What makes a part airworthy?

Parts is Parts What makes an aircraft part airworthy? Joe Hertzler All new parts installed during the maintenance function have to be manufactured to one of the quality standards of 14 CFR Part 21.303. The purchase, installation, and...


Parts is Parts

What makes an aircraft part airworthy?

Joe Hertzler

The purchase, installation, and approval for return to service of installed aircraft parts, combined with inspection of those parts as a whole, makes up the aircraft maintenance function. The regulations that govern the approval of new replacement parts can be found in CFR Part 21. Part 21 establishes the quality standard for the manufacturing of new replacement parts. (Used parts will be addressed separately later in this issue.)

Approval of new parts
An approved part is one that has been manufactured as part of an FAA-approved quality assurance process (quality standard) and successfully passed the inspection criteria.

As a maintenance organization, certificated repair station, or otherwise, you are responsible for ensuring that all new parts installed during the maintenance function have been manufactured to one of the quality standards of 14 CFR Part 21.303. Following are the five possible quality standards for new parts.

PMA - (Parts Manufacturing Approval) Applies only to specific part numbers and is usually associated with STC or a direct replacement (non-OEM) part.
PAH - Parts produced under a type or production certificate.
TSO - (Technical Standard Order) Applies to a specific FAA-approved design. The organization manufacturing the TSO parts must hold TSO authorization from the FAA.
Standard parts - Parts that are manufactured in accordance with an industry recognized standard such as AN, NAS, MS hardware and certain non-programmable electronic devices.
Owner-produced parts - Parts produced by the aircraft owner (or the agent) for a specific purpose and for the repair of his or her aircraft.

Note: Owner-produced parts are not exempt from FAA approval for complex fabrication.

Approval of used parts
Although 14 CFR Part 21 addresses new replacement parts, a quality standard is required regardless of whether the part is new or used. The quality of a used part is identified by its "approval for return to service" under 14 CFR Part 43, (Reference Part 43.13 and 43.9).

Proper approval for return to service is most commonly in the form of an FAA form 8130-3. The part can be overhauled, repaired, removed-serviceable, etc. Be sure that any used parts are coming from a reliable source along with proper documentation. Keep that data on file as well as provide it to the customer.

Develop an approved vendor list
Develop a simple list of vendors that you have determined will supply approved parts. This will ensure that only approved parts are ordered, thus beginning the quality assurance process before the parts actually get to you.

Additionally, you should provide a procedure that enables the purchasing agents to enlist a new vendor source when they come across one. Develop a checklist of key questions and concerns and provide it to purchasing to help evaluate a new vendor. Then, follow through with detailed quality assurance inspection and verification when the part arrives. Establish a procedure by which vendors are 1) placed on the list, 2) audited regularly, and if necessary, 3) removed from the list. It's also a good idea to make a separate list and audit program for outside service vendors due to the different regulations that organizations are required to follow. An audit of service vendors can be quite different than one for a parts supplier.

Different types of suppliers
Anyone can sell parts. At present, there is no regulation covering the sale of parts. Current rules only regulate parts manufacturing and installation. This is why your company, as the parts installer, holds the responsibility of ensuring that the parts are approved. It is a good practice to require your suppliers to include a statement of conformity with each order. It will help you hold the supplier liable, but will not eliminate your liability.

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