Experimental vs. Certified

[JackinMichigan]

Maybe this is not a proper question for this forum, but I am very curious as to what is the difference between certified parts and experimental parts. I see catalogs where an instrument will be 10x higher if certified, while the catalog assures me that they are exactly the same part.

I just ordered a tach drive cap to put on my IO-540. The guy asked me if this is an experimental or certified aircraft because the certified drive cap is a lot more??

I have asked this to knowledgeable aircraft guys and have never received an answer.

Thanks

[SmilingJack]

It all about that kittle "Yellow" tag

When I was looking at buying my engine the certified was $8000 more just for that little Yellow certified tag.

Now, its not always the case, but generally speaking when you have a very simliar part Certified vs. Experimental you will always save money by not making the manufacturer take on the liability they have when giving the Yellow tag Certified part.

[Kahuna]

paperwork.

[Mel]

Originally Posted by Kahuna

paperwork.

i.e. Gubberment Red Tape!!!!!

[JackinMichigan]

Hey guys... this is the same answer I get when I ask. Of course it is red tape and paperwork. Can anybody tell me specifically what hoops the manufacturer has to go thru to get it certified...

[SmilingJack]

The guys at Garmin can better answer this since they have both Certified and Experimental equipment.

But, Try to Certify a new Jet and it costs about $1B! Try to Certify a new part and it costs $100,s Thousands of dollars and 1000's of test hours.

All the "time" put into proving the part is reliable costs money...and the fact that after they prove this part that they now have gobs of liability if that oart fails they need more money to fight that failure in court....even if just to prove it was not their fault.

Comes down to Time invested and Liability. None of which the experimental market have to deal with.

[kamikaze]

"Can anybody tell me specifically what hoops the manufacturer has to go thru to get it certified..."

Depends on the type of part, but generally, you have to test and demonstrate (To some body such as the FAA) that the part is fit for duty.

For some parts, this could mean destructive and non-destructive testing, putting stress on the part (thermal, pressure, tension) and ensuring it will perform as advertised. Then it needs to be tested within the system it will be attached to. A part that seems just fine on its own can start behaving in unintended ways when added to a system (metal incompatibilities, vibrations, etc.).

For avionics, you have to meet a bunch of coding and development standards, on top of the physical things. Put your equipment through vibration, thermal testing and so on, but also ensure that code was developped and testing in a such a way as to ensure no (or very very very few bugs), with things like coverage testing, no unused code, unit testing, and keeping the system highly deterministic and sometimes hard real time.

There is a LOT that goes into certification, hence the costs. Some vendors will make the part that is certified (has the paperwork behind it to supports the fact it was tested and so on) available as uncertified part for a lesser price. but that part without paperwork for proof of certification cannot be installed in a certified aircraft.

For example, Van's sells certified and non-certified Lycomings. EXACT same engine, one with, and one without paperwork, the later being less expensive.

Note that one can follow certification-quality processes, tests, methods, etc. without bothering to PROVE it to the FAA. This is done with experimental parts ... I believe Dynon has stated for instance that they follow much of the same approach as for certified avionics internally, but just don't go the extra step of convincing the FAA that they did ... this can lead to high quality non-certified parts.

Other experimental parts manufacturers don't go that far ... that's what you lose in the experimental world ... you don't have the certainty that whatever you're buying was developed and tested thoroughly, to detailed and very high standards ... maybe they were, maybe they weren't. Good research usually helps you weed out the good from the bad, based on your own opinion and research ...

[sblack]

Another aspect is the record keeping. To build a certified widget, once you have done all the testing and documenting to prove the design is certifiable, you then have to prove that each individual widget you produce meets that design. So each batch of raw materials has to have paper work and perhaps test samples. Each production process has to be documented and records kept. At the end of mfg it has to be inspected to ensure it complies to the original design. And where the widget doesn't meet the original type design, because you ran out of bolt X and had to use bolt Y, you have document that and prove that it is the functional equivalent.

Also, and this is the big one, if you build your own airplane and you crash, YOU are the mfg, legally speaking, even if it was a quickbuild kit. So far, to my knowledge, the lawyers have not been able to go after the mfgs who built the parts, because the builder is supposed to determine their suitability of those parts for the plane. If that ever changes it will have a big impact on our sport. It might have happened in individual cases, i'm not sure.

We say that an airplane is certified when the weight of the cert documentation is equal to the weight of the airplane. That's probably not far from the truth.

[BobTurner]

Originally Posted by sblack

So far, to my knowledge, the lawyers have not been able to go after the mfgs who built the parts, because the builder is supposed to determine their suitability of those parts for the plane. If that ever changes it will have a big impact on our sport. It might have happened in individual cases, i'm not sure.

After the John Denver crash the companies that made and sold the fuel valve used were sued. I believe they settled out of court.

[BobTurner]

The answer to the oP's question of why certified parts are so expensive is simple: when only one source exists, the company can raise the price to just short of where a lot of people throw in the towel and walk away.

I still remember my 182 days, when TCM was the sole source for new cylinder assemblies. Then Superior began making them, and overnight the TCM price dropped to 1/2 of the former price. They just charge whatever they can get away with.