Commercial Parts – What Are They?

Lately we’ve had a number of questions about commercial parts.  Industry members want to know what are they, and how do the new commercial parts rules affect the marketplace?

The definition of commercial parts can be found at 14 C.F.R. 21.1(b)(3).  They are defined as anypart that is identified as a commercial part by a design approval holder.  To understand how to define such parts, though, a design approval holder must go to the defining criteria found in section 21.50(c) (discussed below).

The 2009 change (which become fully effective in April 2011) to the regulations modifieded the FAA’s standard for when a person needs to get a PMA or other production approval for the fabrication of a part.

Previously, the test was whether the manufacturer knew at the time of production that the part was going to end up on a type certificated aircraft. This standard was tested and established in the Pacific Sky case in 1993:

“The most reasonable interpretation of the regulation is that Complainant must show that Respondent knew or should have known that it was substantially certain that the parts produced by Respondent without a Parts Manufacturer
Approval would be installed on type-certificated products.”  In the Matter of Pacific Sky Supply, FAA Order No. 93-19; Docket No. CP91NM0319 (June 10, 1993).

That case goes on to explain that:

This is a somewhat more difficult burden to meet than Complainant’s reasonably likely standard. It more appropriately balances the equities involved — the FAA’s duty to promote aviation safety n8 by controlling the spread of unapproved parts, and the producer’s right to produce parts without FAA approval when it is insufficiently probable that the parts will find their way into type-certificated aircraft.  In the Matter of Pacific Sky Supply, FAA Order No. 93-19; Docket No. CP91NM0319 (June 10, 1993).

The 2009 change alters the language to reflect the proposal that the FAA Administrator rejected in 1993.  The new language of 14 C.F.R. 21.9 states that:

If a person knows, or should know, that a replacement or modification article is reasonably likely to be installed on a type-certificated product, the person may not produce that article unless it is ….

This section then goes on to list certain categories of parts that are considered acceptable under this provision.  Commercial parts are listed as one of the categories of acceptable parts – they reflect an exclusion from the general requirement to obtain production approval.  See 14 C.F.R. 21.9(a)(4).

An important element of this new rule is that the prior industry understanding of the term “commercial parts” – meaning parts that are not designed for use in aviation but that are chosen by the installer for installation, is no longer the definition used by the FAA.  Under the old standard, the installer was responsible for assuring airworthiness at the time of installation.  While the installer still bears this regulatory obligation (to assure airworthiness at the time of installation), commercial parts will be parts that have been previously subjected to engineering analysis by a FAA design approval holder, so the burden on the installer to confirm airworthiness would be theoretically decreased.

We say “theoretically decreased” because as of this time, we are not aware of any design approval holder that is designating commercial parts. We have been informally surveying design approval holders for over two years and the results have remained the same – none of the design approval holders intend to designate commercial parts.

The commercial parts category was conceived as a “safety valve” to permit the FAA to work with design approval holders in order to continue to have a category of parts that are used in aviation but that are not subject to direct FAA production approval.  Instead of that category being defined by the producer’s intent, it would be explicitly defined by an application made by a design approval holder and approved by the FAA.  However, the utility of that category is obviously undermined if it is not used, and the change in the regulatory standards identifying which parts need to be approved by the FAA becomes more pronounced – and has a more noticeable affect on the industry – when the regulatory change is not buffered by a use of the “commercial parts” designation.

A discussion of the protocol for identifying commercial parts can be found at 14 C.F.R. 21.50(c).  Essesntially, a design approval holder may submit a request to the FAA seeking FAA approval of a commercial parts list.  The request must be substantiated with engineering data to show that:

  1. “The failure of the commercial part, as installed in the product, would not degrade the level of safety of the product;”
  2. “The part is produced only under the commercial part manufacturer’s specification and marked only with the commercial part manufacturer’s markings;” and
  3. “Any other data necessary for the FAA to approve the List.” – under this provision the FAA may attempt to impose any other requirement at will.

The FAA has also published an advisory circular about commercial parts that provides additional guidance.


About Jason Dickstein
Mr. Dickstein is the President of the Washington Aviation Group, a Washington, DC-based aviation law firm. He represents several aviation trade associations, including the Aviation Suppliers Association, the Aircraft Electronics Association, the Air Carrier Purchasing Conference, and the Modification and Replacement Parts Association. He also represents private clients drawn from the spectrum of the aviation industry.

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