There's a definition of airworthy hiding in Part 3.5: "...the aircraft conforms to its type design and is in a condition for safe operation." Conformance with type design essentially means conformance with the TCDS, which is generated and maintained by the manufacturer or TC holder, and conformance with applicable STCs and relevant ADs.
There's a lot more to it than the TDS. Dan covered it pretty well. The type certificate is issued based on the manufacturer's demonstration that the aircraft meets all applicable standards (CAR 3, FAR 23, etc).
Yes. Conformity with the TCDS is required in order to be airworthy.
Part 23 governs design and certification. It’s not relevant to us mere pilots. But it may be an interesting read for pilots who are gearheads.
It absolutely is relevant when it comes to discussion of airworthiness. That's why one of the entries you will find in every TCDS is the "Certification Basis" which tells you exactly which of those certification regs is incorporated by reference into that TCDS. Without knowing what aircraft the OP was flying, we don't necessarily know whether 23.1145 was in effect for that airplane, but chances are if not there was a similar reg.
Another thing that's incorporated in later aircraft is the documentation, that is, the POH/AFM for that airplane. What does it say about operating with a defective ignition system?
With that in mind, the FAA does not decide whether a defect in an ignition system renders an airplane unairworthy, at least, not in the way that I think you intended (and I know you'll correct me if I'm wrong). Should the issue come to their attention, they will refer to the TCDS, STCs, ADs, etc. to determine whether the defect results in non-conformance with the type design.
You're correct that it's not *just* the FAA in a vacuum, the manufacturer has a lot to say about it as well, all via official documentation of course!
So yeah, the regs in the Certification Basis, the engineering and production documentation, the POH/AFM, all of that "paperwork that weighs as much as the airplane" is all relevant here. The FAA makes the rules, the manufacturer states how they're following those rules, the FAA puts their stamp of approval on it. The FAA doesn't directly say "That airplane must have a fully working ignition system to be airworthy." The FAA says "According to the manufacturer's documentation that we approved, the airplane must have a fully working ignition system to be airworthy." It is *NOT* up to the PIC/CFI whether the aircraft is airworthy or not, unless they've based that decision on all of the appropriate documentation - There does exist an answer in black and white on paper, it is not up to the judgement of the PIC.
As we all know, the responsibility for determining the airworthiness of an aircraft for a given flight operation falls on the PIC, ref.
91.7 and
91.3.
It is their responsibility, yes, but it is not their judgement. It is their responsibility to look at the appropriate documentation to make that determination.
Title 14, Code of Federal Regulations. Usually referred to in the industry as "14 CFR" or more informally, "the FARs."
In particular:
§ 3.5 Statements about products, parts, appliances and materials.
(a)
Definitions. The following terms will have the stated meanings when used in this section:
Airworthy means the aircraft conforms to its type design and is in a condition for safe operation.
Some years ago, a squadron CO of mine got bent out of shape when the Admin officer posted a bunch of "Safety is our Number One Priority!" signs around the spaces. The CO made it very clear that in fact getting the mission done was our number one priority. Safety was integrated into everything we did, with risk identified, removed, mitigated, or accepted as appropriate. Safety cannot be the number one priority in aviation, because it is inherently hazardous and we'd never leave the ground.
Yep.
