Type Certificate Data Sheets, Supplemental Type Certificates, and FAA-Approved Data

What Is a Type Certificate Data Sheet?

When the FAA issues a Type Certificate (TC) for an aircraft, engine, or propeller, it records the approved design specifications on a Type Certificate Data Sheet (TCDS). The TCDS is the definitive, legally binding summary of what the manufacturer was approved to build. You can think of it as the aircraft's "birth certificate" combined with its operating rules. Every certificated aircraft in the United States has a TCDS, and the current revision is always available free of charge at the FAA aircraft certification database (rgl.faa.gov).

A TCDS contains, among other items:

• Model designation and category (normal, utility, acrobatic, transport, etc.)
• Engine make, model, and horsepower — including every approved engine alternative
• Approved propeller combinations
• Fuel grades approved for use
• Operating limitations — airspeed limits, maximum weights, temperature limits, and more
• Center-of-gravity (CG) range at various weight conditions
• Datum location used for weight-and-balance computations
• Minimum flight crew
• Maximum passenger seating
• Required equipment and any placard requirements
• Serial number applicability — which serial numbers the data covers

The TCDS is issued under the authority of 14 CFR Part 21 and is part of the Type Certificate itself. When you work on a certificated aircraft, the TCDS tells you what is approved by design. Installing anything that deviates from the TCDS without proper authorization is a regulatory violation.

Reading and Using the TCDS

TCDS documents are organized into numbered sections. Revisions are identified by a revision letter or number at the top of the document. When two revisions are compared, the differences reveal approved changes to the design — a new engine alternative added, an airspeed limit clarified, or a serial-number range added for a variant model.

As an aviation maintenance technician, you will consult the TCDS to:

1. Confirm the aircraft's approved engine and propeller combination before performing engine-related work.

2. Verify approved fuel grades — using an unapproved fuel grade is an airworthiness violation.

3. Confirm weight-and-balance datum and CG envelope when updating weight-and-balance records.

4. Identify required placards and equipment that must be present for the aircraft to be airworthy.

Engine Time Between Overhaul (TBO): Note that TBO is not usually listed in the TCDS for general aviation piston engines. TBO for those engines is typically found in the engine manufacturer's service manual or service bulletin. Knowing where TBO comes from — and that it is not in the TCDS — is a common knowledge check.

Supplemental Type Certificates

A Supplemental Type Certificate (STC) is FAA approval for a modification that changes the original type design. If someone wants to install an engine not listed in the TCDS, add a glass-panel avionics suite, or convert a piston aircraft to turbine power, they must obtain an STC. The STC holder has demonstrated to the FAA that the modification meets applicable airworthiness standards.

An STC does not replace the TCDS — it supplements it. The aircraft still operates under its original TCDS plus the STC data. When an STC is installed:

• The STC approval document must be in the aircraft records.
• The STC installation instructions (Instructions for Continued Airworthiness, or ICA, if applicable) must be followed exactly during installation.
• An Aircraft Flight Manual Supplement (AFMS) is typically required and must be kept in the aircraft with the Pilot's Operating Handbook (POH) or AFM.
• A maintenance entry must be made in the aircraft logbook, referencing the STC number and describing the work performed.
• A new weight-and-balance report is required whenever the modification changes the aircraft's empty weight or CG.

The STC number itself (format: SA followed by digits and a location identifier) ties all this paperwork together. Inspectors and technicians must be able to locate every required document during records review.

FAA-Approved Data and Your Responsibility

"FAA-approved data" is a phrase you will use throughout your career. It refers to data that the FAA has specifically approved for use in maintenance and alteration, including TCDS information, STC data packages, FAA-approved Airplane Flight Manuals, and certain manufacturer's maintenance manuals when designated as FAA-approved. Not all manufacturer publications carry this designation automatically — the cover page or a specific statement in the document will indicate FAA approval.

Using unapproved data to perform a major repair or major alteration is a regulatory violation and can ground an aircraft, cost a technician their certificate, and — most importantly — compromise safety.

Safety Considerations

Data errors have caused accidents. Before beginning any modification or repair:

• Confirm you have the current revision of the TCDS or STC.
• Never work from a photocopied or handwritten summary of a TCDS — always go to the source document.
• When in doubt about applicability (serial numbers, model variants), stop and research before acting.
• Keep all STC documentation physically in the aircraft; a modification without its paperwork is treated as an unapproved alteration during an airworthiness inspection.
• PPE applies during any installation work: eye protection when working with avionics wiring, hearing protection near running engines, and general shop safety whenever tools and hardware are involved.