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Engineering Specs for General Aviation Aircraft

Engineering Specs for General Aviation Aircraft

Engineering Specs for General Aviation Aircraft

I have a fair handle on where to find general information and specifications for the commercial aircraft avionics systems I support at work.

I recently got a license and have been flying down the local airfield.

When I listen to discussions about similar systems on small aircraft, it's so different I really can't place what folks are even talking about sometimes.

I'd like to familiarize myself with engineering specifications for small aircraft avionics systems and their architecture. Anybody know of some good references?


RE: Engineering Specs for General Aviation Aircraft

Its changing so fast that few text books are available.  In the UK the LAA (Light Aircraft association) are running Avionics courses for home builders/GA pilots.  At these courses the displays, interfaces and wiring requirements are discussed.  See http://www.lightaircraftassociation.co.uk/Courses/avionics.html for a brief overview.

In the US the EAA (Experiemental Aircraft Association) have similar courses.

The benefit of non-TSOéd equipment is that modern PFD/MFD can be used with A/P, proximity info and coupled GPS/FMS systems.  So a modern homebuilt often has the same (or better) capability than a 10 year old airline - all at a fraction of the cost (typically $5k to $25k).

Garmin, BendixKing, Dynon all have intresting info on architechure and operation on their websites.


RE: Engineering Specs for General Aviation Aircraft


Aerodesign, please cite a homebuilt that can be built using "non-TSOéd equipment with modern PFD/MFD can be used with A/P, proximity info and coupled GPS/FMS systems", and cost out at $5000.00.

I wish to become a dealer immediately, as the world will surely beat a path to my door.


RE: Engineering Specs for General Aviation Aircraft

Go fly thruthefence.

Any homebuilt can have modern avionics starting under $5k.

My Europa, total cost of non-steam panel so far $2000.  7"MFD, it drives an A/P and takes Xaon XRX info.  Internal GPS.  Next stage is a Dynon D10A replacing the AI +$1500. This constitues a full EFIS at <<$5k.

Full refit is likely to be <$25k full twin 7"screens, XRX, Trig T21.

See www.dynonavionics.com, read the prices. No joke. See it work: http://www.dynonavionics.com/docs/SkyView_Video.html

Happy landings


RE: Engineering Specs for General Aviation Aircraft

My apologies, I missread your post; I thought you were referring to a complete package, airframe, powerplant, AND avionics, 'wheels up' for 5K. Big difference.

RE: Engineering Specs for General Aviation Aircraft

Thanks all.  It's funny, I know what it takes to retrofit the transponder system on a 757 or spec out an acceptable system on a 777, but how did they hook things up in the 172 I rent?  No clue.

So when the GPS initializes and displays a baro alt on the LCD, is it indicated, true, pressure alt, who knows?

It's not even be in the operating manual.  

Last weekend I took off in a Super Decathlon with my altimeter incorrectly set.  I saw that the XPDR was squawking an altitude that seemed more correct than what the altimeter said and realized what I had done.

It was a training flight (for a tail wheel endorsement) and we were doing patten work so it wasn't a serious mistake, but I got curious.  The CFI's description of how the system worked was probably correct but I couldn't understand some of what he was describing.  

I also think it's important to know where the transponder is getting it's Mode C altitude and how much error it has from True..  

I really love the business I'm in.  Discovering it first hand is probably the best thing I've ever done.

Of course the company only recognizes MBAs for promotion. The great herd of HR mullets always seems to validate like skill sets first and foremost.


RE: Engineering Specs for General Aviation Aircraft

It's from the encoder.

Maybe like this:
very popular model.

See the little nipple on the silver box in the link?
That is plumbed into the static side of the pitot/static system.  (or air data, for you big airplane guys). This thing 'talks' to the transponder, and the transponder 'talks' to ATC.

By regulation, when a shop installs an avionics package, there will be a supplementary paperwork package that includes the operation instructions (at a minimum) or a POH revision, if the subject aircraft requires such a manual.(not all do)The FAA Approved Airplane Flight Manual for Model 8KCAB, and it is required for this aircraft, will have a "systems" section (The POH revision for the encoder should be included here), a weight & balance section (showing the weight & location of the added components), and an "equipment list" (showing the model # & serial # of the equipment installed.) Also included in this paperwork package, are instructions for continuing airworthiness of the installation, such as inspection periods, tooling, special inspections ect. This paperwork package is considered part of the aircraft's permanent records, until the equipment is removed. Because this P.O.H. is required, per the aircraft's Type certificate data sheet, it must be complete, current, and in the airplane for legal operation.  

RE: Engineering Specs for General Aviation Aircraft

I have to assume it reports pressure altitude calibrated to sea level press of 29.92 in Hg?

What format does it use to send the information to the transponder?  Is it Gillham code?  In commercial systems we use ARINC 429 serial bus.


RE: Engineering Specs for General Aviation Aircraft

RE: Engineering Specs for General Aviation Aircraft

Thanks again.
This gives me a starting point anyway.

RE: Engineering Specs for General Aviation Aircraft

There's the annual Jane's series - not just "all the world's aircraft - the list includes an Avionics book.


To go back in time you might find back issues in a college/university library.

I have a 1990 issue that I got from the library discard pile.

Steven Fahey, CET

RE: Engineering Specs for General Aviation Aircraft

FYI, I just went to the GAMA site.  All of their standards are available for free download.


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