From: "Marvin Kaye" <marv@lancaironline.net>
Subject: Re: [LML] IFR Equipment Requirements
To: lml
Date: Tue, 27 Apr 2004 13:01:41 -0400
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Posted for "Jeffrey W. Skiba" <jskiba@icosa.net>:

I just want to make sure that everybody reads the EAA article on TSO
requirements and IFR Flight
  
a clip is here
What about TSO's?

Another question to be answered is what, if any, of the equipment needs to
be "TSO'ed". In order to address this question, it's helpful to understand
what a "TSO" is. TSO stands for Technical Standard Order, which is defined
in 14 CFR Part 21, section 21.601(b)(1) as "....a minimum performance
standard for specified articles (for the purpose of this subpart, articles
means materials, parts, processes, or appliances) used on civil aircraft."
As you can see from this definition, a TSO is actually a performance
standard to which an article can be manufactured.

When someone says an article is "TSO'ed", what they really mean is that the
unit was manufactured under a TSO authorization. Section 21.601(b)(2) says,
"A TSO authorization is an FAA design and production approval issued to the
manufacturer of an article which has been found to meet a specific TSO".
You'll note that the TSO and TSO authorization deal specifically with design
and manufacture, and have nothing to do with installation or operation.

Now we have an idea what a TSO is, but we still haven't answered the
question of whether or not our instruments and avionics in a homebuilt need
to be "TSO'ed". Our Operating Limitations state that we have to equip the
aircraft in accordance with 91.205, and 91.205 lists the minimum equipment
required, but nowhere is there mention of a requirement for TSO'ed
equipment. Thus, the answer is NO, the instruments and equipment installed
in your homebuilt under the requirements of 91.205 are not required to be
"TSO'ed".

So far, so good, but that's not the whole story. Most builders who plan to
equip their homebuilt for IFR operations don't stop at the minimums, so
let's take a look at some of the other commonly installed equipment and see
what's required.

full article at:

http://members.eaa.org/home/homebuilders/faq/Equipping%20a%20Homebuilt%20for
%20IFR%20operations.html#TopOfPage

  

Jeff.