STC to install 540 in a Comanche 180

[Jim Golden]

Hi everyone,

I've been looking at lots of Comanche's for sale online. I want a six cylinder. But, I've noticed that there are some nice 180's advertised right now for very cheap. Many for $20K less than a similar condition 250 goes for. There was a local guy here who tried to sell a 180 a couple years ago. He finally parted it out. He said he even lowered the price to $12K and nobody wanted it. A shame, really.

Since Piper used the same prototype for testing behind both the O-360 and the O-540, and everything I've read said that the 180 and 250 are basically identical except for firewall forward, there realistically shouldn't be any major headaches with doing a swap like this.

Has anyone other than the factory installed a 540 in a 180? Is there an STC for it?

Was just curious. Physically, it shouldn't be a big deal at all. Legally, it might just not be worth it. I already ran into that with my new design for the stabilator parts. FAA and the DER said it would cost over $100K for the STC. Easier to just buy the Aussie horn.

But at any rate, I was wondering about the engine swap.

Cheers,
Jim

[Clarence Beintema]

It had been done in the past, but I can't imagine that with the current value of factory 250 models versus the cost of all of the parts required that it would be economically feasible.

Clarence

[Don Ostergard]

Another thing to think about is fuel capacity. Most if not all 180's (and all early 250's) came from the factory with 60 gallons fuel capacity. 60 gallons was just fine for a 180. Many early 250's (my own 250 included) were upgraded to 90 gallons via the tip tank route. 90 gallons soon became standard for 250/260's. While I will maintain that a throttled-back 250 is nearly as economical as a 180 - what's the point? One wants the extra power to get out of a short strip, or to bust up through an icing layer etc. etc. A "60 gallon" 250 flown at normal "250 hp" power settings would have a hard time meeting legal IFR reserves on a flight of any meaningful distance.

A 180 Comanche flown at economical power settings can fly a long way on 60 gallons. (I know of a 180 that has flown around the world - probably the perfect plane for such an endeavour.) But to convert a 180 to a 250 AND to make use of the extra power one will always wish one had also upped the fuel capacity. And that will cost big bucks.

Don Ostergard, ICS 3263
c-flhv@magtech.ca

[Michael Bryant]

Jim,

I am no expert, but I think Zach Grant has addressed this before. I am sure you can find his earlier replies using the search function.

IIRC though, he indicated no STC was needed but could be done with a 337 since the Type Data Certificate (TDC) listed the different engines. To make the switch, you would need to take the TDC and change ALL components marked as 180 and change them to the part required for the 250/260. I think it was pointed out that it is cheaper to just buy a 250/260.

Michael

[Jim Golden]

Thanks guys. Just another of my "crazy engineer ideas" coming to light. Like my newly designed stabilator horn/torque tube assembly that the FAA shot down because it was going to cost over $100K to do the STC....I'll give up and just buy a 250/260.

Of note, I did speak to David Johnston of Johnston Aircraft Service on Friday for nearly an hour. What an awesome guy! He knows about everything about these birds. Well, he laughingly told me that there "is" an STC out there to do just what I'd proposed: However, what he had done was to install a 180 in a 250 and go the other way for a customer that just had to have it. But, somehow, the FAA got it messed up and wrote up some paperwork that they'd gone from the 4 to the 6 banger. Anyway, there is apparently some kind of "ghost" STC in paper only...but it wasn't done.

On the other hand, he told me of a few cleanup tricks he's done to his own 260 and it'll cruise at 205-207. Now that's enough to make the Beech guys jealous

Jim