The International Cessna^® 170 Association

Hi
I am looking at putting a 1A175SFC 8040 prop on my 170B, for Ski season, I have a O-300D engine.
I recall reading some-ones post about the required criteria,... ?
Something along the lines of X number of inches required from the prop tip with one main
wheel tire deflated ?

Also does anyone have any approvals for this prop on a 170B with the O-300D. ( Kemore's STC
is for the O-300A+B, only )(which is the "DM" Hub )
I have contacted Wick's in Alaska , they are "lending me" their paperwork so I may attempt to
get their STC to include the "SFC 6 Bolt Hub".
If any one has an approval or knows of an applicable STC please contact me.


Thanks John

I've got the 8043 on my 0-300D, had it on there for 26 years without problems. There is a distance that is required between the prop and ground with one flat tire, someone may chime in, can't remember what it is though. I think the association has an STC on file for the combo, if not I may be able to help you. I'm out of time right now but I'll be back around tomorrow night.

Joe
360-430-0634

Thanks Joe,
I would be interested in hearing about what performance you get ? ?
Are you on wheels only ? What size tires do you run ?

I would really appreciate any paperwork you could share with me ?

Thanks John

Hey John,

Wheels only, 800-6 tires. The prop was on my 170B when I bought it 26 years ago and I haven't flown one with a cruise prop so I don't have any first hand experience of the difference. I have flown along side other 170's though and I definitely out climb them! I cruise about 105-108 mph at 2450. At best rate (89 mph) it turns close to 2700 rpm so I'm getting the max hp out of a 0300 in climb anyway. I have a 650' strip at my house and don't have any problems flying in-and-out solo, it would do it with two people I'm sure, but just don't press my luck.

I just looked at my STC and it is a "one-time" STC for my plane only. The Association may have one on file for that configuration, you'll have to check with headquarters. If not, I could scan my STC and send you a copy if it would help you somehow.

joe

Don't recall anything about a flat tire but CAR3 (Small Airplanes Certification Basis -1949) required a 7-9" prop to ground clearance in the level attitude (as in a wheel landing.)

14 CFR 23.925 wrote:(a) Ground clearance. There must be a clearance of at least seven inches (for each airplane with nose wheel landing gear) or nine inches (for each airplane with tail wheel landing gear) between each propeller and the ground with the landing gear statically deflected and in the level, normal takeoff, or taxing attitude, whichever is most critical. In addition, for each airplane with conventional landing gear struts using fluid or mechanical means for absorbing landing shocks, there must be positive clearance between the propeller and the ground in the level takeoff attitude with the critical tire completely deflated and the corresponding landing gear strut bottomed. Positive clearance for airplanes using leaf spring struts is shown with a deflection corresponding to 1.5g.

CAR3 pretty much says the same thing.
http://www.navioneer.org/riprelay/Yet%2 ... _part3.pdf

Hi David,

Yes, Thanks , that is what I was looking for.

But that brings into question, how much is ,.. " positive clearance between the propeller and the ground in the level takeoff attitude with the critical tire completely deflated " does that mean the 9 inches ? or just, some clearance ?? with the tire deflated ?


John

positive clearance to me means not a negative clearance. if it aint touching the ground, there is a clearance that can be measured in positive numbers.
If they wanted a specific amount of clearance, they would have given a specific amount like they did with the 9 inches at 1g deflection in level flight.

in my opinion, of course.

I don't see anything about a deflated tire. It's 9" for a tailwheel in level attitude with the spring gear positioned as for a 1.5G landing (however THAT is accomplished!)

gahorn wrote:I don't see anything about a deflated tire. It's 9" for a tailwheel in level attitude with the spring gear positioned as for a 1.5G landing (however THAT is accomplished!)

Level the airplane, then load it until it weighs 3300lb...

In addition to subparagraph (1) of this
paragraph, there shall be positive clearance
between the propeller and the ground when, with
the airplane in the level take-off attitude, the
critical tire is completely deflated and the
corresponding landing gear strut is completely
bottomed.

cessna170bdriver wrote:

gahorn wrote:I don't see anything about a deflated tire. It's 9" for a tailwheel in level attitude with the spring gear positioned as for a 1.5G landing (however THAT is accomplished!)

Level the airplane, then load it until it weighs 3300lb...

Yes, but HOW do you load it? What is the maximum floor loading per square foot? What to use for ballast? Where to place the ballast to avoid structural distress?

George,
I intended my answer to be smart(alek), thus the emoticon and NOT the everyone-should-know-that emoticon.

But as long as you're asking, put 500lb of shot bags in each seat of a 1300lb airplane. That's less than the load exerted by an FAA standard human in a normal category maneuver.

Yeah, I knew your intent...but I was serious about my question. One of the reasons seat tracks have the mx issues they do is because we Americans are no longer 150-170 lbs. I remember reading the floor-stress limit on our airplanes...I just don't know where I read it (so don't rely on these figures).... but I seem to recall 120 lbs/sq.ft. and the seats themselves were only stressed for 220 lbs each. (I exceed that.)

gahorn wrote:...the seats themselves were only stressed for 220 lbs each. (I exceed that.)

Yeah George, you and I probably need to stick to normal category operations...