The Short Answer
14 CFR §145.221 requires a certificated repair station to report to the FAA, within 96 hours after it discovers any serious failure, malfunction, or defect of an article, in a format acceptable to the FAA. The report must include as much of seven listed data points as is available — aircraft registration number, type/make/model of the article, date of discovery, nature of the defect, time since last overhaul (if applicable), apparent cause, and any other pertinent information. This is the repair station’s own reporting duty, and it is separate from the service difficulty report a Part 135 operator files under §135.415.
§145.221 also has built-in anti-duplication rules: a shop that already reported the same defect under parts 21, 121, 125, or 135 need not report it again under §145.221(c), and a shop may file the report on behalf of a Part 121/125/135 certificate holder under §145.221(d) — but must then forward a copy to that certificate holder and may not report the same defect again under paragraph (a) (§145.221(e)). FileFlo does not file the report; it keeps the work order, inspection, and release records behind the report audit-ready.
Most repair stations know the airframe and powerplant work cold. Fewer have a tight handle on the reporting obligation that attaches when the shop finds something serious on an article — the 96-hour service difficulty report under 14 CFR §145.221. This article decodes the rule paragraph by paragraph, walks through the seven required fields, untangles the no-double-reporting logic, and draws the bright line between the §145.221 repair station report and the §135.415 operator report that compliance teams routinely confuse.
For the broader recordkeeping picture, this post pairs with FileFlo’s deep dives on Part 145 repair station recordkeeping (§145.219) and the Part 135 service difficulty report (§135.415). Read those for each side of the reporting chain; read on here for the repair station’s specific 96-hour duty.
The clock starts at discovery — not at work-order close
The single most common §145.221 trap is treating the report as a back-office task that happens when the job closes. The 96-hour window runs from the moment the shop discovers the serious failure, malfunction, or defect (§145.221(b)(3) even makes the date of discovery a required report field). A defect found Friday afternoon can put the deadline inside the weekend — build the trigger into the inspection workflow, not the billing workflow.
14 CFR §145.221 Decoded: Every Paragraph
The rule runs from paragraph (a) through (e). Paragraphs (a) and (b) set the duty and its contents; (c) prevents duplicate reporting; (d) and (e) handle filing on behalf of an air carrier. Here is what each paragraph actually requires.
The 96-hour reporting duty
"A certificated repair station must report to the FAA within 96 hours after it discovers any serious failure, malfunction, or defect of an article. The report must be in a format acceptable to the FAA."
Three triggers, all required to be met
The duty fires when (a) the repair station (b) discovers (c) a serious failure, malfunction, or defect of an article. "Discovers" is the timing word — the 96-hour clock starts then. "Serious" is the threshold word — a routine, expected wear finding within limits is not, by itself, a §145.221 event. The rule does not enumerate serious conditions for repair stations the way §135.415 lists specific operational events, so the seriousness call is a documented inspection judgment.
"Format acceptable to the FAA"
The rule does not bolt the report to a single form number in its text. In practice the FAA collects service difficulty data through its Service Difficulty Reporting System, and a repair station should confirm the current accepted submission method with its responsible Flight Standards office. The compliance point: the report must reach the FAA, in a form the FAA accepts, within the window — the seriousness judgment and the filing method are both the repair station’s responsibility.
Common §145.221(a) failure mode
A serious defect is found and corrected on the article, the work is documented perfectly — but the separate service difficulty report to the FAA is never filed, or is filed outside the 96-hour window. Excellent maintenance does not satisfy the reporting duty; they are two different obligations.
What the report must contain
"The report required under paragraph (a) of this section must include as much of the following information as is available: (1) Aircraft registration number; (2) Type, make, and model of the article; (3) Date of the discovery of the failure, malfunction, or defect; (4) Nature of the failure, malfunction, or defect; (5) Time since last overhaul, if applicable; (6) Apparent cause of the failure, malfunction, or defect; and (7) Other pertinent information that is necessary for more complete identification, determination of seriousness, or corrective action."
The qualifier "as much of the following information as is available" is doing real work. It means a missing data point does not stop the clock — you file what you have inside 96 hours rather than holding the report while you chase, say, the exact time since last overhaul. The seven fields are walked through individually in the next section. Note that field (3), the date of discovery, is also the date that starts the §145.221(a) clock, so it should never be the field you are missing.
The no-duplicate-reporting exception
"The holder of a repair station certificate that is also the holder of a part 121, 125, or 135 certificate; type certificate (including a supplemental type certificate); parts manufacturer approval; or technical standard order authorization, or that is the licensee of a type certificate holder, does not need to report a failure, malfunction, or defect under this section if the failure, malfunction, or defect has been reported under parts 21, 121, 125, or 135 of this chapter."
§145.221(c) exists because one organization can wear several FAA hats at once — a repair station that is also a Part 135 air carrier, or a TC/STC/PMA/TSO holder. Without this paragraph, the same defect could trigger reporting duties under two or three parts simultaneously. The exception is narrow and conditional:
Who it covers
A repair station that ALSO holds a Part 121/125/135 certificate, a type certificate (including an STC), a PMA, or a TSO authorization — or is the licensee of a TC holder.
The condition
The relief applies ONLY if that same failure, malfunction, or defect has actually been reported under parts 21, 121, 125, or 135. No other report filed means no exception — the §145.221(a) duty stands.
The trap: a shop assumes "the operator will report it" and skips its own §145.221 filing — but the operator either was not obligated to report under §135.415 for that condition, or never did. The exception protects you only when the other report was actually filed. Confirm it; do not assume it.
Filing on behalf of an air carrier — and the copy back
"(d) A certificated repair station may submit a service difficulty report for the following: (1) A part 121 certificate holder, provided the report meets the requirements of part 121 of this chapter, as appropriate. (2) A part 125 certificate holder, provided the report meets the requirements of part 125 of this chapter, as appropriate. (3) A part 135 certificate holder, provided the report meets the requirements of part 135 of the chapter, as appropriate. (e) A certificated repair station authorized to report a failure, malfunction, or defect under paragraph (d) of this section must not report the same failure, malfunction, or defect under paragraph (a) of this section. A copy of the report submitted under paragraph (d) of this section must be forwarded to the certificate holder."
The report has to meet the OPERATOR’s rule, not the shop’s
When a contract maintenance shop files for a Part 135 operator under §145.221(d)(3), the report must meet the requirements of Part 135 — i.e., the §135.415 content and process — "as appropriate," not merely the §145.221 fields. A shop that files an operator’s report on a §145.221 template can leave the operator short of its own §135.415 obligation. This is a coordination detail worth pinning down in the maintenance contract.
Two hard rules in paragraph (e)
First, no double reporting: a shop that files under (d) must not also report the same defect under (a). Second — and this is the most-missed obligation in the whole section — a copy of the report submitted under (d) must be forwarded to the certificate holder. The operator needs that copy for its own records and to know the report on its aircraft was made. A filed report with no copy back to the operator is a §145.221(e) gap even when the FAA got its report.
Document the copy-back, not just the filing
Because §145.221(e) requires forwarding a copy to the certificate holder, keep evidence that the copy went out — a transmittal email, a logged delivery, or a countersigned receipt. When an inspector reviews a report the shop filed on an operator’s behalf, "we filed it" answers half the question; "and here is the copy we sent the operator" answers the rest.
The Seven §145.221(b) Report Fields
Every §145.221 service difficulty report must include as much of these seven data points as is available. Treat them as a checklist the inspection team completes the moment a serious finding is logged — the report is far easier to file inside 96 hours when the fields are captured at discovery.
Aircraft registration number
The N-number of the aircraft the article came from, where applicable. Ties the defect back to a specific airframe in the FAA’s data.
Type, make, and model of the article
Identifies the component, accessory, or part involved — engine, propeller, landing gear assembly, avionics unit, structural element, etc.
Date of the discovery of the failure, malfunction, or defect
The date the shop found the condition. This is also the date that starts the 96-hour reporting clock under §145.221(a).
Nature of the failure, malfunction, or defect
A description of what was actually wrong — the crack, corrosion, wear beyond limits, improper prior repair, or component condition discovered.
Time since last overhaul, if applicable
Where the article is tracked on a time-since-overhaul basis, the hours/cycles since its last overhaul. The "if applicable" qualifier is in the rule.
Apparent cause of the failure, malfunction, or defect
The shop’s best assessment of why the condition occurred — fatigue, improper installation, environmental, manufacturing, prior maintenance, etc.
Other pertinent information for identification, seriousness, or corrective action
Any additional detail necessary for more complete identification, determination of seriousness, or corrective action — the catch-all that lets the FAA act on the report.
Why capture at discovery: fields like time since last overhaul (5) and apparent cause (6) are easy to record while the article is open on the bench and hard to reconstruct days later. The rule lets you file with what you have, but a report missing several fields invites FAA follow-up — and follow-up is friction you can avoid by building the seven-field capture into the receiving inspection and teardown steps.
Related: Part 145 & FAA Reporting Compliance
§145.221 vs. §135.415: Two SDRs, Two Certificate Holders
"Service difficulty report" appears in both Part 145 and Part 135, and the two are routinely conflated. They are distinct duties on distinct certificate holders, with different scopes and different content rules — and a single defect can implicate both. Here is the side-by-side.
When the same defect touches both rules
Picture a Part 135 operator whose contract maintenance shop (a Part 145 repair station) finds a serious structural crack during a check. The operator may have a §135.415 reporting obligation for the condition; the shop has a §145.221 reporting obligation as the entity that discovered it on the article. §145.221 is engineered to resolve the overlap: the shop can file on the operator’s behalf under (d) — meeting Part 135’s requirements and forwarding a copy to the operator under (e) — or the operator files under §135.415 and the shop’s §145.221(c) relief applies because the defect was reported under Part 135. What you cannot do is leave a gap where each party assumed the other reported it.
For the operator side of this chain, see Part 135 service difficulty reports (§135.415), Part 135 contract maintenance records, and mechanical irregularity and discrepancy records (§135.65).
The Records Behind the Report (§145.219)
§145.221 produces the report; §145.219 governs the supporting records. When an FSDO inspector or an NTSB investigator pulls the thread on a service difficulty report, the documents that prove what the article was and what was found come from the repair station’s recordkeeping system. Here is how the two rules connect.
The work order supplies the report’s facts
Several §145.221(b) fields — type/make/model of the article, nature of the defect, apparent cause, time since last overhaul — come straight off the work order and the teardown findings. A work order that meets the 14 CFR §43.9 content standard makes the SDR fields easy to populate; a thin work order leaves the report under-documented. See our §43.9 maintenance entry breakdown.
Traceability proves which article the defect was on
The receiving inspection record and the release documentation (the maintenance release, or an FAA Form 8130-3 where used) tie the reported defect to a specific part by part number and serial number. If an investigator asks "which exact unit had this defect," the answer lives in the traceability chain covered by §145.219 recordkeeping and 8130-3 parts traceability.
Retention: 2-year floor under §145.219(c), longer in practice
§145.219(c) requires retaining the records required by that section for at least 2 years from the date the article was approved for return to service, and §145.219(d) requires them to be available for inspection by the FAA and the NTSB. Because an SDR can resurface years later — in a fleet-wide AD investigation, an accident probe, or a recurring-defect trend — the supporting records behind a report are the last thing a prudent shop discards at the 2-year minimum.
The copy-back document (when you filed for an operator)
If the shop filed under §145.221(d), the copy forwarded to the certificate holder under §145.221(e) is itself a record worth keeping — proof the operator received the report on its aircraft. Pair it with the contract maintenance documentation so the whole on-behalf-of arrangement is provable end to end.
How §145.221 connects to the rest of the maintenance-records web
A service difficulty report rarely stands alone. The same finding can drive an airworthiness directive compliance record, a Form 337 if the corrective action is a major repair or alteration, an entry against the life-limited parts record if a life limit is involved, and — for the operator — an irregularity/discrepancy record under §135.65. The report is a node in a mesh of records, which is exactly why a defect that is reported well but documented poorly still creates exposure.
Where a Document Intelligence Platform Fits in §145.221 Compliance
FileFlo is a compliance document intelligence platform — a read-only proof layer that sits alongside the maintenance stack and makes the records you already have audit-ready. It does not file your service difficulty reports with the FAA, perform maintenance, or make the airworthiness judgment about whether a defect is "serious." Those are the repair station’s responsibilities. FileFlo handles the document layer those duties leave exposed.
Specifically for §145.221, FileFlo classifies the documents that surround a report (work orders, receiving inspection records, 8130-3 tags, the report copy forwarded to the certificate holder), links them by part and serial number so the SDR’s subject article is traceable on one screen, tracks the §145.219(c) 2-year retention clock per article, and flags the §145.221(e) copy-back obligation when a report is filed on an operator’s behalf. When an inspector or investigator asks for the records behind a report, the packet assembles in seconds instead of a day of binder-building.
Report-package classification
Upload the work order, inspection record, and release documents tied to an SDR — FileFlo classifies each against the correct CFR section and groups them as the supporting package for the report.
Traceability cross-reference
The reported article is linked to its receiving inspection and release documentation by part number and serial number, so "which exact unit" is answerable instantly.
Retention clock (§145.219(c))
Per-article retention clocks run from the return-to-service approval date; SDR-supporting records approaching the 2-year floor surface in the 90/60/30-day alert queue.
Copy-back tracking (§145.221(e))
When a report is filed on a Part 121/125/135 operator’s behalf, FileFlo surfaces the obligation to forward a copy to the certificate holder and keeps the transmittal as a record.
FileFlo does not file service difficulty reports, run maintenance, or replace a Safety Management System (SMS), dispatch/FOS, or your quality control system. The repair station files the §145.221 report through the FAA’s accepted method and makes the seriousness judgment. FileFlo keeps the documents that prove the report and its supporting records exist — audit-ready, at the moment the inspector asks.
Pricing: Starter $89/month, Professional $299/month. 5-day free trial, no credit card required. Learn more at FileFlo for Part 145 Repair Stations.
Can you produce the records behind every report you filed?
FileFlo’s FAA readiness score reviews your record documentation — work orders, inspection records, 8130-3 traceability, and the report copies forwarded to certificate holders — and shows you the gaps an FSDO inspector would likely cite before the surveillance visit. Takes under 10 minutes.
Check Your FAA Readiness Score — FreeFrequently Asked Questions
What does 14 CFR §145.221 require a repair station to report, and how fast?
14 CFR §145.221(a) requires a certificated repair station to report to the FAA within 96 hours after it discovers any serious failure, malfunction, or defect of an article. The report must be in a format acceptable to the FAA. The 96-hour clock starts at discovery — not at the date the article was received, not when the work order is closed, and not when a manager reviews it. This is the repair station holder’s own reporting duty under Part 145, and it is distinct from the air-carrier service difficulty report a Part 135 certificate holder files under §135.415.
What information has to be in a §145.221 service difficulty report?
Under §145.221(b), the report must include as much of the following as is available: (1) aircraft registration number; (2) type, make, and model of the article; (3) date of the discovery of the failure, malfunction, or defect; (4) nature of the failure, malfunction, or defect; (5) time since last overhaul, if applicable; (6) apparent cause of the failure, malfunction, or defect; and (7) other pertinent information that is necessary for more complete identification, determination of seriousness, or corrective action. The rule says "as much of the following information as is available," so a missing data point does not excuse late filing — you report what you have within 96 hours and supplement later if needed.
How is the §145.221 repair station SDR different from the §135.415 air-carrier SDR?
They are two separate reporting duties that sit on two different certificate holders. §135.415 is the service difficulty report a Part 135 certificate holder files for its own fleet when a listed failure, malfunction, or defect occurs in operation — that report covers each 24-hour period and is submitted to the collection point within the next 96 hours. §145.221 is the repair station holder’s duty: when the shop discovers a serious failure, malfunction, or defect of an article it is working on, it reports to the FAA within 96 hours. The same physical defect can therefore touch two regimes — the operator’s §135.415 report and the repair station’s §145.221 report — but §145.221 contains built-in coordination rules so the same event is not double-reported. See our companion posts on the Part 135 SDR and Part 145 recordkeeping for each side.
When does a repair station NOT have to file a §145.221 report?
Under §145.221(c), a repair station that also holds a Part 121, 125, or 135 certificate; a type certificate (including a supplemental type certificate); a parts manufacturer approval; or a technical standard order authorization — or that is the licensee of a type certificate holder — does not need to report a failure, malfunction, or defect under §145.221 if that same failure, malfunction, or defect has already been reported under parts 21, 121, 125, or 135. The intent is to avoid duplicate filings for a single event. Separately, §145.221(e) prohibits a repair station that submits a report on a certificate holder’s behalf under paragraph (d) from also reporting the same defect under paragraph (a).
Can a Part 145 repair station file the service difficulty report on behalf of a Part 135 operator?
Yes. §145.221(d) lets a certificated repair station submit a service difficulty report for a Part 121, 125, or 135 certificate holder, provided the report meets the requirements of that part. If the shop files on behalf of a Part 135 operator, the report has to satisfy Part 135’s requirements, not just Part 145’s. Critically, §145.221(e) then requires the repair station to forward a copy of that report to the certificate holder, and it bars the shop from reporting the same failure, malfunction, or defect again under §145.221(a). This is a common arrangement where a contract maintenance shop handles the reporting for an operator’s aircraft, but the paper trail — the copy back to the certificate holder — is the part most often missed.
How long does a repair station keep the service difficulty report and its supporting records?
The service difficulty report itself is filed with the FAA, but the records that support it — the work order, receiving inspection record, and release documentation that establish what the article was and what was found — fall under the Part 145 recordkeeping rule. §145.219(c) requires a certificated repair station to retain the records required by that section for at least 2 years from the date the article was approved for return to service, and §145.219(d) requires those records to be available for inspection by the FAA and the National Transportation Safety Board. Because an SDR can become the thread an investigator pulls during a surveillance visit or an accident investigation, most shops keep the SDR and its supporting documents well beyond the 2-year floor.
What is a "serious" failure, malfunction, or defect for §145.221 purposes?
The rule uses the word "serious" but §145.221 does not enumerate a list of qualifying conditions the way the Part 135 operator rule (§135.415) lists specific events such as in-flight fires, engine shutdowns, and structural cracks. For the repair station, seriousness is a judgment a qualified inspector makes about a defect discovered on an article — a crack, corrosion, improper prior repair, or component condition that could affect airworthiness or safe operation. Because the determination is judgment-based, shops should document why a finding was or was not treated as serious, so the decision is defensible if the FAA later questions whether a §145.221 report should have been filed.
Is FileFlo a substitute for filing the §145.221 report with the FAA?
No. FileFlo is a compliance document intelligence platform — a read-only proof layer. It does not file service difficulty reports with the FAA, perform maintenance, or make the airworthiness judgment about whether a defect is "serious." What it does is keep the documentation around the report audit-ready: it classifies the work order, receiving inspection record, and release documents tied to an SDR, links them by part and serial number, tracks the §145.219 retention clock, and surfaces the copy-back-to-certificate-holder obligation when a report is filed on an operator’s behalf. The actual report is filed by the repair station through the FAA’s accepted method; FileFlo proves the supporting records exist when an inspector asks.
More Aviation Compliance Resources
Part 135 Service Difficulty Reports (§135.415)
The air-carrier SDR — the operator side of the reporting chain
Part 145 Repair Station Recordkeeping (§145.219)
2-year retention · §43.9 work orders · 8130-3 traceability
Part 145 Audit Binder: What Inspectors Ask For
How an FSDO surveillance records review actually proceeds
14 CFR §43.9 — Maintenance Record Entries
The four-element content standard behind the report fields
Airworthiness Directive Compliance Records
14 CFR Part 39 · how an SDR can drive an AD record
FAA Form 337 — Major Repair & Alteration Records
When the corrective action is a major repair or alteration
Part 135 Contract Maintenance Records
The on-behalf-of arrangement under §145.221(d)
What Records Must a Part 135 Operator Keep?
The full operator recordkeeping picture
Know where your §145.221 documentation stands before the inspector does
FileFlo’s FAA readiness score reviews the records behind every service difficulty report — work orders, receiving inspection records, 8130-3 traceability, retention clocks, and the report copies forwarded to certificate holders. Takes under 10 minutes. No credit card required.
5-day free trial · No credit card required · Starter $89/mo · Professional $299/mo