A light bulb comes on and you have an idea for how to build a better mousetrap or, in this case, an aircraft replacement part. You fabricate the part and do some initial testing. The results of that testing buoy you on to thinking this could be something great for the industry and hence your business. Now what? How do you get that part approved for sale? Here is a quick look at how the PMA approval process works.

The FAA gives guidance on the approval of parts under order 8110.42B, Parts Manufacturer Approval Procedures. This document, available on the FAA Web site, prescribes the responsibilities and procedures for approving PMA parts, also known as replacement and modification parts.

To start, the part manufacturer needs to apply with the FAA to receive approval. "The main thing is that the part is developed as a replacement part on their own," said Wayne Shade, president/FAA DER, Innovative Consulting Solutions, Inc. "There are a number of ways to make a part," Shade said. "Two of the most common are identicality, and test and computation, which is also referred to as reverse engineering."

Identicality

The process of making a part through identicality is fairly straightforward. OEM data is used. This data can be obtained in a number of legitimate ways, through the public domain. "The easiest way is through the OEM," said Shade. Many OEMs have agreements with parts manufacturers to produce replacement parts for their aircraft, especially older, out of production models. These licensing agreements allow the part to be reproduced using the OEMs original data and drawings.

The data can also be obtained through the Freedom of Information Act (FOIA). For example, if you have a military part number, the FOIA allows for the information to be disseminated to the public. To learn more about how to make a request under the FOIA, go to www.usdoj.gov and look for the DOJ FOIA Reference Guide.

Often, if the manufacturer is working with the OEM under a licensing agreement, then the agreement may stipulate that the part can only be sold through the OEM. If that is the agreement, then the part can be made using a supplemental type certificate (STC). "Typically in a case like that, a royalty fee is involved," said Shade. Sometimes, however, the OEM will give the authority to make a part without a royalty agreement.

If there is no agreement with the OEM, care must be taken in obtaining the data with which the part is made. A legal opinion may be advisable before beginning to ascertain the ramifications of using specific sources. "It’s very difficult now [to get OEM data]," said Shade. "In the early days, there was more of a relationship between the OEM and the parts manufacturer and outsourcing was based on that relationship."

With identicality, the applicant sends the appropriate Manufacturing Inspection District Office (MIDO) a document from the type certificate (TC), supplemental type certificate (STC), or technical service order (TSO) authorization holder authorizing use of their data package. The applicant uses this evidence to show that the data submitted are FAA-approved and identical to the original part.

Test and Computation

The test and computation method involves developing the product without the benefit of OEM data. This method can be preferable according to John Wicht, FAA coordinator at Rapco. "[Identicality] doesn’t give you a lot of options," he said. "We’ve always chosen testing and computation primarily because it allows us to incorporate the design modifications that are available to us."

Since many general aviation aircraft were certified in the 1950s and 1960s, the technology of their parts is of that era as well. "The advantage with testing and computation is that we can take some of the modern engineering and manufacturing techniques and incorporate them to achieve equal or better results of the actual part," Wicht said.

With this method, the applicant sends the Aircraft Certification Office (ACO) a data package for review and approval. This data package describes the part design, which includes materials, processes, test specifications, system compatibility, maintenance instructions, and part interchangeability.

The package also includes a test and substantiation plan to show compliance with applicable airworthiness standards. The FAA cautions that when using reverse engineering the "rigor and scope of the substantiating data should reflect the degree that the design is identical." The more complex the part, the more substantiating information to show equivalency between the parts is needed.

Application Letter

The content of the application letter includes the following:

• Identity of the type-certificated product for installation of the PMA part. Note make, model, series, and serial number of the product as recorded in the upper right-hand corner of the product’s type certification data sheet.

• Identity of the TC holder’s part, including the part’s name and number. Also applicant identifies the drawing and revision level that the PMA part replaces or modifies.

• Optional request for a project specific certification plan (PSCP) if the application is for the design approval of a complex, life-limited, or critical part.

• Statement that certifies the applicant has an established fabrication inspection system (FIS) that meets the requirements of 14 CFR 21.303(h).

• Brief description of the basis for a design approval.

• Draft PMA supplement.

A project specific certification plan (PSCP) is a tool to aid in the design approval process of complex and critical parts. The ACO and applicant can tailor the plan based on the complexity of the part. A template is provided in appendix 3 of 8110.42B.

The MIDO conducts an evaluation of the fabrication system and inspection system that is in place at the manufacturer. "The MIDO will be looking for ways the company is maintaining production quality. They will be inspecting their process controls, manufacturing inspection procedures, etc.," said Shade. "If the company is making a new, but similar part, it is a little more straightforward, once the inspector is assured of the fabrication inspection system."

The MIDO’s workload varies and the speed of the inspection and evaluation process is dependent on that. "The MIDO has streamlined the process," Shade added. "Where I find a slowdown is at the ACO level," said Shade. "Especially if it’s a totally new inspector, it may take a little more time." There are about 27 MIDO offices in the country and 13 ACO offices.

If a parts manufacturer has already been through and received ISO 9001 certification Shade said this can help in the inspection process because the company already meets the majority of the requirements that the FAA will require via their ISO certification.

For more information on the PMA parts approval process go to www.airweb.faa.gov.