New sumps

[T. C. Downey]

To answer your question: Appendix A to Part 43 Major Alterations (v) installation of structural parts other than the type of parts approved for the installation. The sump of an 0-300 is a magnesium structure that collects the oil that lubricates the engine. To change it to aluminum is a major alteration that will require an engineering evaluation. This "opinion" is not based on some bureaucratic concern over the definition of the word "structure". It is based on the simple fact that you wouldn't want to modify something as important as a sump without making sure you are covering ALL THE BASES and producing a component that will be safe and reliable.

Continental made a few sumps from aluminum, it is not a change from type design.

Wy wouldn't a exact duplicate of the sump made from aluminum be safe and reliable?

[bagarre]

I don't think the concern is regarding safety nor reliability but rather what the FAA will approve

It shouldn't be very difficult to provide engineering data that shows the cast aluminum meets or exceeds the structural properties of cast aluminum. That data is probably already in the Engineering Handbook somewhere.

Aluminum is about 35% heavier by volume than magnesium so that might prevent it from being considered a direct replacement part. The installation may require a new weight and balance. It's not the end of the world but something to consider.

Are you thinking about this as an STC?

[voorheesh]

If Continental manufactured sumps made from aluminum, those specs could be used as approved data for obtaining a field approval for a one off of what you are trying to do. Is there a Continental P/N for an aluminum sump for an 0-300? If you want to produce more than one version and sell it to the public, I believe you will need an STC (and PMA) which will require engineering data including a drawing, specifications, as required to ensure the modification meets or exceeds Continental type design. To accomplish this, you would need the services of a DER and there should be a slew of them in your neck of the woods. This process, by the way ensures an acceptable level of safety and reliability. While it is fun to characterize the FAA and other aviation authorities as bureaucrats, the controls imposed are a big reason why we have such a safe system and can enjoy sixty plus year old engines and airplanes.

I realize you know far more about Continental engines than I do but this whole conversation runs against everything I have been trained on. Off the top of my head I can think of several obvious considerations such as resistance to corrosion, susceptibility to cracking, metal (heat) treatment, fastening, etc, etc that would require some careful analysis or definition. Continental probably has those studies. Maybe you intend to cover those bases, but your description suggests simply cast it, install it, and have any old power plant mechanic sign it off. I'm sorry, but I just don't buy that. Your idea has merit and would likely be of value to owners of these engines but you need to work within the system and, as they say, "do it right". Good luck and please don't take my advice the wrong way.

[T. C. Downey]

I first said that I would get PMA, so lets not loose our lunch over the sake Of an argument.
But first things first, the resounding lack of orders make this all a moot point.

[GAHorn]

The 0-300 sump is not a structural part, would the material change be a major modification or a minor?

Who declares airworthiness?

Surely you jest. Altering a type-certificated engine without an STC or an FAA-PMA (which may STILL require an STC for the modification) is certainly a major alteration.

I first said that I would get PMA, so lets not loose our lunch over the sake Of an argument.
But first things first, the resounding lack of orders make this all a moot point.

Tom, I doubt a few days of a question posted at this forum constitutes a definitive answer as to whether or not there is a lack of interest...or whether it's a moot point. There are simply thousands and thousands of these engines out there that might benefit from an improved/affordable sump. Don't give this up based upon this forum.

If you can get the part FAA-PMA'd, then that is a good thing and by definition that part would then be an approved replacement part..... and it would be a part which TCM not only doesn't provide.... it's one they might reasonably be expected to approach you about supplying to THEM for replacement support purposes. They already have re-entered the market on cylinders for this engine purely because Superior started making replacements.
You might get RICH... and then we'd all be telling stories about how we "KNEW TOM WAAAY BACK WHEN he was just one of US!"

Don't get discouraged. I like your entrepreneurship!

[T. C. Downey]

A couple things GA, what do you mean "IF" I get PMA. It's not that difficult. It is a manufacturing side of the FAA. They are not who most folks form an opinion about.

The folks that I have already talked to say that aluminum that has already been used by the OEM is not a major change, it is in fact no change at all.

PMA...... If you are manufacturing parts for sale you need one to be legal.

But I can make one for my self, I can sell you the model and you can make one for yourself, then you sell the model and so on.

OBTW, what makes you think this is the only place I have placed this idea.?

AOPA, The Cessna 172 web page and here has generated one order. in 3 weeks.