AC 120-78B, in Plain English: What Makes an Electronic Signature FAA-Compliant
FAA Advisory Circular 120-78B covers the acceptance and use of electronic signatures, electronic recordkeeping, and electronic manuals. If your repair station wants to stop printing work orders just to sign them, this is the document your inspector will measure you against. Here is what it means without the legalese.
The five things an electronic signature must prove
- Attribution: who signed. The signature must uniquely identify one person. Shared logins, generic accounts, and "the front desk clicks approve for everyone" all fail here.
- Intent: they meant to sign. Signing must be a deliberate act, distinct from just saving a form. A re-authentication step (re-entering a password or PIN at the moment of signing) is the cleanest way to show it.
- Non-repudiation: they can't deny it later. The system must keep evidence connecting the person to the signature: who, when, from where, tied to their credentials.
- Record integrity: nothing changed after signing. Once signed, the record must be protected from alteration, and any alteration must be detectable. Cryptographic hashes (like SHA-256) stored with the signed record are the standard approach.
- Traceability: a complete audit trail. Every signing event logged, retrievable, and attached to the signed document for the life of the record.
Common ways shops get this wrong
- A picture of an ink signature pasted into a PDF. That is an image, not a signature. It has no attribution, no intent, and no integrity.
- Signing in a system where records stay editable. If a discrepancy can be reworded after the CRS signs the release, the signature protects nothing.
- One tablet, one login, whole shop. Convenient, and completely non-attributable.
- No signature levels. The tech performing work, the inspector approving it, and the person returning the aircraft to service are different acts by different authorities. A single "done" checkbox flattens the accountability your manual promises the FAA.
What a compliant workflow looks like in practice
In Orion, each discrepancy is signed by the technician, locked at the LBE sign-and-lock stage, and released via CRS signature. That is three distinct levels, each requiring the signer to re-enter their credentials at the moment of signing. The instant a record is signed, a SHA-256 hash is computed and stored; any later tampering breaks the hash visibly. Every event lands in a nonrepudiation log, and the signature (with certificate number) is embedded in every printed layout, so the paper your customer receives matches the electronic record the inspector sees.
The electronic recordkeeping side of AC 120-78B
The advisory circular covers more than the signature itself. It also describes acceptable electronic recordkeeping: the signed record has to remain complete, retrievable, and protected for its whole retention life, with any alteration detectable. In practice that means the system storing your work orders and logbook entries matters as much as the signing ceremony. A compliant signature saved into an editable file system is a contradiction. Orion stores signed records hash-locked in the same system that created them, with the audit trail attached, so retrieval for an inspector is a search rather than a folder hunt.
Looking for an FAA electronic signature template?
A lot of people search for an FAA electronic signature template, and it is worth saying plainly: there is no template that makes a signature compliant, because AC 120-78B describes system behavior, not a form layout. A template can give you a signature block with a name, certificate number, and date, and you should have that. But attribution, intent, tamper evidence, and the audit trail are properties of the software capturing the signature, not of the document design. If someone can open the file afterward and change what was signed, no template saves it. The five requirements above are the real checklist; bring them to whatever system you evaluate.
Considering the move from wet ink? Our post on going from paper to digital maintenance records covers the transition, or schedule a call to see the three-level signature flow on a live work order.