Anyone driving a HC-C2YK-1BF F7666A-4 prop

I have been using this prop on RV4 with IO-360 for last 1300hrs. Anyone else driving one of these?

I have one on my IO-360 A1F6D powered RV-8. What's up?

Seems we may have been a bit overzealous in pursuing the perfect profile when we cut it down from 74" to 72". Plane went in for some instrument work and I thought it be prudent to get the prop check out by certified prop shop since it was 6 years since last saw a prop shop. So asked them to do reseal. Appears it below Hartzell width limits at stations 30 and 34. All rest (thick and width at stations 12 18 24 are above limits). Checked original sizes and we actually cut it down below these limits originally so it been flying like this since "new" for 1300hrs?

Is it scrap or can I continue using it?

Have had hub and blades O/H (xray and inspect) and all other than above is serviceable to certified standards. Prop shop will not release it back to service since local experimental rules have changed recently (well rather local Authority's interpretation thereof) and they want Hartzell to issue OK letter? ?

Current installation runs away from "newer" CS offerings so I am loath to spend $7500 to loose a couple kts...

Any idea's or I may be forced to go FP which would be a shame since this aerie performs above vans numbers.... (even with the bumps and bruises associated with a hard working airframe)

Homebuilt Propellers

If your propeller is a homebuilt or experimental status, your propeller does not have to meet certified propeller standards, that being said you will need all
AD Notes complied with. 99 percent of the propellers on homebuilts are built using blades that do not meet standards by Hartzell, You do not have to ask their permission to fly something that is rating as experimental... We overhaul for homebuilts all the time and you do not need a FAA Statement.

Laurie Marshall
Western Aircraft Propeller 503-667-8865

Based on his location, I'm assuming he may have slightly different rules in South Africa...?

ZU-RVFour said:

Is it scrap or can I continue using it?

Click to expand...

Without knowing why Hartzell has specified those dimension limits it is not possible to know the potential consequences of flying with this prop.

Maybe those dimension limits are there to ensure prop performance, so type-certificated aircraft can make the performance that is claimed in their Aircraft Flight Manual. If this is the reason for this dimension limit, then there is no risk for you to fly with the prop.

Or, maybe those dimension limits are to ensure the prop remains harmonically similar to the basic design. If this is the reason, there may be a risk of harmonic incompatibility with your engine. If so, there would be a risk of cyclic fatigue and eventual failure of a prop blade. The resulting extreme prop imbalance typically leads to pretty much instantaneous failure of the engine mount and the resulting aft CG makes the aircraft uncontrollable, leading to a fatal accident. Note: the vibrations that cause the prop to fail are at such a high frequency that you cannot feel them. So, don't kid yourself that you are OK because it feels smooth.

Bottom line - no one on this forum can tell you with any certainty why Hartzell has specified this limitation. Only Hartzell can tell you that, and I doubt their lawyers will let them share the info. So, my recommendation is to scrap the prop. If the prop fails it will lead to a fatal accident. How much is your life worth?

That prop runs away from a 7447? I very much doubt that. I took the same prop (7666-4) off an RV-6a. When it went to the shop, it turned out to be a scrapped-pile put together prop from a bunch of old propstrike parts. Had to get a new -7447 and the 6a with no other mods at all picked up 3-4kts in cruise.