02-21-2012, 12:03 AM
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 Re: Wi-fi in airplanes
> So show a Honeywell EFIS panel, FFS.
Yes, at least show something relevant.
There was a time when stock images or footage would be labeled as such.
Now they just put up "wallpaper" imagery that is sometimes relevant, and
sometimes not.
If you watch The Rachel Maddow Show, the staff is really into searching
out stock imagery used by politicians, often with hilarious results.
Back to aircraft, a part I designed er um had an issue. Let's put it
that way. It was used in the VOR vector circuit. Not every part had the
problem. The manufacturer had found a way to get the part to work by
inserting a resistor in an odd spot. I was harangued to approve this fix
by sales. It turns out the FAA allows (or so I was told) the addition of
passive components without requiring the device to be approved again.
This is insanity. I could add a cap in the right place and make
something oscillate that shouldn't, or stop something that should be
oscillating. Passive components can cause real problems.
When the manufacturer decided to visit the plant to put the fear of
Jesus in me, I arranged (with my bosses permission) not to be found, and
made the QA manager deal with it. What I did do is get permission to
drop my work and spend some time investigating what shifted in the
process to fix the problem, and I did a modification to the part. [Never
do a hack of a fix. Find the problem, analyze, and engineer.]
But the main point here is in theory they could add a ferrite here or
there to filter the wifi. Or physical shielding, stuff like that.
There should be no way for any RF in the cabin to interfere with the
aircraft. I have some parts out of a F-16's network that uses triax and
wide band transformers on the data bus. Obviously they wanted good
shielding and no ground related issues.
The problem with avionics in general is the integrator makes a pile of
money on the product, but the component manufacturer, at least in chips,
makes nada. The volume is low, the headaches are big. Custom chips is
another story, but COTS is the mindset of the aviation industry.
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