I’m working on getting a field approval for converting an M4-220C into an M4-235C. Has anyone else ever attempted or accomplished this conversion? Also any thoughts? Thnks in advance and happy flying!

The Maule Mod Kit Index doesn't have this mod:

http://mauleairinc.com/pdf/modification_kit_index.pdf

In todays field approval environment, without something like this to back up the approval, I doubt it could happen. But you may be luckier than the rest of us.

It is an interesting combination but likely only possible through experimental.

Frankllin CA-350-C1 - 325lbs dry
Lyc O-540 B4B5 - 366lbs dry and i don't think any certified 540s are lighter??

At best you have 41 lbs more weight up front to deal with. Even more if you go higher horse power. How does this work with your weight and balance calcs? Prop is -60" arm and engine is ~-40" arm.

With enough light weight components and $$ you could end up with a 540 and not be much different in weight (maybe even lighter) or cg location than a franklin arrangement but probably not without being experimental.

There is one. It was done by BD and it's on the TCDS and it's still flying.

I did several weight and balance calculations and no matter how I loaded up I could not get the CG out of the forward range. Even with 2 pilots weighing 200 lbs each, minimum fuel, and no bags it came out to be in the range. My ultimate goal would be to install a light weight CS prop to make up for the added engine weight.
I sure would like to chat with the person that has done this crazy thing before and see how it flies!
Thanks guys!

A composite 2 blade prop will give you 15 of those lbs back at the farthest forward CG location. That should equate to a lot of leverage in the calculation.

Along with the composite prop as pointed out by DeltaRomeo, composite spinner -2lbs, lightweight starter, lightweight alternator, CF cowling -10lbs, and if your battery is on the firewall, go with a lightweight battery or move it rearward. It could add up to as much as an additional 30 lbs off the nose.

Along with the composite prop as pointed out by DeltaRomeo, composite spinner -2lbs, lightweight starter, lightweight alternator, CF cowling -10lbs, and if your battery is on the firewall, go with a lightweight battery or move it rearward. It could add up to as much as an additional 30 lbs off the nose.

If the M4-235 is listed on the Type Certificate Data Sheet you don't need a Field Approval to install the engine. I went to the FAA website and looked up the Maule TCDS 3A23 and didn't see a M4-235 listed. I didn't see anything listed in the registration data base either.

I didn’t see it on the TCDS or the Maule modification list. I’m moving on with the field approval! I’ll keep you all posted

Keep us informed on the process. When I looked into an engine change the local FSDO said it would have to be done on the STC process.

Cekberg,
Have you talked to your FSDO? Have they indicated that they are open to considering a field approval for this?

Haha that’s funny, I just got my email all drafted with the attachments and suddenly realized the FISDO was closed! I guess I will wait...

Inspectors put back to work today. Without pay so might be a little cranky.