Frequently asked:


Does the FWF package come with an installation manual?

Glad you asked: I just uploaded "Installation Tips for the First-Time Builder".   In addition to step-by-step details, it also covers background info on preferred materials and practices for the first-timer. More than 30 pictures; most are commented.  Find it in "TECHNICAL TIPS" on the Home Page

What about the gearbox - isn't that often the weak point? Is this design durable enough?

Well, YES...and YES.   the engine/gearbox has been sold into the commercial airboat industry for ten years and over a hundred engines have been shipped; only recently did we break into aviation.  The highest time airboat has over 5000 hours. It runs 10 hours a day, seven days a week with no maintenance. They change the oil every year.

Can’t break it!

The gearbox is way over-designed, with only one failure - when one customer put the engine in commercial service with no oil in the gearbox at all. 

AM13 / AM15 Aircraft Engines for RV-12 - FAQs

I got this question several times. One builder said he felt "caught between a rock and a hard place".

Here's my personal take on it:

Certainly, the reduction in value of the airplane (because it’s EAB) is real, but kinda subjective. 

I would suggest we consider two things:

1. First, it takes a lot of “reduction in value” to offset the significant savings in cost.with an alternative engine.

Also, the considerable added performance will mitigate that effect anyway. 

Let’s wait and see what the market says.

2. Personally, I consider my airplanes to be a hobby, not a cost-benefit-return calculation. I’ve known builders who think more about resale than enjoying the journey, and by and large they don’t enjoy the journey. I have a friend who built an RV-12, and rarely flies it because the cost of fuel and wear and tear on the airplane will reduce what he hopes will be a profit when he sells it.   Sad.

Personally, I think you’re caught between a rock and a soft place.

Just sayin’


Follow us through the year and see how the market responds. I hope you’ll be among the many who decide to join us! 

Good luck….and enjoy the journey!

What about the CG? I hear 30 or 40 lbs heavier than Rotax!....and which is it, anyway?

When I received my engine (May 2018), the whole package - dry weight plus all the FWF components (header/muffler/eng mounts/pumps/filters/cooling system/hoses/hardware/etc.) came out 40 lbs heavier than the Rotax 912ULS equivalent - and I said so.

Since then, Aeromomentum has re-designed multiple components to remove just over 10 lbs. So that's where the 30 comes from.

Actually, the comparison should be to the Rotax 912is - a similarly FADEC/electronic ignition/electronic injection engine - whose all-up weight is 20 lbs heavier than the 912ULS. So the real difference looks to be about 10 lbs for the RV-12.

Tell me about the AM15-HP versus the AM15....and where do you get that horsepower? Is that real?

First of all,  Aeromomentum blueprints every aircraft engine from a bare block.  From there  we build up and blueprint a racing engine using the near-bullet proof Suzuki  bottom end and appropriate after-market components from the off-road and racing community.  

Every component is weighed and balanced, oil galleries are radiused, cylinders are ported and flow-balanced, and even the valve seats are custom-contoured for maximum flow. To that we add a large intake plenum for equal air flow and both tuned intake risers and Helmholtz-tuned exhaust headers. 

The results shows up on the dyno - and yes, we dyno every engine. Each engine is custom-tuned for maximum performance and the broadest torque curve available, with careful margin against detonation at the highest power.

The principal difference between the AM15 and the AM15-HP is, among other things, a custom designed High lift/broad profile camshaft designed by Mark Kettering, Chief Engineer. 

The HP camshaft allows better intake breathing, so at the same 5800 RPM where the AM15 produces 117HP,  the AM15-HP produces 131HP. However, because the AM15-HP breathes better, the peak horsepower is actually at 6500 RPM - at 147HP!

Makes the RV-12 a hoot to fly!

Next FAQ (coming soon)

FAQ text