C90-12 in 7AC

[BeaverBill]

I have recently acquired another project. This is a 7AC that has been undergoing restoration for some years now. Part of the package is an overhauled C90-12F. The airframe has always had the original A-65 on it up to now. I know that Service Letter 56 allows for the installation of a C90-12 engine to convert the plane to a 7EC. However that appears to involve replacement of a considerable amount of airframe tubing. Another Service Letter allows converting to a 7CCM but specifies a C90-8 engine. I didn't find an appropriate STC in the FAA website. I would think that over the last 70 years or so, more than a few Champs have been reengined with the -12 series engines. Not difficult to do, but how to make the paperwork fly, is my question. Anybody have any guidance or suggestions for me?
Thanks for any help.
Bill

[Paul Agaliotis]

Bill,
Continental doesn't really specify any difference in the -8 or -12 engines. They consider them both C90 series engines, the -8 with no PROVISION for starter/generator and the -12 with starter/generator INSTALLED. So by removing the starter/generator and installing the factory blacking plates you end up with a -8 engine with provisions for starter/generator. Should you decide to add these items it then becomes an airframe modification for the starter or generator system.
The first paragraph in the Service Manual covers the engine models.
Paul

[BeaverBill]

Paul, Bob, and John, thank you all for your input. I did call Bill Pancake and he says that he should have his STC for the installation of a -12 engine in the 11AC Chief very soon. He has had a verbal approval from the FAA and is just waiting for the final paperwork to show up. He is working on the STC for the 7AC and hopes to have it in hand later this year. His approval will allow the installation of a C90-12 in a Champ either without electrical equipment, or with a lightweight starter and alternator. Just exactly what I was looking for!
Bill

[rkittine]

Good news Bill. When I talked to Bill about converting my C-90-8 7CCM to the -12 he told me that there was no service bulletin allowing nor any existing STC and that the Feds has told him that even through continental did not see the two very different (if the accessory case was blocked off) the extra weight and moment had not been approved for the 7AC. I wanted to put a C-90-12 in my old Chief and have been waiting for Bill to get his final paperwork.

Good luck - Bob

[Paul Agaliotis]

Bill,
The published weight for the A65 is 170lbs. The C90 is 188lbs including the starter/generator, removing them saves 26lbs, making it a loss of weight by 8lbs. In most cases the ASI work on opinions, not factual information.
Paul

[rkittine]

Paul, I know you have a lot more experience than I do. The Field Inspector of the Albany FSDO, one of the most lenient that I have found, would not allow the change and I confirmed that with Bill Pancake. So I kept conservative. My understanding is the the C-90-8 is even lighter the 65 because in addition to Cam, Carb. Jets and Prop, there is an increase in displacement to get the added horse power, which comes from boring (removing metal and weight) from the cylinders. The -8 also has different mags, tack etc. as the gears are not reversed in the accessory case.

Bob

[clipperfixer]

Wouldn't the easy way out be to get the STC from Don Swords and make the c90-12 engine into a -8? I know it would have to come apart and all, but it would give him a -8. I didn't get a warm fuzzy feeling about putting a c85-12 on my Champ using the service letters and eventually found a -8. After some of the most ridiculous stuff the FAA has been picky about lately I don't know if I wanted to deal with it should it become an issue. I know there are STC's for the Champ that allow the -12, but I opted not to use them.

[rkittine]

Not sure how you would make it a -8 except by covering up the accessory holes on the accessory case, which is part of the engine. Don would be the guy to call though. I had his Dream Machine C-85-12 conversion in my Chief and talked to him about a C-90 for my Champ seaplane, but did not know he had an STC for that. He is a great guy to deal with.

Bob

[Paul Agaliotis]

Bob,
I would consider the removal of the starter/generator a minor engine alteration. The gearing is turning reverse from the -8 but this only comes into play when you're replacing parts or overhauling the engine.
I don't know about the conversion of a -12 to a -8 but this might cause confusion from somebody that's not familiar with the engine and orders parts using the data plate information.
I wouldn't shoot down an Aeronca that had a C85-12 installed instead of a -8. Unless, the starter/generator was installed with no approval information. If Continental says the C85 series are the same, regardless of dash number, it's good enough for me.
Paul

[bob turner]

There are a couple of ways to look at this stuff. First, carefully study the definition of minor mod. Next, find the Continental bulletin that allows conversion of a dash 12 to a dash 8. Note that the bulletin says it is FAA approved.

Finally, make up your mind as to how you wish to regard this stuff - you can interpret everything the FAA says in the most restrictive way possible (most folks) or you can read the words in a way that makes things easier for you. I choose the latter, but I also try for field approvals, and once in a while I get them.

Remember, if you ask the FAA for an interpretation of their rules, you will get the absolute tightest interpretation. They do not want you to do anything. Apparently, they have been told that they are personally liable if they say anything that could be interpreted as permissive. I can no longer even get tower folks to discuss stuff with me.

[rkittine]

Bob,

I certainly agree. Since until recently I was flying under LSA rules and since I have a considerable amount of assets, I keep all my aircraft 100% signed off by the FAA. Can not afford to have an accident with a 70 year old airplane, hurt someone and during an investigation have them find that something is illegal or iffy. For that reason I am overly careful.

Bob

[bob turner]

Insurance and liability - one of my favorite subjects. Most pilots, and almost all instructors, know very little about it.

I spend time making sure that every time I move, either as an instructor or as a pilot, I have reasonable liability coverage.

If I cannot afford to buy a customer's airplane, I insist on a waiver of subrogation or indemnity for the value of the hull.

However, in California, if there is some flaw in your airplane that the feds find objectionable, it has to be the cause of the accident, or your insurer is simply forced to be there for you. If the flaw is a -12, and your gascolator falls off, it will be tough for a reputable insurer to deny coverage.

[clipperfixer]

For those that don't know it, Don has an STC to convert the -12 to a -8, I believe it covers all 4 cylinder continentals. The STC number is SE01592AT - To modify C-Series crank case from -12 to -8
and the information can be found here:
http://turnertech.wix.com/donsdreammach ... ntact/con8

I am not going to put words in Don's mouth, but basically you send the case out to him, he drills and taps and installs studs at the rear of the case to accept the -8 rear housing. I assume paper work is issued and again I assume the date plate is changed. So, it is not a doctored up -12 rear case, you will need the -8 rear housing and associated gears to go with it. I believe there is an oil passage that is plugged as well. I was going to do this and get his STC to turn a o200 case into a C85 case but I was able to source a C85-8 case so I went that way.

[rkittine]

I fly on a regular basis with a guy who is a CFI, an Aviation Attorney and who has been sued by the survivors of a fatal crash of one of his students definitely not his fault. He was also cited by the FAA for doing spins without parachutes, when the FAA guy challenged that the student was in fact doing spins for his CFI (he hadn't even soloed yet). I have been sued, once for a multi-engine student who died 5 years and about 1500 Multi-Engine PIC hours after he got his rating and also have been sued for something else that the judge determined was a "Frivolous Lay Suit" after I had run up $58,000 in legal expenses to defend myself and found out that the person who sued me had nothing and to counter sue would just cost me more money. Today I carry tow umbrella policies that cover me for $10,000,000.00 for both Criminal (some limitations) and civil (100% coverage) law suites, because we live in a litigious society. All my planes are in LLCs, but that does not protect the pilot from being sued for negligence, correctly or not.

I also learned, when I ran a commercial ammunition manufacturing company, that even with signed release from the consumer / customer, it meant very little and even when you won, the costs to defend were ridiculous.

Best to have no assets and very shallow pockets!

Bob

[Dennis]

I was told, generally speaking, that one can not contract away liability. As you say, a signed release of liability is not a guarantee.

Dennis