{
"slug": "signatory-authority-attestation",
"topic_id": "TOPIC-139",
"cluster": "Aviation, MRO & Aerospace Airworthiness Identity",
"tier": "Tier B",
"title": "Third-country repair stations: verifying a signature across a bilateral agreement",
"summary": "Heavy maintenance concentrates offshore while oversight relies on periodic audits. An airline accepts work on the strength of a certificate number and a signature it cannot verify without an audit visit.",
"lede": "Bilateral aviation safety agreements establish that two authorities accept each other's approved organisations. They say nothing about whether the individual who signed your work package held signatory authority on the day they signed it, because nobody publishes that.",
"date": "2023-12-13",
"category": "Vertical",
"author_id": "tobias-lindqvist-rao",
"tags": [
"Part 145",
"EASA Part-145",
"bilateral agreement",
"repair station",
"certifying staff",
"vendor oversight"
],
"image_title": "Signatory Authority Attestation",
"tags_note": "",
"schema": "Article",
"key_takeaways": [
"Bilateral acceptance operates at the organisational level. Individual signatory authority is administered locally, published nowhere, and revoked silently.",
"The question that matters is not whether a person holds authority today but whether they held it on the date of the signature.",
"A signed, time-bounded signatory list lets a receiving operator verify historical authority offline, without an audit visit."
],
"body": [
{
"type": "h2",
"text": "What bilateral acceptance actually establishes"
},
{
"type": "diagram",
"kind": "chain",
"alt": "Work performed abroad, accepted at home",
"caption": "The bilateral agreement establishes mutual recognition. It does not give the receiving airline a way to test the individual signature.",
"nodes": [
{
"label": "Work performed",
"sub": "third-country station",
"note": "approved"
},
{
"label": "Release signed",
"sub": "certifying staff",
"note": "named"
},
{
"label": "Document travels",
"sub": "with the aircraft",
"note": "paper or PDF",
"bad": true
},
{
"label": "Airline accepts",
"sub": "on the certificate number",
"note": "untestable",
"bad": true
}
]
},
{
"type": "p",
"html": "A bilateral aviation safety agreement, with its maintenance implementation procedures, lets an authority accept maintenance performed by an organisation approved by the other authority. It is a system-level judgement: their oversight is comparable to ours, so their approvals are acceptable to us."
},
{
"type": "p",
"html": "Within an approved organisation, the authority to certify work is delegated to named individuals — certifying staff under EASA Part-145, authorised personnel under 14 CFR Part 145. The organisation maintains the list, assesses competence, and adds or removes people as they qualify, move on, or are withdrawn."
},
{
"type": "p",
"html": "That list is an internal document. There is no registry, no lookup service, and no obligation to publish it."
},
{
"type": "h2",
"text": "The temporal problem"
},
{
"type": "p",
"html": "The hard version of this is not is this person authorised. It is was this person authorised on 14 March 2024, asked in 2027, when the aircraft has changed operators twice and the repair station has reorganised."
},
{
"type": "table",
"head": [
"Question",
"Answerable today?",
"How"
],
"rows": [
[
"Is the organisation approved?",
"Yes",
"Authority registers are published"
],
[
"Is the approval current?",
"Yes",
"Same"
],
[
"Is this person on the certifying staff list now?",
"Only by request",
"Email the quality manager"
],
[
"Were they on it at the time of signature?",
"Rarely",
"Requires the organisation to retain and produce historical lists"
],
[
"Was their authorisation scope adequate for this work?",
"Rarely",
"Same"
]
]
},
{
"type": "p",
"html": "Rows four and five are where records reviews stall, particularly during an aircraft transition where a buyer's technical team is examining maintenance history they did not commission."
},
{
"type": "h2",
"text": "Why this is not a trust question about any country"
},
{
"type": "p",
"html": "It is worth being explicit, because this topic attracts unhelpful framing. The gap is structural and identical for a repair station in Texas and one in Singapore. Nothing about offshore maintenance is inherently less reliable; the issue is that individual signatory authority is invisible to relying parties everywhere, and offshore simply makes the audit-visit remedy more expensive."
},
{
"type": "h2",
"text": "The Signatory Authority Attestation"
},
{
"type": "p",
"html": "The repair station publishes, periodically, a signed list: individual identifiers, authorisation scope, valid-from and valid-until. Nothing about the list is novel except that it is signed and retained."
},
{
"type": "code",
"text": "{\n \"type\": \"manav-stmt/1\",\n \"action\": \"certifying_staff_authorisation\",\n \"organisation\": \"[approval reference]\",\n \"effective\": \"[from]–[to]\",\n \"staff\": [\n { \"id\": \"[auth number]\", \"credential\": \"[public key]\",\n \"scope\": \"[ratings / aircraft types / limitations]\" }\n ],\n \"signed_by\": \"[accountable manager or quality manager]\"\n}"
},
{
"type": "p",
"html": "A release signed by an individual then verifies twice: the signature is valid for that credential, and that credential appears in a signed staff list whose validity window covers the signature date. Both checks are offline."
},
{
"type": "h2",
"text": "What this changes operationally"
},
{
"type": "ul",
"items": [
"Records review during aircraft transition stops requiring correspondence with every repair station in the history.",
"Vendor audits can sample against published lists rather than requesting them, which shortens the on-site portion.",
"A repair station whose authority was withdrawn from an individual can demonstrate the withdrawal date, which protects the station as much as the customer.",
"A lessor's technical acceptance becomes a verification rather than a negotiation."
]
},
{
"type": "h2",
"text": "The privacy consideration"
},
{
"type": "p",
"html": "A published staff list is personal data. Publish authorisation numbers and scopes, not names and not personal details. The authorisation number is the identifier the regulatory framework already uses, and it is sufficient for verification without turning a compliance artefact into a directory of individuals."
},
{
"type": "h2",
"text": "Adoption, realistically"
},
{
"type": "p",
"html": "This has a network property and should be framed honestly. One repair station publishing signed staff lists benefits only its own customers, which is enough to start but not enough to claim ecosystem value."
},
{
"type": "p",
"html": "The realistic sequence is that a large operator requires it of its top five heavy maintenance vendors as a contractual term, those vendors find it reduces audit days, and the practice spreads through the vendors' other customers. That is how every verifiable-document scheme in aviation has actually propagated."
},
{
"type": "h2",
"text": "What mutual recognition does and does not give you"
},
{
"type": "table",
"caption": "Layers of assurance",
"head": [
"Layer",
"Provided by",
"Testable per release?"
],
"rows": [
[
"Organisation approval",
"The bilateral agreement and the authority",
"No — periodic"
],
[
"Scope of approval",
"The certificate",
"Partly"
],
[
"Individual certifying authority",
"The organisation's internal system",
"No"
],
[
"This specific release",
"The document",
"No"
]
]
},
{
"type": "h2",
"text": "Objections and honest limits"
},
{
"type": "p",
"html": "“The authority audits the station.” Periodically, and for the organisation. Neither of those tells the receiving airline whether this individual held certifying authority on this date for this scope."
},
{
"type": "p",
"html": "“We could require more paperwork.” More paperwork is more of the same artefact. The change is making one artefact testable rather than adding another that is not."
}
],
"faq": [
{
"q": "Does this replace vendor audits?",
"a": "No. Audits assess capability, tooling, training and culture. This addresses one narrow question that audits currently answer only by sampling."
},
{
"q": "Who signs the staff list?",
"a": "The accountable manager or quality manager, using a credential under their sole control. The list is an organisational assertion about individuals."
},
{
"q": "What if a station cannot produce historical lists?",
"a": "Then the temporal question is unanswerable for work already performed. This changes the position going forward; it cannot repair history."
},
{
"q": "Is this acceptable to authorities?",
"a": "It is additive. Regulatory acceptance of the release document is unchanged; this is assurance the receiving operator performs for itself."
},
{
"q": "What does a bilateral agreement actually give the receiving airline?",
"a": "Mutual recognition of organisational approvals. It does not make an individual release testable."
},
{
"q": "What is the missing check?",
"a": "Whether the named individual held certifying authority, for that scope, on that date."
},
{
"q": "Why does ten-year verifiability matter?",
"a": "Because the record follows the aircraft, and outlives the contract and often the station."
}
],
"sources": [
{
"t": "FAA — aircraft repair and bilateral agreement resources",
"u": "https://www.faa.gov/aircraft/repair"
},
{
"t": "EASA — document library and safety publications",
"u": "https://www.easa.europa.eu/en/document-library"
},
{
"t": "Industry practice guidance on aircraft records review during transition."
},
{
"t": "FAA — regulations and policies",
"u": "https://www.faa.gov/regulations_policies"
}
],
"related": [
{
"slug": "rts-signature-uniqueness-test",
"title": "Unique to one individual",
"category": "Vertical"
},
{
"slug": "release-certificate-receipt",
"title": "625 stolen engine parts and a paper tag",
"category": "Vertical"
},
{
"slug": "aviation-correction-chain",
"title": "The FAA expanded its falsification rule",
"category": "Vertical"
}
],
"image": "https://cdn.twc.sh/images/igcache/Signatory%20Authority%20Attestation/1200_630/blog.jpg",
"wordcount": 907,
"url": "/blog/signatory-authority-attestation.html",
"reading_time": "4 min read",
"seo_title": "Verifying repair station signatures across borders",
"meta_description": "Heavy maintenance concentrates offshore while oversight is periodic audit. An airline accepts work on a certificate number and a signature block.",
"hub": {
"slug": "topics/airworthiness-identity",
"title": "Aviation and airworthiness identity"
},
"answer": "Today, by trusting a certificate number and a signature block. Heavy maintenance concentrates offshore while oversight relies on periodic audits, so an airline accepting work across a bilateral agreement is accepting a document it cannot test against the issuing authority.",
"answer_q": "How do you verify a repair station signature across a bilateral agreement?",
"glossary": [
{
"term": "Bilateral agreement",
"def": "An arrangement under which two authorities recognise each other's approvals, with maintenance implementation procedures defining the detail."
},
{
"term": "Certifying staff",
"def": "Individuals authorised by an approved organisation to issue releases within a defined scope."
},
{
"term": "Scope of approval",
"def": "The work an organisation is approved to perform. A release outside scope is not a valid release."
}
],
"checklist": {
"title": "Testing a third-country release",
"id": "test",
"desc": "Four questions.",
"steps": [
{
"name": "Can you test the individual's certifying authority?",
"text": "Not the organisation's approval — the individual's, on that date."
},
{
"name": "Can you test the scope?",
"text": "That the work performed was inside the approval."
},
{
"name": "Can you test it without contacting the station?",
"text": "Verification that requires the counterparty is verification you will skip."
},
{
"name": "Will it still verify in ten years?",
"text": "Which is the aircraft's timescale, not the contract's."
}
]
},
"cta": {
"title": "Where this fits in Manav",
"html": "Manav binds an airworthiness or operational signature to the exact record it certifies, on a credential under one individual's sole control, and produces a receipt an auditor or a regulator can verify years later without access to the operator's systems.",
"href": "../docs.html",
"label": "See signature binding"
}
}