More propeller questions

[skyhopper]

Special thanks to Bruce, Miles, Pete and others on my first batch of questions about buying my first C170.

Have a couple other burning prop questions:

1. The plane in question has a McCauley DM7655 - what does the 55 stand for, does it speak to climb/cruise performance, and in what range of numbers does it belong?

2. The seaplane prop being offerred for sale in this forum is a McCauley "1A175/DM80 80-63". I have heard many folks speak of the '8040' and '8043' props - how does the prop for sale compare to these recommended sea props, and what is the specific difference between them?

3. The owner is asking $2200 for the DM80 80-63 prop with 12 hrs SNEW, including the STC - is this a good price?

One other overall question, the airplane I am looking at is on barnstormers - its a 1952 C170B N2674D IN ANNUAL for $38,500 - the engine has 250 SMOH in 1990 with channel chrome cylinders, and logs are complete only back to 1956, and P & I = 6/10 - amenities include lady legs, 1 piece windshield, Horton STOL, 875 useful load, clevelands, and no known damage history except wing replacement due to hail - should I dive in at this price and hope and pray the engine makes it another 1000 hours, or should I offer lower considering the engine scenario???

I look forward to contributing to this forum as I get more entanlged with my prospective airplane - thanks again guys

[N3243A]

Question 1: The later number is the propeller pitch. This is equivalent to the number of inches the prop should move during one revolution. A 55 inch pitch should move 55 inches over the ground in one rev and is considered very much a cruise prop pitch. A standard all around pitch on this prop is a 53 and a climb pitch would be 51.

Question 2: An 80-63? I think that 63 must be a typo, I have never heard of any pitch higher than about 46 on these 80 inch performance props.

Question 3: Is $2200 a good price? It isn't bad for only 12 since new. The STC is not included however, depsite what the seller may think. The STC for this prop follows the airframe serial number and will stay with his airframe. You will have to buy a new STC from Kenmore Air for installation of this prop on your airframe for $50 or $100. It was $100 6 years ago when I bought mine.

Regarding total engine time vs date of overhaul to determine the relaltive value of the airplane is a tough call and there are a lot of variables. 250 hours in 16 years isn't too bad. I bought my airplane with a 400 hour engine that was 25 years old and put another 1150 hours on it in the next 9 years with no big problems. How it was treated, hangered and flown will make the big difference as others have pointed out.

Bruce C.

[Bill Hart]

1. The 55 is the pitch of the prop or “Bite” It is how many inches forward in inches the prop would move in one rotation if used in a solid media. This is theoretical

2. 8063 doesn’t sound right to me. I am sure someone (George ) will correct me. If you are going to increase the leangth then you need to decrease pitch as the engine couldn’t swing the prop fast enough if you increase both.

Before you dive in to anything you NEED!!!!!!! to have an annual inspection done be someone who is quified to look at this type of airplane. There is nothing peculiar about the 170 that any A&P who works on 172’s can’t figure out but IMHO these are antique classics that should be worked on by people who are used to working on old airplanes.

[Jr.CubBuilder]

Ditto, don't buy the plane without an annual. You can have a "prepurchase inspection" done, but it doesn't mean anything. Get a full annual before you purchase it and you can spend a year learning to fly it before you take it apart again.

That plane sounds a lot like mine, the price seems a tad high, but that's what the seller is asking, feel free to offer less if you get serious. Take some time to make sure you will be happy with it as you see it. Fly it, look it over, open some of the inspection covers to see what the rust situation is. If you still want it, I suggest you agree on a price with the seller contigent on a decent annual by your mechanic not the sellers. The price of the annual will be on you, but if there are major problems that need to be fixed (like a new set of mag harness at $800 for example) you could renegotiate the selling price.

[GAHorn]

...8063 doesn’t sound right to me. I am sure someone (George ) will correct me. If you are going to increase the leangth then you need to ....

Be happy to oblige you, Bill... That word is spelled: L E N G T H .

[Bill Hart]

Damn spel check!