operations specifications. Inspections may run on an approved aircraft inspection program (AAIP) or, for 10-or-more-seat aircraft, a continuous airworthiness maintenance program, reviewed by the FAA Principal Maintenance Inspector.
For how the Part 135 operator's maintenance recordkeeping is structured, see Part 135 maintenance recordkeeping and CAMP requirements and what records a Part 135 operator must keep. The person at the certificate holder who actually carries the responsibility is defined in what operational control means in Part 135.
The repair station that performs the work on either operator's aircraft owns its own §43.9 / part 145 records, but the operator keeps the §91.405/§91.417 retention obligation — see Part 145 repair station recordkeeping requirements. And no matter the part, the life-limited-part and airworthiness-limitation records from §91.403(c) travel with the aircraft for life — see life-limited parts records requirements and the aviation records retention schedule.
What It Costs When the Chain Breaks
The §91.403–§91.407 chain is enforced two ways. First, civil penalties: the FAA's penalty amounts are inflation-adjusted in 14 CFR §13.301, and for violations occurring on or after December 30, 2024 the maximum is $75,000 per violation generally, and $1,875 per violation for an individual or small business concern. Second — and far more common — grounding: an aircraft that cannot prove airworthiness from its records is treated as not airworthy until the chain is re-established.
"Records not available" is treated the same as "duty not performed"
When an inspector reviews records made available under §91.417(c) and cannot establish that an inspection was completed, an AD complied with, or the aircraft properly returned to service, the FAA cannot distinguish a documentation gap from a maintenance gap. The owner/operator under §91.403, and the person who operated the aircraft, can both face action. The completeness of the records is the defense — which is precisely why the records layer is worth getting right before an inspector ever asks.
Frequently Asked Questions
Who is legally responsible for keeping an aircraft airworthy under 14 CFR §91.403?
The owner or operator. 14 CFR §91.403(a) makes the owner or operator primarily responsible for maintaining the aircraft in an airworthy condition, including compliance with part 39 (airworthiness directives). That responsibility does not transfer to the mechanic, the repair station, or the management company that flies the aircraft. A certificated A&P or IA who signs a maintenance entry is responsible for the quality and approval of the work they personally performed and returned to service, but the continuing duty to keep the aircraft airworthy and to ensure all required inspections and ADs are accomplished sits with the owner or operator under §91.403 and §91.405. In a Part 135 operation the certificate holder is the operator and carries that responsibility through its Director of Maintenance and approved program; in a private Part 91 operation the registered owner usually carries it directly. The records are how either one proves the duty was discharged.
What is the difference between §91.403, §91.405, and §91.407?
They are three links in one chain. §91.403 (General) assigns the responsibility: the owner or operator is primarily responsible for airworthiness and for compliance with part 39, must have maintenance performed per part 43, and must not maintain or operate contrary to the airworthiness limitations section. §91.405 (Maintenance required) states the recurring duties that discharge it: have the aircraft inspected per subpart E, have discrepancies repaired per part 43, ensure a return-to-service entry is made, and address inoperative instruments and equipment (repair/replace/remove/inspect at the next required inspection, and placard per §43.11 when applicable). §91.407 (Operation after maintenance) closes the loop before flight: no operation until a person authorized under §43.7 has approved the aircraft for return to service and the §43.9 or §43.11 entry exists, plus an operational check flight by an appropriately rated pilot before carrying passengers when the work may have appreciably changed flight characteristics. Assign, perform/record, release — that is the structure.
Does §91.405 require a placard for every inoperative instrument or item of equipment?
Not for every item, but the rule is specific. 14 CFR §91.405(c) says the owner or operator shall have any inoperative instrument or item of equipment that is permitted to be inoperative by §91.213(d)(2) repaired, replaced, removed, or inspected at the next required inspection. §91.405(d) then says that when listed discrepancies include inoperative instruments or equipment, the owner or operator shall ensure that a placard has been installed as required by §43.11. The §91.213(d) path is the no-MEL route for aircraft without an approved Minimum Equipment List, and §91.213(d)(3) requires the affected item to be deactivated and placarded INOPERATIVE (or removed and the cockpit control placarded, with the maintenance recorded). The record that discharges §91.405(c)/(d) is the maintenance entry deactivating or removing the item plus the deferral list showing the item is carried as a permitted inoperative discrepancy until the next required inspection. Operators flying under an approved MEL use the MEL's own deferral and placard procedures rather than the §91.213(d) path.
What does §91.407 require before an aircraft can fly after maintenance?
Two things, and a third when flight characteristics may have changed. First, under §91.407(a) no person may operate the aircraft that has undergone maintenance, preventive maintenance, rebuilding, or alteration unless it has been approved for return to service by a person authorized under §43.7, and the maintenance record entry required by §43.9 or §43.11 has been made. Second, that approval-for-return-to-service entry is the document that legally releases the aircraft. Third, under §91.407(b), no person may carry any person other than crewmembers in an aircraft that has been maintained, rebuilt, or altered in a manner that may have appreciably changed its flight characteristics or substantially affected its operation in flight until an appropriately rated pilot with at least a private pilot certificate flies the aircraft, makes an operational check of the maintenance performed or alteration made, and logs the flight in the aircraft records. §91.407(c) lets that operational-check flight be skipped if ground tests, inspection, or both show conclusively that the maintenance or alteration has not appreciably changed the flight characteristics or substantially affected the flight operation of the aircraft.
Who is authorized under §43.7 to approve an aircraft for return to service?
14 CFR §43.7 lists the categories. The holder of a mechanic certificate or an inspection authorization may approve return to service as provided in part 65; the holder of a repair station certificate may approve it as provided in part 145; the holder of an air carrier or air agency or operating certificate may approve it as provided in part 121 or 135; and the manufacturer may approve articles it has worked on under the conditions in the section. A person holding at least a private pilot certificate may approve an aircraft for return to service after performing preventive maintenance under §43.3(g) — the items listed in part 43, appendix A(c) — on an aircraft they own or operate that is not used under part 121, 129, or 135 (the private-pilot return-to-service authority is §43.7(f), which points to §43.3(g)). There are additional provisions for light-sport aircraft repairman and sport-pilot privileges. The point for recordkeeping is that the person who signs the §43.9 entry must actually hold the authority §43.7 grants for that work, and the certificate number and kind of certificate must appear in the entry. An entry signed by someone without §43.7 authority does not release the aircraft.
What goes in the §43.9 maintenance entry that discharges §91.405(b)?
Under 14 CFR §43.9(a), each person who maintains, performs preventive maintenance, rebuilds, or alters an aircraft, airframe, aircraft engine, propeller, appliance, or component part must make an entry containing: (1) a description (or reference to data acceptable to the Administrator) of work performed; (2) the date of completion of the work performed; (3) the name of the person performing the work if other than the person specified in (a)(4); and (4) the signature, certificate number, and kind of certificate held by the person approving the work for return to service. The §43.9(a)(4) signature constitutes the approval for return to service of only the work performed. Note §43.9(c): the section does not apply to persons performing inspections under part 91, part 125, §135.411(a)(1), or §135.419 — those inspection records are governed by §43.11 instead. So a routine repair, a part replacement, or an alteration produces a §43.9 entry, while an annual or 100-hour inspection produces a §43.11 inspection entry. §91.405(b) is satisfied when the appropriate one of those entries shows the aircraft has been approved for return to service.
Does the owner have to comply with the manufacturer maintenance manual and airworthiness limitations section?
The airworthiness limitations section is mandatory, and §91.403(c)/(d) make that explicit. §91.403(c) provides that no person may maintain, preventive-maintain, or alter an aircraft for which a manufacturer maintenance manual or instructions for continued airworthiness contains an airworthiness limitations section except in accordance with that section, unless an alternative is set forth in an FAA-approved operations specification or in an inspection program approved under §91.409(e). §91.403(d) provides that a person must not alter an aircraft based on a supplemental type certificate unless the owner or operator of the aircraft is the holder of that STC or has written permission from the holder. In practical terms, the airworthiness-limitations items — life-limited part retirement times and mandatory replacement and inspection intervals — are hard limits, and the records that prove compliance with them must travel with the aircraft for its life. The rest of the manufacturer's maintenance manual is generally treated as a method of compliance and a source of data acceptable to the Administrator rather than an independent regulatory mandate, except where an inspection program or operations specification adopts it.
What are the penalties if an aircraft is operated unairworthy or without the required records?
Operating an aircraft that is not in an airworthy condition, or that has not been properly approved for return to service after maintenance, can support an enforcement action against both the owner/operator (under §91.403/§91.405/§91.407) and the person who operated it. Civil penalties under the FAA's assessment authority are inflation-adjusted in 14 CFR §13.301; for violations occurring on or after December 30, 2024, the maximum is $75,000 per violation generally, and $1,875 per violation for an individual or small business concern. Beyond civil penalty exposure, the more common practical consequence is grounding: if an inspector reviewing records under §91.417(c) cannot establish from the entries that a required inspection was completed, that an AD was complied with, or that the aircraft was properly returned to service, the aircraft is treated as not airworthy until the documentation chain can be re-established — which can mean repeating the work. The records are not paperwork for its own sake; they are the legal proof that the §91.403–§91.407 duties were met.
Prove the §91.403 chain held — before the inspector asks
FileFlo classifies each §43.9 and §43.11 entry against its governing rule, tracks §91.409 inspection due dates, flags open §91.213(d) inoperative-equipment deferrals, confirms every return-to-service signature carries a certificate number, and assembles an inspector-format records binder on demand. Starter $89/mo. Professional $299/mo. 5-day free trial — no credit card required.
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Written by Chad Griffith, Founder, FileFlo — compliance document intelligence. Reviewed June 13, 2026. FileFlo is a compliance document intelligence platform — not legal counsel, an A&P, or an airworthiness authority. Verify all airworthiness, return-to-service, and inoperative-equipment decisions with a certificated A&P, IA, or repair station and your FSDO.