WingFlaps wrote in news:cb62baf1-cf48-423f-b9c5-
:

On Apr 18, 2:43Â*pm, Bertie the Bunyip wrote:
WingFlaps wrote in news:d33d5865-938c-4cae-
acb3-
:



On Apr 18, 9:20�am, Andrew Sarangan wrote:


Even if the airplane is perfectly airworthy, and all maintenance
done
properly, you don't know if the engine is producing 160HP (or
whatever
the rated power for your airplane). There is no signature in the
logbook that certifies that the airplane engine has been tested
and
found to produce the specified power. I have flown rentals that
flew
like a 120HP Cessna instead of a 160 HP. RPM can't tell you the
true
power because every airplane uses a different pitch prop.

Well if the renter is slappin' on any old prop then you should not
go
there. How does a 120 HP 172 reach cruise airspeed at cruise RPM?

Coasely pitched props don't allow good static HP because the RPM
doesn't
get up to where it needs to be to produce HP. That's what variable
pitch
props are all about.


Yes, but my point is that cruise speed also tells you about HP on a
daily basis. As far as I know, there are only a very limited number of
approved props for each 172 variant. If you don't see the magic static
RPM as specified in the POH it's time to investigate not fly -right?

Oh, OK, yeah, that's right. But you can have an absolutely beat engine
and still get the revs in cruise for most airplanes. My father had an
old Mercedes I borrowed off him once. Went fine, but he lived in a very
flat area and I took it to a multi story parking lot and couldn't get it
up the ramp. I looked around it the next day and found the cam lobes
almost round!




Bertie