High Cost of Sportplanes

On Thu, 22 Sep 2005 08:16:50 -0600, bowman wrote:

Ron Wanttaja wrote:

The engines used in production LSAs must meet the consensus standard for
engines, ASTM F 2339-04. It is greatly simplified over 14CFR Part 33, but
there are definite design criteria the engine must meet, documentation
that must be generated, and endurance testing that must be performed.

Is that standard realistic? I don't mean that as the start of another long
war, just as a general question. At one point we subcontracted to produce
airport lighting systems (the rabbit) and that standard encapsulated 1940's
technology. For instance, the wiring harnesses had to be laced since there
was a suspicion of the new fangled nylon ties, and the sequencing was done
with an electro-mechanical stepper relay.

The ASTM engine standard is all of two and a half pages long...about 1/10th the
size of Part 33 (although Part 33 covers stuff like jet engines, too). As far
as I can tell, it does not require specific implementations, such as the lacing
you mention).

Here's an example, from Paragraph 5.6, "Electronic Engine Controllers (EEC)":

"...for protection against radiated EMI/HIRF, the harnesses or cables should be
shielded from each sensor to each end point and electrically bonded to the
engine. Filter pin connectors should be located at the controller housing
interface and shunted to ground on the case. Filter pin connectors should have
40 dB attenuation, minimum."

Nothing on *how* the cables should be shielded, just a requirement to shield
them.

Ron Wanttaja

Ron Wanttaja wrote:

Nothing on how the cables should be shielded, just a requirement to shield
them.

That is better than some of the documents I've worked with. I wonder how
many existing engines would meet the standard as is or with minor
modification -- if the manufacturer were interested in a share in a very
small market. Back to the numbers game...


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