The following information is based on an article printed in the November
2004 issue of “AOPA Pilot” magazine and deals with FAR21.303 rules
governing replacement parts on certified aircraft. Basically, we are required to
use parts made by the certificated airframe and engine manufacturer. Or, in some
cases, a company will obtain FAA approval (PMA) to produce a part that can be
used in place of the part made by the certificated manufacturer. Another case
where different parts can be used is “standard parts” such as hardware built
to certain standards (NAS, AN, MS and SAE). In other words, parts as good or
better than the identical part used by the manufacturer. This now includes such
items as resistors, diodes, transistors, and other electrical items. The next
application is similar to the PMA parts and that is parts built to a technical
standard order or TSO. This covers common production parts such as tires, seat
belts, instruments, and avionics.
Now comes the part of great interest to our VG-21 owners that covers “owner
produced parts”. In a nutshell, you, the owner, can have a part made as long
as you (A) provide the design or performance data, (B) provide the materials,
(C) provide fabrication process, and (E)) provide quality control or supervise
the part manufacturing. It also states that the owner can hire someone to make
the part as long as the owner fulfills the conditions for parts manufactured and
does not make the part for the purpose of selling. The part must be used on the
Recently, I received a request for help locating landing gear torque links. None
were found. So we used the above procedure for parts manufacture. Fortunately,
we have a modem aviation-related machine shop on our airfield and armed with
manufacturing drawing and the required materials, the request for new links has
been fulfilled. The good news is the machine shop equipment is computer operated
so additional links can be easily made. At first I thought the price for the six
links we had manufactured was high until I saw the purchase order for a Cessna
310 nose gear lower link - $1,800. Based on what the aluminum bar stock cost
plus the cost of bushings and grease fittings, and the anodizing process, the
cost per link is less than $200 per link. Two links are required per gear leg.
So if you need torque links, contact us as we can as your mechanic agent.
I’m asking for feedback from you members. This past year one of our
member’s Varga was disassembled to a great degree for repairs at our airfield.
I paid an active part in these repairs. It was my observation that this aircraft
had not received a decent annual inspection in years. I made the suggestion that
the next annual be done at a maintenance facility on our field and the owner
agreed. I then produced a customized job card for this task and I am proud to
report it worked out well. What I’m asking is should I make this document the
maintenance item in the next Newsletter?