Approved Data. Technical data that was examined and approved (for major repairs and alterations) through applicable FAA authority, or previously approved documents such as FAA-approved manufacturers service bulletins. This includes: type certificate data sheets (TCDS), supplemental type certificates (STC), Airworthiness Directives, Manufacturers FAA-approved data, Designated Engineering Representative (DER)-approved data, and Designated Alteration Station (DAS)-approved data developed for alterations performed by that station only.
Acceptable Data. Technical data that was examined and accepted by the FAA. It is used for minor or routine maintenance, repairs, or alterations. Data that may be used on an individual basis to obtain approval are ACs, manufacturers technical information (e.g., manuals, bulletins, kits, and so forth), Military Specifications, and FAA field approvals.
What is technical data. It is drawings and specifications, including a list of drawings and specifications, needed to define the configuration and design features of a particular article, repair, or alteration. Typically, this includes information on materials, dimensions, and processes necessary to define structural strength, any required airworthiness limitations, and any data necessary to determine the airworthiness, noise characteristics, fuel venting, and exhaust emissions (as applicable) of the altered or repaired aircraft. Technical data also includes test data and engineering analyses and other engineering information, such as engineering handbooks or approved military or industry specifications. It may also include operational and service experience, maintenance and alteration experience, reliability data, and other documented factual information that can be shown to be directly applicable to the airworthiness of the article. (Reference Part 21, section 21.31.)
Under 14 CFR Parts 65, 121, 135, and 145, maintenance providers are responsible for obtaining FAA approval of technical data prior to approving a major repair or major alteration for return to service. Sometimes, manufacturers elect to obtain the FAA's approval of technical data supporting a maintenance or alteration action before issuing a service document. This is often the most efficient and cost-effective way to approve technical data because it eliminates the need for affected operators and maintenance providers to secure independent approval before doing the work. However, it remains the operator's responsibility to ensure that the Administrator's approval of technical data is obtained, if required, before approving for return to service a repair or alteration based on the advice or recommendation of a manufacturer. A No Technical Objection (NTO) letter or a statement that a particular maintenance or alteration action is "DER approvable" does not constitute FAA approval. However, such a statement may be considered, when supported along with other technical information, when evaluating the airworthiness of a particular maintenance or alteration action or continue-in-service condition.
When a manufacturer has obtained the FAA's approval of technical data, a service document is often marked "FAA-Approved," "FAA/DER-Approved," or "DER-Approved." Although the entire document is reviewed by the FAA, only the technical data (i.e., engineering information) associated with it is approved. In many cases, the technical data is not included in the body of the service document. This is because that document typically contains only the instructions (methods, techniques, and practices) for performing a particular repair or alteration, rather than the engineering information that established compliance with the applicable airworthiness standards. Refer to AC 20-114, Manufacturers' Service Documents, for methods a manufacturer may use to indicate that the FAA has approved service information.
The terms "methods, techniques, and practices" and "technical data" have often been confused. While the concepts are related, each has a distinct meaning in 14 CFR.
1. The methods, techniques, and practices referenced in section 43.13(a) are the step-by-step instructions for performing maintenance (including inspections), preventive maintenance, and alterations. These "how-to" instructions are normally contained in manufacturers' maintenance manuals and other service documents, and are usually based on approved technical data developed by the approval holder.
2. Technical data consists primarily of engineering information. It includes drawings and specifications that define the configuration and design characteristics of an article, and information on materials, dimensions, and processes necessary to define structural strength. Substantiating data is technical data used to establish that the aircraft or other article, if repaired or altered using the instructions that the substantiating data supports, would be returned to its original or properly altered condition in accordance with section 43.13(b). The operator is responsible for showing that any substantiating data is directly related to the change that is being evaluated. This is especially important when it is necessary to substantiate a change using service experience, maintenance and alteration experience, and reliability data. Accordingly, the technical data, when substantiated, is considered acceptable to the Administrator even in cases when it does not require the FAA's explicit approval.
Maintenance manuals and/or restoration/overhaul manuals may contain technical data. For example, if the manual specifies the required materials, dimensions, or other design information, this represents technical data.
An allowable damage limit in an SRM represents an acceptable method for accomplishing a repair or authorizing a continue-in-service condition. The TC holder's damage "limit" is based on approved substantiating data-i.e. an engineering analysis showing that even with such damage, the airplane would then still meet the appropriate airworthiness standards. In many cases a higher limit can also be shown to comply with those standards.
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