Dennis Schmaltz wrote: > Here's one for you. I have (supposedly) a C75-12. The prop on it, > according to the tag from the prop shop that was in the paperworks says > that the prop is a 1C90-LM7252. What engine is this prop supposed to be > on and what engine do I have? I say this becaused I cann't find > anything to indicate that my C75 was converted to a C85, but the dip > stick has been remarked to indicate 4.5 quarts and the plane has a tach > in it with markings for the 85 horse engine. Makes me wonder. > > I checked it earlier and it was still the C75 nameplate, but the > engine runs like a scawled banshee. In cruise flight, I can easily run > it out to 2550rpm at 5000 ft. msl. I keep it within the redline for a > C75 though. It will pull 2150rpm on the ground for a full power runup. > I believe the book says (I'm working from memory here) that the 75hp > should runup at 2100rpm. Anyway, it sure is a strong running little > engine.
Aircraft Specification A-718 which applies to the 415-C says
Propellers and Propeller Accessories
2. Propeller - fixed pitch metal, McCauley 1A90CF or 1B90CM
(a) With Continental C-75 series engines only
Static r.p.m. at maximum permissible throttle setting:
not over 2100, not under 1950. No additional tolerance
permitted.
Diameter: not over 73 in., not under 71 in.
To add confustion, Aircraft Specification A-787 which applies to all
models _after_ the 415-C says
Propeller and Propeller Accessories
2. McCauley 1A90 (Model 415-D with C-75 engine)
Static r.p.m. at maximum permissible throttle setting:
Not over 2110, not under 2010
No additional tolerance permitted
Diameter: not over 73 in., not under 71.5 in.
4. Fixed pitch metal, McCauley 1A90CF or 1B90CM
Eligible on Models M10, A-2, A2-A, 415-D (per NOTE 4(b)), E, G, F-1
and F-1A
Static r.p.m. at maximum permissible throttle settings:
For Models 415-D, E or G, not over 2225, not under 2025
For Models M10, A-2, A2-A, F-1, F-1A, not over 2375, not under
2250.
No additional tolerance permitted.
Diameter: not over 71 in., not under 69.5 in.
(note: I presume this applies to the C-85 and later engines though
it
doesn't say.)
I suspect you need to go by the text for the type certificate under
which your plane is currently certified: 415-C --> A-718, all later
--> A-787.
--
Ed Burkhead
East Peoria, Ill.
N3802H, 415-D
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