William P Rourke

1200 Hwy 74. So., Suite 6‐211

Peachtree City, Ga 30269

Ms. Brenda Courtney

Manager, Aircraft and Airport Rules Division

US Department of Transportation

Federal Aviation Administration

800 Independence Avenue, SW

Washington, DC 20591

April 5, 2010

RE: Petition for Rulemaking (No. FAA‐2008‐0855)

Dear Ms. Courtney,

Thank you for your response to my Petition for rulemaking regarding the installation of non‐TSO’d

equipment in aircraft certificated in the primary airworthiness category.  The specific change to Title 14

CFR I am proposing is to FAR 21.17(F). Specifically, I am proposing an additional subparagraph, titled

21.17(f)(3),  following 21.17(F)(2) stating:  

“(3)  Primary Aircraft must meet the equipment requirements of part 91.205 however, may use flight

instruments and equipment approved for use in other special classes of aircraft, including equipment

designed exclusive of the requirements of part 23.”

In your response to my petition you state “the type of project you are proposing is not a project that will

likely be selected for rulemaking because it does not pose an immediate safety concern.”  I take

exception to this statement as the safety benefits, in addition to the affordability of this equipment, are

precisely why I am proposing this change.  

The current general aviation fleet consists of tens of thousands of aging single engine, personal use,

aircraft which meet the requirements for conversion to the Primary Category under the provisions of

FAR 21.184(c).  Most of these aircraft are equipped with antiquated instruments, which in some cases

are not even allowed to be used in Part 25 or 121 aircraft due their disastrous operational history.  An

example of this is the turn coordinator.  Many pilots, and their passengers, have perished when their

primary attitude display failed, either as a result of a system failure or failure of the instrument itself,

leaving only an antiquated turn coordinator to maintain wings level in IMC.  While the turn coordinator,

which was designed prior to WWII, was all that was available when many of these aircraft were built,

technology has since rapidly improved. Unfortunately, due to the expensive part 23 certification
process, and resulting equipment costs, many current “certified” airplane owners are unable to afford

this modern equipment.

While the need for a higher level of Safety in the design and certification of commercial use aircraft is

certainly appropriate, the equipment required was so cost prohibitive replacements were not mandated

in the general aviation fleet.  Even today’s “lower cost” certified equipment, intended for newer Part 23

aircraft, often far exceeds the value of their older general aviation aircraft counterparts.  Examples

include the Garmin G‐1000 EFIS display costing approximately $20,000 dollars or the Aspen EFIS which,

for a VFR only installation, can exceed $10,000. By comparison, a standard Cessna 150 can be bought for

less than the cost of installing either of these displays in that same airplane.  As a result, the additional

cost of this “TSO’d” equipment has proven to be prohibitive to the majority of “private use” GA aircraft

owners.  This is in stark contrast to the thousands of LSA and experimental aircraft, certificated in special

airworthiness categories, currently using electronic flight displays, and other noncertified equipment in

our National Air Space System.  This equipment was developed, and subsequently installed exclusive of

the requirements of FAR par 23. These LSA and experimental aircraft are also required to meet the

requirements of 91.205, per their operating limitations, and the equipment installed has been found by

the administrator to meet these requirements.  One benefit of this “off the shelf” non‐TSO’d equipment

is shown in a cost comparison relative to their “certified” cousins.  For example, a basic EFIS display

made by Dynon Avionics, which is widely in use in the LSA and experimental communities costs

approximately $1800 with its larger Skymap display, which offers a similar product to the G‐1000 can be

purchased for $4000 dollars. Both have been found by the administrator to meet the requirements of

91.205 in non‐part 23 aircraft.

Ms Courtney, the arguments I am making for the allowance of this change are both safety related and

are of a benefit to the public.  The safety case is based on replacing older antiquated equipment, with

affordable, aircraft specific, equipment widely in use in other special airworthiness certificated aircraft.  

The example of replacing the Turn Coordinator with an affordable, and fully functional, EFIS display;

having all the functions of the Primary flight instruments, and using the original primary mechanical

instruments as a backup is one example. The accident statistics prove my case as is evident in the FAA’s

actions in changing part 25 and 121 aircraft standards. Most, if not all, of the economic arguments I have

made are identical to those made by the FAA in the original NPRM establishing the Primary Category.  

Further, the establishment of the Primary Category itself was entirely for the economic reasons,

benefitting the public, rather than Safety related.  Is the Government the only entity allowed to propose

a rule which is not Safety related?

Please advise me if this letter does not provide all the necessary information need to complete my

petition for rulemaking.

Sincerely,

William P. Rourke

(678) 525‐3927