Continental engine coversions

[Glenn]

I sent my copy of Continental Service Bulletin to Dave Rutherford today. Hopefully he'll have it posted to the Mite site soon. It's everything you'll ever want to know about how to convert one model engine to another. It's my belief that most Mites came from the factory equipped with A-75's with a 65 dataplate. I have yet to tear into one that hadn't had the 75hp parts in them already. My guess is that Continental continued to use the 65 parts until they ran out. Many manufactures use 'WEU' in their parts catalogs which means, When Exhausted Use, and it's the latest model part. How many times do you call into a parts supplier and give them a part number only to find that it's been superceded? More common than not.

The best part of this service bulletin is on page 3 where you are instructed to send your old data plate back to Continental with a check or money order for $1.38 and they send you a new data plate. That would hardly cover postage today!

Hey Scott, I'm back.

[Dave Rutherford]

Okay, on the Maintenance Page there are now three versions of Continental Service Bulletin M47-16, dated 12-30-47, available for downloading as PDF's. Here are the links on that page:

Continental Engine Service Bulletin M47-16, 12-30-47, plus Supplement No. 1: 6-7-48 (pdf) [14 pages - two missing]

Continental Engine Service Bulletin M47-16, 12-30-47, Rev. 7-9-52 plus Supplement No. 1: 2-26-60 (pdf) [17 pages]

Continental Engine Service Bulletin M47-16, 12-30-47, Rev. 9-26-68 (pdf) Procedure and instructions for various engine model or series conversions. Applies to the A50 4 thru 9, the A65 1 thru 9, the A75 8, 9, & 12, and both C75 & C85 models 8 & 12. [16 pages]

My thanks to Glenn for helping me to figure out what they all mean.

[Joelj]

Gil Gibert put me in touch with Mike McCrath - a Mite owner in Seattle who responded to me with the following e-mail:

Yes, I do own a Mite, a 1953 model, and it is equipped with a "337-approved" Continental A75-8. It also has a Flottorp prop, which was mentioned in the approval. I happened by my engine during a rebuild of the the plane's old A65. I decided that, since I was going through the rebuild process anyway, I might just as well bring it up to A75 specs. As you are probably aware, the A65 and A75 are the same engine; it's just that the latter has certain internal modifications that allow it to run at a higher rpm where it picks up the extra ten horsepower.

I've found there are certain advantages inherent in the A75. Although it has no effect on rate of climb (that would be more a function of torque, horsepower per RPM and prop pitches), at 2300 RPM cruise I do realize about ten additional miles per hour at any altitude. Of course, it burns bit more fuel at that setting, but the true advantage is realized where one is given more options in juggling fuel v. speed to the "mission" at hand.

I was able to get my approval simply by showing the FAA rep similar paperwork from another Mite. That was enough to convince him that 1) it had been done before, and 2) it was feasible. The only small problem I came across was with the prop. The 337 I presented them described a Hartzel unit and, since each of these field approvals is unique and specific to a single airplane/engine/prop combination, I had a bit of a knot to untie getting approval with my old wooden Flottorp club in place. That particular issue should not materialize in your case, however.

If you're interested in my sending on the 337, I must first say that I possess no way of scanning my paperwork via e-mail, and fax usually turns out too "dirty". However, if you don't mind a few day's wait, I can surface mail photocopies to you. You'll get good, clean copies that way, with no chance of the odd smudge being mis-interpreted.

Let me know.

All the best,

Mike McCrath

Mike is mailing me the "approved data" and I am confident it will allow my approval to sail through. Once I get it, and with Mike's approval, I will scan the 337 and offer it up to Dave to post here on the site.
Thanks to all for the help - we Mite owners and lovers are certainly a great bunch of guys if I do say so!
Regards,
Joel

[Keith Mackey]

Joel:

It appears that you are on your way to solving the problem. The 337 form from Mike will be a big help toward getting your installation "legal" through the field approval process..

There may even be a simpler way of solving the problem. A quick review of the Continental SB M47-16 that Glenn just provided to this web site reveals that the differences between the A-65-8 and A-75-8 is primarily the pistons and rods. The crank and valve guides are clearly backwards compatible, and I'll bet if you do some research, you'll find that the pistons and rods are also usable on an A-65. So, I think you'll discover that your engine can legally be called an A-65 by only changing the ignition timing back to A-65 specs from the A-75 timing described in the Bulletin, even though it has upgraded parts. If your A.I. agrees, you could just change the timing and the data plate back to the A-65 plate and only make an engine log entry noting the change in timing and data plate to comply with A-65 specs (gray area if a 337 is needed) and be legal. You'd loose your bragging rights on the extra power and no flight manual supplement or 337 for the airframe would be necessary. As far as the prop, the statement about any propeller that has a static rpm of xxxx from the TCDS A-803 should cover you with a log book entry stating that your installation meets this requirement. This would be the easiest (read cheapest) solution to the problem.

Should you elect to go ahead with a field approval, I recommend you download the new Advisory Circular AC43-210 (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/31bed1c77a32c64886256e43006da997/$FILE/AC43-210.pdf) that describes the process. Read this over before even beginning the approval procedure, and you'll probably know more than anyone else involved. Forrest Lovely reminds me to be sure and call your attention to the role of the DER as described in the AC noted above. All a DER can do is make the data "Approved Data" which then may or may not be approved by the FAA inspector you are asking to approve the particular Field Approval. The Field Approval Advisory Circular 43-210 states on page 7 what the DER can and can't do.


Let us know how you make out.

Keith

[Joelj]

Thanks to Keith and Glenn for all the help and insight. I got a call from Mike this morning and as it turns out, he can't find his 337. Seems he had to change mechanics right in the middle of his engine swap and he's not sure who has the 337. I'll keep you posted on the outcome.
Joel

[Keith Mackey]

Just order the FAA records on the aircraft and you'll have the 337 if it was ever filed with the FAA

[Gary Blevins]

I have just agreed to purchase Dick Ranks' Mite. While reviewing his paperwork I discovered he had a A75-8 with a Flottorp prop and no legal documentation. I think that's what got this conversation started in the first place. So I too would like a copy of that 337.

Gary Blevins