The International Cessna 170 Association

Anyone have a copy of this old SB M46-23. It's not available from Continental and a search of the web was not fruitful. I'd like to read it as it is suppose to say words to the effect that MMO is legal in Continental engines. I'm not holding my breath though as you'd think if this was the case M46-23 would be wall paper on lots of hangar walls.

I was unaware there was once a 73 Octane Aviation Fuel.

Interesting also that 80 Octane Aviation Fuel didn’t contain Lead. That gives me more comfort to use MOGAS.

Bruce Fenstermacher wrote:Anyone have a copy of this old SB M46-23. It's not available from Continental and a search of the web was not fruitful. I'd like to read it as it is suppose to say words to the effect that MMO is legal in Continental engines. I'm not holding my breath though as you'd think if this was the case M46-23 would be wall paper on lots of hangar walls.

Since that is not an “approved” document I doubt it makes the use of MMO “legal”. (But, I also believe an owner gets to do what he wants to his own equipment as long as he’s willing to accept any consequences.)

Interesting.

Not an approved document George? Certainly R. D. Hicks, Service Manager, Aircraft Engine Division, Continental Motors Corp., approved it. What makes it any different than a SB a Continental representative issues today on behalf of Continental?

A letter from a service mgr is certainly good information…but that does not make it “approved”. This document resembles anecdotal information (with regard to additives) more than it does “approval”. For example, no specific or named additive (such as MMO) is even mentioned, much less identified, tested, or approved by anyone…neither the engine mfr’r or the certifying authority, (probably CAA back then), and not FAA, It does not meet “approval” in the traditional sense. (Not much different than the “wing substitution letter” from Cessna which you posted.

Great info, from Cessna on Cessna letterhead,…but Not approved.

What makes it different? An example of a Continental technical document that is “approved” in the sense intended would be so-marked, such as the Ovhl Manual, or SBs,

IA DPE wrote:I was unaware there was once a 73 Octane Aviation Fuel.

Interesting also that 80 Octane Aviation Fuel didn’t contain Lead. That gives me more comfort to use MOGAS.

I’ve never seen anything lower than 80, but my Dad’s Stearman was placarded for “73 Octane or Higher”.

I think the current M-0 Continental Maintenance Manual would take precedence over a Service Bulletin from 1946. In section 3-3 the Continental Maintenance Manual says,

We often receive inquiries regarding the potential use of alternative fuel and oil additives and/or concentrates (formulated primarily for automotive and industrial engine applications) for use in our aircraft engines. Most of these additives and concentrates are not compatible with air-cooled, light aircraft engines in their operating environments. With the exception of the use of isopropyl alcohol or diethylene glycol monomethyl ether (DiEGME) compound (described in the following paragraph), we do not recommend the use of additives or concentrates in any of our aircraft engines. The use of unapproved additives may void the engine warranty. Use only recommended fuels and lubricants.

I see that back in 2014 Continental Motors Group was involved in a study of CamGuard. I assume they found no benefit as Continental is not recommending the use of CamGuard.

Regarding the lack of "FAA (or CAA) Approved" statement on SB M46-23, I doubt any manufacturer included that on their documents prior to 1958. We discussed this here. The late Bill O'Brien -- the FAA rules guy -- wrote, "The manufacturer’s maintenance manuals, service bulletins, and service letters have always been regarded as a source of acceptable data for complying with 43.13(a)(b) ... ." (Nuts and Bolts: A Newsletter By Mechanics for Mechanics, Issue 08-03) Now one could debate "acceptable data" vs. "approved data" here.

Further reading on this subject is found in chapter six of AC20-176A and the cancelled AC20-114.

“The Air Commerce Act was passed in 1926. This landmark legislation charged the Secretary of Commerce with fostering air commerce, issuing and enforcing air traffic rules, licensing pilots, certifying aircraft, establishing airways, and operating and maintaining aids to air navigation. “

https://www.faa.gov/about/history/brief ... navigation.