The International Cessna^® 170 Association

This AD just dropped a huge hole in the family budget. I have an Avcon conversion 360 A1A 180 Hp Lycoming with the CS prop and the bad hub. Does anyone know why there are two Avcon STCs? Mine is SA806CE. It calls for a 74" prop. The other Avcon STC conversion is SA749CE and is for the 360-A1A or the 360-A1B and calls for a 76" prop??? Why two, and can I replace the 74" with a 76" prop, and even if I can legally move up 2", do I want to? I see there is a Top prop 80" too?? (but over $8K) I called Hartzell and they have a reduced price (40% off) for one year after the AD date on both the replacement hub ($1400 after 40% off) and on a new prop. Looks like the budget will take a hit for an overhaul of $1400 Hub + $1977 labor = $3377 plus freight. Any other problems found a tear down will add to the cost. OR.... a new 74" prop for $5600. My old prop is 25+ years old. I am leaning toward a new prop. I am looking for advice from the group as what to buy. I was also told by Hartzell that the Alco Aluminum plant is on strike and if I place my order today for a new prop, it would be April or May delivery! I have read many of the threads on this great web site about props, and still don't know what to do. Any help would be appreciated. Gary
One other question... I cruise at 23" MP and 2300 RPM. I saw a thread where someone ran at 23" MP and 2400 RPM. What will that do to my airspeed and burn? I plan to try that combination next time a fly. Gary

The required eddy current inspection can be done on the plane if the prop isn't due for an overhaul. If it isn't broke why spend the money replacing it? On the other hand if you have reason to doubt its integrity........?

Watkins is selling a new one he might be able to hook you up sooner.

http://www.cessna170.org/phpBB2/viewtopic.php?t=3850

If your prop has ben overhauled before a few times the blades will be smaller, or if you have a pretty large nick they will get smaller at overhaul which might effect performance. In which case I'd be buying a new prop for sure. At 25 years without prior overhaul expect "other problems found a tear down" also. If you go with a new prop do you need to give back the old one as a core? If not the blades could possibly be sold to reduce your cost.

The one Watkins is selling is the 76" so that wouldn't work and the price I was quoted from Hartzel was cheaper. I will have to take a look at the over haul record of my prop, but I don't think it has been done for a long time. It is in good shape without any nicks. What does an ECI test run? I talked to my wrench guy today and he told me that it had to be done by a prop shop and the prop taken off the plane. ??? I have about 37 hours to go before I need to do anything, but the delivery lag (If I go new) might cause problems with our Oshkosh trip this year. I do not suspect the prop has any internal problems, but I hate a suprize. Thanks for the input. Hartzell did say they wanted the old prop to keep the parts off the market, "Thats what we are in busness for, to sell new parts.", I was told. GARY

The new A.D. is an inspection of the front hub and thus it doesn't have to come off. Mind you if the NDT guys won't come to you and a prop shop that's capable is not at an airport, its comming off.

I called Hartzell as well about this same conversion and prop that I have on my plane. They told me they had a couple come apart so they put a A.D out on it. All the prices were the same as you guys heard, but a 100 hour inspection is now required from the prop shop. The cost is $150. and they dont have to take it off. Now its ready for another 100 hours. They are looking for any cracks in the hub.

Bill

As I said in my original post on December 7th.
" I have an Avcon conversion 360 A1A 180 Hp Lycoming with the CS prop. Does anyone know why there are two Avcon STCs? Mine is SA806CE. It calls for a 74" prop. The other Avcon STC conversion is SA749CE and is for the 360-A1A or the 360-A1B and calls for a 76" prop??? Why two STCs, and can I replace the 74" with a 76" prop, and even if I can legally move up 2", do I want to? "

I still don't know if I can use a 76" prop on my conversion.??? I read the Avcon STC and it states that "maximum prop size a 74". I have decided to go with a new prop and want to get the best performance out of the 180 hp. George, do you know if I can use a 76" prop? What would I gain and what hoops would I have go jump through?

Thanks again for all the great information on this site. I spend a lot of time reading about and learning from the experienced members on this site.
P.S. I first soloed in 1970 while in college with the ROTC FIP program. I sure love our 170 and have had many great flights. On Jan 1, this year, we finally worked our way to number 0 on the hanger list and moved into a T hanger at SFQ (Suffolk, VA). We had been in hangers for most of the 3 years we have owned the AC, but is is sure nice to have our "own place" for the plane. Total time on the hanger list: 3 years 4 months.
Gary N1909C (54' 170B)

I would talk to hartzell to see what your engine can swing. If your STC calls for a certain prop then I guess that's the one you have to work with unless that prop has been superceded with a new design. You would have to get the installation approved, Hartzell can probably provide some paperwork to help you with the approval. This is just my opinion, Hartzell has provided me with technical assistance in the past.

Hi Gary, when I talked to hartzel about this they said we could run their new 80'' propit has the dampner built in and will also do away with the RPM restrictions. they said that their STC would work on the AVCON conversion.

I bought a 80" prop from a Husky guy who was going to a MT prop. Hartzell sold me the STC for ............I think $500. I had a 76" on the airplane when I bought it...AVCON conversion.........There is a WAY big difference between the 76" and the 80". I'm on floats on a short lake and as Mike V. would say it "pulls like a tug boat."

Buck............Galena, AK