Changing Lycoming engine model number

[Jim K]

Pursuant to this thread:

FFS. I need a new hobby.

This ****ing airplane. Had a small oil leak behind the prop. Decided to wait for annual, assuming it was a crank seal. Mechanic pulled the prop and found the plug over the governor shaft loose & leaking. Same exact failure as 2.5 years ago. I was *n* hours from having a windshield full of oil...

www.pilotsofamerica.com

I'd like to take this "opportunity" to swap my IO540K1G5D for a K1G5 via the Aeronautix STC, doing away with the dual mag. Ordinarily I'd just make the swap with a Lyco fac. rebuilt, but lead times are ****ing stupid and I'm not going to leave my engineless airplane carcass to rot in a hangar for a year plus.

The G5 and G5D are quite different and not really convertible. However, the K1A5 (and possibly the K1E5, but i need to check the parts book) are the same as the K1G5 with the exception of the accessory case and a couple accessories. The question is, what's involved in converting between "dash numbers"?

I found SI 1304J, which covers getting new data plates. Is it as simple as swapping the accessory case, noting the conversion in the engine log, and calling up Lyco for a new tag?

 

[Bell206]

Is it as simple as swapping the accessory case, noting the conversion in the engine log, and calling up Lyco for a new tag?

No. Its considered a major alteration and you'll need approved data unless there is an OEM option. If it were me I would contact Aeronautix and discuss your ideas with them for options. Its their core business to alter aircraft. You could also contact Lycoming support to see if there is data on the conversion between models. Anything is possible with the right approach. Questions?

Lycoming model difference reference

The 540 TCDS give some more info plus lists similar data to link above.
540 TCDS

 

[Jim K]

No. Its considered a major alteration and you'll need approved data unless there is an OEM option. If it were me I would contact Aeronautix and discuss your ideas with them for options. Its their core business to alter aircraft. You could also contact Lycoming support to see if there is data on the conversion between models. Anything is possible with the right approach. Questions?

Lycoming model difference reference

The 540 TCDS give some more info plus lists similar data to link above.
540 TCDS

I am a bit confused. So ignoring the airframe/STC thing.... If I have a IO-540-K1A5 and I want to rebuild it as an IO-540-K1G5, that's a major alteration requiring a 337 and approved data? The engines share every part number except the accessory case, an extra gear, and the dipstick. Would the parts manual count as approved data?

 

[Bell206]

If I have a IO-540-K1A5 and I want to rebuild it as an IO-540-K1G5, that's a major alteration requiring a 337 and approved data?

Yes. A K1A5 and a K1G5 are considered variants to the original A1A5 with each variant receiving its own separate certification date as posted below. So each variant is technically a stand-alone engine similar to airframe variants. There are also variants where the original was a CAR 13 engine, and the latest model variant is a Part 33 engine that comes with its own ALS.

Would the parts manual count as approved data?

No. It is considered acceptable data. But I wouldn’t give up yet. It won’t cost you nothing except your time to inquire on what it would take to convert a K1A5 to a K1G5. Installing/converting different engine variants is more common than most people think. And if you want to make a serious attempt at this, I would definitely make the effort to at least see what it might entail to perform this.

K1A5 Cert date:


K1G5 Cert date: