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How do builders get a warranty on parts they buy, and how do they ensure airworthiness when finished?

I keep some spare avionics on the shelf, for a rapid exchange if needed, to keep downtime down to the absolute minimum. The issue is that by the time I install a part, the warranty on it is long expired and the vendor washes their hands of it even though it is pretty obvious it was duff when I got it

From what I’ve seen, most builders take years to finish a build (actually the majority don’t finish and sell it on part-built) and it occurred to me that none of these people will end up with a warranty on anything, for the same reason.

Also how do builders avoid the engine filling up with rust? And the avionics being obsolete. The obvious way is to finish the airframe build before buying the engine and avionics, but from what I’ve seen this is usually not done I recall one project where the gap was over 20 years.

Shoreham EGKA, United Kingdom

Peter wrote:

And the avionics being obsolete. The obvious way is to finish the airframe build before buying the engine and avionics, but from what I’ve seen this is usually not done

Actually, some do – for example for Garmin you could by just an installation kit. If by the time you finish the plane the avionics are no longer manufactured, then you could by a new kit, small fraction in terms of cost! :)


By the time you finish the build the pilot becomes obsolete in terms of medical, rating & currency

Paris/Essex, France, , United Kingdom

Given that they have a builder versus consumer mindset, I don’t think warranty status on bought components is high on most homebuilders list of concerns. This may be changing as kit built aircraft take over from scratch built homebuilts, and when somebody cares about the issue they likely try to order the parts on a just in time basis.

Some homebuilts are flown initially with basic panels and used engines, then upgraded over time once flying. These are relatively short term activities when compared with building the whole plane and getting it flying. A guy I know just finished a compete mostly Dynon panel upgrade on his RV-6, a plane that he finished building 20 years ago. It took him probably 250 hrs of labor over about a month, working 7 days a week, but the stuff didn’t sit around very long before installation.

A detail oriented friend of mine built a particularly nice RV-7 that has numerous nice modifications, improved landing gear integrated into a modified engine mount being the one I particularly like. It was an extended project and took about 7 years IIRC, while the new O-360 Lycoming sat in a crate waiting (his employer had bought and given it to him as a bonus one year). We wondered about that as time went on, but the storage climate was dry and it’s been running well for the last 5 years or so.

Last Edited by Silvaire at 21 Jun 14:24

Peter wrote:

The obvious way is to finish the airframe build before buying the engine and avionics, but from what I’ve seen this is usually not done I recall one project where the gap was over 20 years.

Actually that is what most people I’ve come across do. They build the actual airframe then look for engine and instruments.

As for engine storage, this depends hugely how it’s been conserved and stored. Warranty of engines usually start once installed.

A surprising number of builders will sell off their built airplanes and go for the next. As for them, it’s not flying which is the hobby but building.

LSZH, Switzerland

Warranty of engines usually start once installed.

That’s a new one for me, especially in light of this. Lyco would mandate an overhaul if not installed within a year of their shipping date.

Regarding other parts, the situation, AIUI, is that if an A&P (or an EASA66 mechanic, or a “maintenance company”, or a “dealer”) buys the part, then the warranty can be arranged to start when they supply it to the final customer. But if a builder (or anyone of a lower rank, like me ) buys a part then the warranty starts running there and then. And IME the vendor always walks away from any idea of a delayed warranty.

OTOH, I recall from Garmin posts on some US sites that Garmin do special deals for builders, like shipping a part directly which is normally impossible to get except via a Garmin dealer (e.g. a GTN750), so they might do some special warranty concession. When I asked for more details I got … silence

Shoreham EGKA, United Kingdom

For my RV-10, the engine warranty period starts running on the earliest of (a) when the engine is first started or (b) 24 months from when Lycoming ship it. It comes lightly pickled and sealed with desiccant and you are supposed to keep the engine sealed unless the desiccant changes colour. The engine is fitted quite late in the build, so it’s not hanging around for long, once fitted.

Most builders buy avionics as late a possible, because new products come out all the time and they want to have the latest kit (although I’d say the rate of churn has dropped off in the last few years). I’m not sure what the Garmin warranty actually states but, in the one case that I am familiar with, Garmin replaced an LRU that was found to be dud on first power up without any hassle, even though it was more than 12 months after the initial purchase. In this case, although the builder did all the work, he worked closely with the avionics vendor, and I think that helps.

EGMA / Fowlmere

Indeed, on my RV-7 build I won’t be buying an engine or avionics until I’m ready to install them. That point comes when the airframe is ~95% complete.


I think the mindset is a bit different. Avionics can always be replaced with the newest stash. Or simply use steam gauges which already are “old”, but never obsolete. Engines are a bit different though. Some build their engines also, or get an old one from a wreck, get an aftermarket rebuild etc. Most buy new, and the usual warranties are in effect. With ULPower and I think also Rotax, it must be run within 24 months. After that the warranty is gone, and to renew the warranty, some factory maintenance must be done at some “official” site. Or you could just pretend you have already started it and the warranty is gone a picked engine can stay good for ages and ages, but the factory cannot guarantee it will.

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