I have a question - my apologies if its obvious or has been answered before - I did do a little searching but didn't see what I was looking for. My question is:

How do you read a TCDS to determine if a modification requires an STC or 337?

The reason I ask is that I am curious if a Maule M4 engine can be swapped from the O-300 to the IO-360. I've searched the maulepilots forum to see if there are STCs or upgrade and I've found comments stating that the IO360 is in the TCDS, but I don't see that. I see all the different models up through the current ones -and I would have thought that you'd have to have tons of paperwork to switch out engines/props etc listed between any model, but I've seen people claim that the IO360 or the frank 220 is on the TCDS so no paperwork is required. I wonder why/how that is? Can you swap engines between "major" designators? Like can one upgrade an M4 to any other M4 (but presumably not to an engine on an M5)? How do you read these things?

I've found the relevant TCDS here:

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/c46c1c3d2a5a4811862579dd007b3e02/$FILE/3A23%20Rev31.pdf

But it appears to me to have every maule model since the beginning in 1 doc. When I read the specific section on the M4, it only lists the O-300 A or B:

I. Model Bee Dee M-4, 4 PCLM (Normal Category), Approved August 10, 1961
Model M-4, 4 PCLM (Normal Category), Approved February 21, 1963
Model M-4C, 4 PCLM (Normal Category), Approved October 7, 1965
Model M-4S, 4 PCLM (Normal Category), Approved March 15, 1966
Model M-4T, 2 PCLM (Normal Category), Approved March 15, 1966
(M-4 same as Bee Dee M-4 except for minor changes)
(M-4C same as Model M-4 except for modified right fuselage truss, larger rear doors to facilitate cargo loading, and other
minor changes.)
(M-4S same as Model M-4 except for minor changes.)
(M-4T same as Model M-4C except no rear seats or rear door and other minor changes.)
Engine Continental O-300-A or B

And the next entry is for the M4-210c:

II. Model M-4-210, 4 PCLM (Normal Category), Approved September 24, 1964
Model M-4-210C, 4 PCLM (Normal Category), Approved October 7, 1965
Model M-4-210S, 4 PCLM (Normal Category), Approved March 15, 1966
Model M-4-210T, 2 PCLM (Normal Category), Approved March 15, 1966
(Same as M-4, M-4C, M-4S, and M-4T except for the installation of a Continental IO-360-A or D engine.)
Engine Continental IO-360-A
Rev. 31 3 of 48 3A23
Continental IO-360-D for s/n 1086C and up

Not sure if this helps, but lots of good info and #43 on this page may be what your looking for?
http://www.mauleairinc.com/pdf/modification_kit_index.pdf

Soy,

The TCDS starts out by giving the main specs for the airplane as it was certified. In this case it spells out the basic specs for the M4 airplane. I'm sure you got that part, I'm not trying to insult your intelligence. Then each specific variation is called out. I think what makes the Maule able to have the engine change is the way way that the TCDS is written

If you look at page 2 of the document that you shared the link to, it has the description of the Maule that has the IO-360,

II. Model M-4-210, 4 PCLM (Normal Category), Approved September 24, 1964
Model M-4-210C, 4 PCLM (Normal Category), Approved October 7, 1965
Model M-4-210S, 4 PCLM (Normal Category), Approved March 15, 1966
Model M-4-210T, 2 PCLM (Normal Category), Approved March 15, 1966
(Same as M-4, M-4C, M-4S, and M-4T except for the installation of a Continental IO-360-A or D engine.)
Engine Continental IO-360-A

It is the "Same as...." information that gives you the ability to move the engines around. Some TCDS will call out specific serial numbers that those configurations apply to and then you are hosed if your intended machine does not fall within those number. Then you need the STC or 337 to get an approved installation.

Hope that helps,

Paul

Thanks for the info.

It may be that your logbook entry/337 will read something like "Maule M4C converted to M4-210C" or something like that. Of course, then your airplane wold have to conform to the specs for the M4-210C, which might have the basic M4 structure beefed up somewhere (reinforcements on the engine mount, added ribs in the wings, larger vertical stab, or ??). Lots of 65 horse Aeronca 7AC Champs have had 85's installed, legitimized by "conversion to 7DC" (or whatever) paperwork & dataplate. It'd be best to get with a Maule specialist for this info, and/or have a serious sit-down with your IA & your local FAA inspector.
It might be easier to buy what's left of a wrecked M4-210 and repair it by installing your new used fuselage assembly etc.-- aka "you just can't keep a good data plate down".