https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_20-188.pdf This looks like a gift to product liability attornies. STC makers are absolved and installers are on the hook.

PapernScissors wrote:https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_20-188.pdf This looks like a gift to product liability attornies. STC makers are absolved and installers are on the hook.

Seems to be somewhat reasonable though, right? Perhaps a gift to defense attorneys? If I'm a STC owner/holder or manufacturer of a STC'd part, and the installer does a bonehead job installing it for whatever reason, or their unique configuration with other STCs presents an incompatibility I haven't explicitly addressed in the paperwork, shouldn't that be on them?

I just looked at a STC issued in 1982 which has the compatibility of multiple modifications statement making it the installers responsibility in the limitation and conditions paragraph of the STC so this part is not new. What is new is the AC which attempts to identify areas where compatibility conflicts could arise.

Tim

Agreed...

The STC compatibility issue is not new. The AC has addressed further helpful reminders and guidance. FARs are not modified, reintroduced and/or "re-interpreted" from what I read.

Looks to me that the biggest thing it does is provide examples of potential STC conflicts, but otherwise doesn't change much. As most of us do, I often read NTSB reports or summaries, and there have certainly been many incidents and accidents attributable to STC and 337 conflicts. As the owner of an airplane with multiple STC and 337 changes, it's something that my IA and I often have discussed in the past, whenever I've asked him to make a change. Indeed, some of the changes are exactly what the AC is addressing.

Cary

Cary wrote:Looks to me that the biggest thing it does is provide examples of potential STC conflicts, but otherwise doesn't change much. ...
Cary

From my perhaps imperfect read of the entire AC, the update now also includes a required signed statement of compatibility in the aircraft logs executed by the installer IA/A&P. Like you, I'm very sensitive to the unanticipated interaction of mods. However, the certification statement appears to be an open letter inviting a liability claim against the installer mechanic. I think those claims are probably uncommon (I don't think "rare" is the right word). The laundry list of incompatibilities is very vague. Perhaps the suggestion of having the STC producer install mods is the best solution to resolve that ambiguity. The most conservative strategy of owner/operators engaging an engineer look over each mod is a show stopper, IMHO.