CHAPTER 4. USE OF DESIGNEES
4-1. General. This chapter covers using FAA designees in the STC process. You may propose to use an FAA designee to perform a task that an FAA employee would normally perform.
a. The designee system helps us by designating private persons to act as representatives of the Administrator. Regulatory information describing the designee system is found in 14 CFR part 183, Representatives of the Administrator. Help may include examining, inspecting, and testing of persons, aircraft, engines, or propellers, and approving or recommending approval of certain types of data for compliance with 14 CFR or CARs.
b. The types of designees applicants most often use in the STC application process are designated engineering representatives (DERs), designated manufacturing inspection representatives (DMIRs), and designated airworthiness representatives (DARs).
(1) We encourage applicants to use the internet to search for consultant DERs and DARs.
The listings are available for downloading at http://www.faa.gov/other_visit/aviation_industry/designees_delegations/find_designees/.
(2) Designees are not FAA employees. Consultant designees (consultant DERs and DARs) are private individuals who represent the Administrator, and are allowed to charge for their services. They set their own rates and run their own businesses. Company DERs and DMIRs represent the Administrator, but are employees of the organization making the STC application.
4-2. Designated Engineering Representatives (DERS).
a. DERs may only approve or recommend approval of data, as complying with the requirements of FAA airworthiness standards. We may authorize DERs to witness tests on our behalf, in accordance with approved test plans. We may also authorize DERs to approve test plans. A DER’s authority is limited to specific functions within one or more of the following categories:
(1) Structural.
(2) Powerplant (installation, engine or propeller).
(3) Systems and equipment (mechanical or electrical).
(4) Radio.
(5) Engines.
(6) Propellers.
(7) Flight analyst.
(8) Flight test pilot.
(9) Acoustical.
(10) Administrative or management.
b. An administrative DER acts as a focal point for FAA coordination activity.
c. An applicant’s management DER performs certification management duties for us similar to that of the FAA project engineer. This includes organizing the certification program and directing, overseeing, and managing technical assessments and findings of compliance. The management DER ensures all technical data required to show compliance (except in those areas we reserved) is reviewed and approved. The management DER is usually a consultant DER whereas an administrative DER is usually a company DER.
d. Company DERs may only perform delegated functions for the organization employing them.
4-3. Designated Manufacturing Inspection Representatives (DMIRS).
a. A DMIR, within limits prescribed by 14 CFR § 183.31, and under general FAA supervision, may:
(1) Issue an original standard or special airworthiness certificate when they determine that the product(s) conforms to the approved design requirements and are in a condition for safe operation.
(2) Issue an experimental certificate to show compliance with 14 CFR chapters I and III for aircraft which the production approval holder (PAH) holds the TC and has undergone changes to the type design that require an FAA official flight test.
(3) Conduct conformity inspections to determine if:
(a) Prototype products and related parts conform to design specifications.
(b) Production products and related parts conform to the approved type design and are in a condition for safe operation.
b. DMIRs may only perform delegated functions for the organization that employs them.
4-4. Designated Airworthiness Representatives (DARS) and Organizational Designated Airworthiness Representatives (ODARS).
a. We delegate a DAR/ODAR to perform examinations, inspections, and testing services necessary to issue certificates.
b. We may use a manufacturing DAR/ODAR for conformity inspections and issuing the experimental and standard airworthiness certificates. However, the appropriate MIDO and FSDO delegate these functions to the DAR/ODAR before the DAR/ODAR executes the authorized functions. The DAR is not limited to work for only one entity, but is restricted by geographical limits unless granted permission to expand to other geographical areas by the cognizant MIDO.
4-5. Responsibilities of the Applicant. You are responsible for ensuring that each designee has the appropriate FAA authorization to approve data, perform inspections, and witness tests, and other particular functions, for the modification. You are also responsible to coordinate with us to ensure that the designee is authorized and delegated to perform each test and inspection. You should also coordinate the certification plan with the DERs before submitting it to the ACO since the DERs must understand the modification and comment on the proposed method of compliance.
CHAPTER 5. DATA
5-1. Required Data.
a. Data submitted to us should demonstrate that your modification, when installed on a type-certificated product, complies with the applicable regulations. You or your representative should obtain, organize, and submit this data to us for review and approval.
b. You can divide design data into two major categories: descriptive, and compliance or substantiation data. Descriptive data defines the design of the modification, while compliance data substantiates that the design meets the applicable regulations.
c. A copy of all data will remain on file with the FAA. However, we treat this data as your property and will not release it outside the agency without your consent.
d. Identify all data submitted. This includes title, drawing or report number, revision level, date, and your name. Each page of a report should contain enough information for complete identification. Identify the FAA project number.
e. Descriptive data requirements for a “one-only” STC are different than the requirements for a “multiple” STC. However, the same level of safety is required for either type of STC.
f. Accomplish the following tasks according to 14 CFR §§ 21.21 and 21.33(b) before submittal:
(1) Check all descriptive and substantiation data for completeness and correctness.
(2) The descriptive data conforms with the actual configuration of the modification.
Base all stress analyses, test plans, and test results on the descriptive data.
(3) Identify the data describing and substantiating the modification. Present it orderly and clearly, stating how it contributes to the findings of compliance.
5-2. Descriptive Data.
a. In general, descriptive data should completely define, or describe, a given design. It may include drawings, sketches, marked photographs, process specifications, and so forth. We will verify the data for compliance with the applicable airworthiness regulations.
b. A “one-only” STC descriptive data package applies to only one installation/modification. The package may consist of marked-up photographs, sketches, written descriptions, marked-up excerpts from manufacturers’ parts catalogs and maintenance manuals, and similar document excerpts. If you submit descriptive data other than drawings, the data must be of sufficient quantity and quality to properly ascertain the nature of the modification. This 47
includes your defining all critical equipment, parts, and attachments, and identifying any components of the original product that were removed.
Note: Since parts catalogs are not FAA-approved documents, excerpts from parts catalogs alone are not sufficient.
c. A “multiple” STC descriptive data package should completely and accurately describe the fabrication, assembly, and installation of all portions of the modification. The descriptive data must be adequate for reproduction of parts and/or installation of subsequent modifications on other serial numbers of the same model type-certificated product. An acceptable package includes, but is not limited to:
(1) Engineering drawings,
(2) Material and manufacturing processes,
(3) Specifications and tolerances,
(4) Data necessary for fabrication of all parts and assemblies, and
(5) Installation drawings and/or instructions. See appendix 2.
d. Technical information should include the following, when applicable:
(1) Identification (title, drawing or report number, product applicability, revision level, date, and applicant’s name).
Note: When original equipment manufacturer or supplier parts, accessories or equipment are involved, whether new or used, provide purchase orders or other acceptable traceable documentation, including name plate identification, part number, revision letter, and serial number.
(2) Materials used, identified by material specification.
(3) Material test criteria and procedures.
(4) Fasteners used and locations. Identify each rivet, bolt, nut, screw, or other fasteners by specification or standard part numbers, such as Air Force-Navy Aeronautical Standard (AN), National Aerospace Standard (NAS), or Military Standard (MS).
(5) Dimensions, with tolerances included.
(6) Vendor data (manufacturer and part number of purchased parts).
(7) Process specifications.
(8) Ratings and power requirements of electrical equipment.
(9) Weight and balance data of assemblies and equipment items to be installed, and/or the complete modification, including:
• A complete list of parts added and/or removed.
• Updated aircraft equipment list.
(10) Installed placards.
(11) Instrument markings.
(12) Qualification test procedures.
e. Define the design of equipment or components to be installed, purchased and/or furnished. If the item is TSO approved, the nameplate data may be adequate. Other equipment may require a source-control drawing identifying the equipment by manufacturer, part number, drawing number, revision level, or any other necessary data. Installation instructions for the modification should include all applicable information provided by the equipment’s manufacturer.
Note: When a “multiple” STC kit is produced, it should contain an inventory of ALL parts and installation instructions. Details of the parts manufacturing data that is proprietary need not be included in the kit.
f. Include process specifications necessary for production of parts in the descriptive data package. Include all materials, fabrication, and assembly procedures.
(1) Industry standards and specifications include various SAE International Aerospace Standards, AN, MS, and NAS specifications, and various military handbooks. Supply a copy of each standard and specification as part of the descriptive data package. You may use certain other industry standard specifications or develop non-standard specifications.
(2) Non-standard specifications should include a complete and unambiguous definition of the materials to be used, detailed procedures, critical processes, temperatures, times, inspection criteria, rework limits, and so forth. We will review any nonstandard specification.
g. Identify installation instructions with a document number and an original issue date or revision level and date. They should be complete enough to allow the installer to duplicate the 49
installation.
h. Provide an aircraft flight manual supplement to the pilot if required by the modification (see 14 CFR § 21.5), regardless of the method used to provide operating instructions on the original aircraft.
5-3. Substantiating/Compliance Data.
a. In general, substantiating/compliance data is intended to show compliance with the applicable regulations. This data may include analyses, test plans and reports, and instructions for continued airworthiness and operations. You may use previously FAA approved data appropriate for the installation. Submit a copy of this data and authorization letter to us.
Note: If the ACO engineer has relevant tests or other engineering data available from previous approvals, they may waive your requirement to conduct such tests or submit duplicate data for a current STC application. In this case, we will provide a brief rationale explaining these findings and include it in the project file.
The ACO engineer may use the relevant data for comparison purposes, but won’t disclose the data or its source to the current applicant. We will not copy substantiating data from a previous project file and put in the subsequent project file.
b. The compliance checklist specifies each applicable certification rule and the method by which compliance will be shown (analysis, structural test, ground test, flight test, and so forth).
A checklist is a concise, easily reviewed program outline that ensures all parties addressed the applicable certification rules and their means of compliance. Prepare the compliance checklist and submit to us after the certification basis is identified (see chapter 3). Examine and identify each rule for applicability to the proposed modification, along with a method of showing compliance. You can update the checklist later to identify the report, letter, or test, used to show compliance. For a sample format, see figure 2-5. To identify the appropriate certification rules, you may need help from the FAA project team.
c. A basic load analysis is necessary when the structure is modified or structural loads are changed. The analysis establishes the flight, ground, landing and other applied loads determined from weight, center of gravity, power, and aircraft aerodynamic characteristics using design speeds, and load and safety factors specified in the certification basis. These loads, with the structural analysis and/or tests, form the foundation used to provide the required structural substantiation only if experience has shown this method to be reliable. Ultimate load testing may be required when limit load tests may be inadequate.
Note: Have all structural loads approved by the ACO before you perform a stress analysis or test. The ACO may have a DER recommend approval.
d. Structural analyses establish mathematically that the appropriate structural strength requirements were met. These analyses build on the basic loads and material allowable data and may include static stress, fatigue, fail-safe, and damage tolerance. You should ensure that the analytical methods and assumptions you used apply, that you addressed all applicable loading conditions, and that you showed positive margins of safety for all structural elements.
e. Allowable material strength properties are established for the materials used in substantiating primary aircraft structure. The properties must be FAA-approved.
For metallic materials, we recommend using, Metallic Materials Properties Development and Standardization Handbook (MMPDS), but may accept other data. Nonmetallic materials may require developing allowable data.
f. If you anticipate using computer models for substantiation, discuss the validation of those models in the certification plan.
g. Safety assessments evaluate the effects of foreseeable failures of the aircraft structure and/or systems. The depth and level of the detail depends on the severity of the failure conditions, functions performed, and the complexity and novelty of the aircraft or modification.
Faults that are undetectable are presumed to exist at the same time as each other single fault.
Take any necessary actions (system redesign, aircraft flight manual procedure changes, and so forth) to correct unsafe conditions found. We may also require a safety assessment for aircraft systems.
h. Prepare test plans and reports for each required structural, component, software, ground test, and flight test. Test plans should include conformity inspection requirements. Submit them to us for approval before you assemble and test the articles.
i. ICA describes maintenance requirements necessary to maintain product airworthiness.
Provide them in accordance with the applicable regulations, (14 CFR §§ 23.1529, 25.1529,
27.1529, 29.1529, 31.82, 33.4, or 35.4).
Note: For any STC application submitted after January 28, 1981, you must furnish at least one set of the complete ICA to the aircraft owner or operator. See 14 CFR § 21.50.
j. Revise the weight and balance manual and/or aircraft flight manual for the original type design accordingly when modifications change the aircraft weight and balance, the operating limitations, procedures, performance, or the loading instructions for the modified aircraft. The applicable weight and balance data should be FAA-approved and documented in a supplement to the original weight and balance report. Update the aircraft equipment list.
k. Structural life limits are established based on fatigue test data with adequate factors of safety applied and added to the airworthiness limitations section of the ICA. You may have to produce new structural life limits when modifications change an aircraft designed with safe-life structures. (These are structures that don’t fail when subject to the cyclic and sustained loads 51
and environments encountered in the service life).
l. Prepare electrical load analysis for the installation and electro-magnetic interference (EMI) reports as appropriate.
5-4. Drawing Package. The drawing package describes the manufacture and installation of all parts necessary for the modification. Identify all part contours, materials, manufacturing operations, dimensions, finish specifications, and other data, either directly on the face of the drawing or by reference to a process specification or other appropriate information. You should assign drawing numbers that follow a logical pattern.
Note: Drawings are a major portion of the descriptive data required for a multiple STC. All drawings should be DER or FAA approved before our acceptance and conformity inspection. See 14 CFR § 21.33.
5-5. Drawing Revision Levels.
a. Each revision level should identify the changes and approval dates on the drawing.
These items should be reflected in the drawing list submitted with the drawing package for FAA approval.
5-6. Good Drawing Practices. Thoroughly check drawings for accuracy and completeness before submitting them to us. This will reduce the likelihood that we will return drawings with unacceptable errors to you for resubmission. See section 5-10.
5-7. Tolerances.
a. Note the standard manufacturing tolerances on the drawing. You may refer to American National Standards Institute (ANSI) Specification Y14.5, Dimensions and Tolerancing, 1994, for guidance.
5-8. Drawing List. Prepare and submit a drawing list, or master drawing list (MDL), with the drawings. Include installation instructions, any process specifications, drawing or document number, revision level, any engineering change orders in effect, the date prepared, and the approval dates of all material. See appendix 2.
5-9. Examples.
a. See appendix 2 for a drawing list and several sample drawings. This is one way of meeting drawing package requirements. Process specifications for plating and inspection, as well as the installation instructions, are included in the drawing list, and they are divided into installation and manufacturing data. A revision control page is shown, but may not be needed on a very short drawing list.
b. We also included drawing examples showing a detail part, a subassembly, and an 52
installation in appendix 2. These illustrate the type of information required on drawings of various types and an acceptable way of organizing a drawing system.
5-10. Guidelines for Checking Drawings. Before you submit drawings to us, have them reviewed using a guide or other system, by someone other than the person responsible for drafting them. For descriptive data, the first such check may be performed by the engineer. The following is an example of a drawing checklist:
Note: Company standards are allowed as long as they meet the intent of this guidance material.
a. Make sure the design is both accurately and completely portrayed. Then, review the contents of the drawing.
b. Each part should be correctly drawn and illustrated, with all necessary views of the part shown on the drawing.
c. Dimensions:
(1) Check the accuracy of all dimensions by scaling and, where advisable, also by calculation.
Note: Preserve all calculations.
(2) Check the completeness of the dimensions to verify that no adding or subtracting is required for a needed dimension.
d. Tolerances should not be too “fine” or too “coarse,” which might impact the duplication accuracy or operation.
Note: Each production part should be within established tolerances.
e. Check finishes for proper specification on each part and assembly drawing.
f. Check material specifications to verify that every specification is correct and that all necessary information is given.
g. Part compatibility:
(1) Check for interference, or compatibility of each adjacent part, in the final assembly to ensure proper clearances. Use “worst case” tolerance limits.
(2) Lay out the mechanical movement clearances to scale and check them for interference (considering tolerances) in all positions at the extreme limits of travel.
h. Check detail parts to verify that all screws, bolts, pins, rivets, and so forth are standard product quality parts and that, where applicable, you have used stock sizes.
i. Present the following information in the Title block:
(1) Drawing number to identify the print for filing purposes and to prevent confusion with other prints.
(2) Name of the part or assembly.
(3) Scale to which it is drawn.
(4) Date.
(5) Name and address of the applicant and firm.
(6) Name of the draftsman, checker, and the person who approved the drawing.
(7) Product model, detail or assembly it is to be used on.
(8) Drawing number of the next higher assembly.
j. In the Bill of Material block, present:
(1) Number of the part or assembly.
(2) Name of the part or assembly.
(3) Material from which the part is to be constructed.
(4) Quantity required.
(5) Source of the part or material.
k. In the Revision block, list:
(1) Identification symbol.
(2) Numbered or lettered changes (A through Z is followed by AA through ZZ. Do not use I, O, Q, and X.
(3) Date.
(4) Nature of the revision.
(5) Authority for the change.
(6) Name of the draftsman who made the change.
Note: To distinguish the corrected drawing from its previous version, the title block may have a space for entering the symbol designating that the drawing was changed or revised.
l. Review other details:
(1) The border around the drawing defining the work area should be 7/8 inch to 1/2 inch from the edge.
(2) Dimensions and views should be sufficient to describe the part or assembly, and include a full sectional view of assembled parts. We prefer decimal dimensions. Avoid views with hidden lines when possible. Do not include dimensions to hidden lines.
(3) Note the tolerances on the drawing when they are different from those called out in the Title block.
(4) Indicate parts by a name, followed by a description of what they do, and where they are located on the product.
(5) Indicate the finish operation/process such as cadmium plate, zinc chromate coat, anodize, shot peen, tumble, sand blast, vinyl wash, epoxy, and so forth.
Note: Zinc chromate and vinyl wash denote primers. Specify final finishes as well--enamel, epoxy, lacquer, and dope. A complete designation of a finish process/operation should include a reference to a specification.
(6) Indicate the standard tolerances specified by the applicant/designer.
(7) Do not reference general notes from the field of the drawing. They apply “Unless Otherwise Noted.”
(8) Specific notes (also listed under the general notes column) apply to particular parts, areas or operations and are usually referenced from the field of the drawing by the note number enclosed in a triangle.
m. Review the drawing in its entirety. Add explanatory notes as needed to increase its usefulness.
n. For further advice see 55