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General Question: FAA guidlines for "Qualification"

General Question: FAA guidlines for "Qualification"

General Question: FAA guidlines for "Qualification"

When certifing a new installation on an aircraft (Part 25 for example) we always "qualify" the components by doing environmental/vibration/fungus/EMI/RFI/famon/feast/fire/brimstone testing.

What drives this practice, I assume 25.1301 and 1309 are the drivers.  Is there any guidance on this practice of qualification?  I've looked over AC25.22 and a few others with little information on a big task we all perform.

Basically I'm looking for some written rules/guidance/orders or even an explaination as to why the industry has gotton so involved with component qualification.  I'm told in the "olden" days catalog data would suffice...

Thanks for any information in advance!


RE: General Question: FAA guidlines for "Qualification"

A resource that might help you a bit more (rather than 25.1301 and 25.1309) in your specific question concerning environmental qualification testing would be Advisory Circular 21-16D, which directly addresses the use of RTCA DO-160D testing.  DO-160D testing is one source of the type of environmental qualification testing you describe, and it may be used to qualify a piece of equipment for a Technical Standard Order (TSO) authorization.

The DO-160D testing may also be used by a Type Certificate (TC) or Supplemental Type Certificate (STC) applicant to qualify portions of the aircraft installation with respect to environmental conditions.

In summary a TSO assures a standard level of testing is accomplished on an individual piece of equipment that is intended for use on an aircraft.  The environmental qualification testing you cited can be used to support the application for a TSO.

A TC or an STC approves an aircraft installation.  The environmental qualification testing you cited can be used to support the application for a TC or an STC.

RE: General Question: FAA guidlines for "Qualification"

I'll check out AC21-16D, thanks.

I understand that components are qualified as part of obtaining TC/STC, and that the TSO process involves qualification testing.  A TSO'd product can be used in a TC/STC installation without the need for qualification (if it's being used for the purpose intended).

The big question:  What requirements drive this testing, is the requirement- "enough testing so a DER has a warm fuzzy that the component will live happily where it is installed"?

That seems to be a large area of interpretation if thats the case.

Thanks Again,


RE: General Question: FAA guidlines for "Qualification"

Actually, although your language is not FAA "legalese", you have stated the case in practical terms.  DERs need warm fuzzies too, I guess.  While I am not aware of any specific FAR that calls out the type of testing you described, in Advisory Circular 21-40 (The STC Process), Qualification Testing is mentioned as one of the "Methods of Showing Compliance" on page 15.

I suspect that the industry has gravitated towards the position that since RTCA DO-160D testing is considered by the FAA to be a good standard for testing the boxes (i.e., TSO'd individual pieces of equipment), and because AC21-16D says it can also be used to qualify installations as well, then RTCA DO-160D has probably become a "de facto" standard to give the DER warm fuzzies.  I am not a DER (although I have worked around and for them for 15 years, designing aircraft electrical installations), so I can't say with authority what drives a DER to expect the testing you describe.  Perhaps someone who IS a DER can chime in with their specific guidance that tells them when to expect environmental qualification testing of the intensity you describe.

RE: General Question: FAA guidlines for "Qualification"

Look at it from another point of view: if an airline is equipping an aircraft with a particular type of black box, and they have to choose between one that's been tested IAW DO-160, and another that isn't, which one would you buy?
A DER would have to investigate the alternative method of testing applied to the black box that wasn't given the DO-160 treatment, and determine that it satisfies the reg's.  Even if the airline saves money on black box "B", they spend their savings on the consultant's fee.

Steven Fahey, CET
"Simplicate, and add more lightness" - Bill Stout

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