"gaits" for 172RG

wrote:

Does anyone have a crib sheet for the various "gaits" of the 172RG. By
gaits I mean the various MP/RPM/configuration settings (and their
associated airspeeds) that you use in different regimes of flight;
cruise, cruise climb/descent, holding, approach outside the OM, inside
the OM, etc.

o Climb: Cowl flaps open. Full throttle throughout climb, reduce RPM to 2500
at 1,000' AGL.

o Cruise: 25" MAP or full throttle, 2500 RPM, mixture lean of peak if
possible. Keep cowl flaps open in any but very cold weather; top of Cessna
CHT green is way too hot.

o Cruise descent: 18" or 20" MAP (depending on how smooth the air is), pitch
for 500 FPM. Cowl flaps closed.

o Holding: 18" MAP, gear & flaps up.

o Initial instr. approach segments: 20" MAP, 2500 RPM.

o Final instr. approach segment (slow): Mixture rich, 17" MAP (no wind), prop
in fine pitch, gear down, 1/3 flaps.

o Final instr. approach segment (fast) Mixture rich, 19" MAP (no wind),
prop in fine pitch, no gear or flaps until 1/4 mile final, then extend gear
(don't forget!) and 1/3 flaps simultaneously, then rest of flaps below IAS
white arc.

o Landing:
-Mixture rich, 17" MAP, prop in fine pitch, 1/3 flaps & gear down at
midfield downwind.
-15" MAP abeam touchdown.
-2/3 flaps, 80 KIAS on base leg.
-Full flaps, 70 KIAS on final.
-Throttle idle, 65 KIAS over the numbers.

--
Dan
C-172RG at BFM

Thanks, this helps! I'll try these out and then fine tune as
appropriate for my club's plane.

Interesting notes about temps and cowl flaps. As it turns out, I didn't
get to do my approaches yesterday in the Cutlass because it's in the
shop. Everyone has been noting how the oil temp has been at the very
high end of the green most of the time, and the pane pretty much needs
to be flown with the cowl flaps open, and they finally decided to do
something about it. Of course, I don't know what "something" is if this
airplane is just known to run hot.

So far they've changed the oil cooler and now have decided to change
the oil temp sensor, but no change.

The CHT, by the way, seems to stay quite comfortably in the green.

thanks,
dave j


Dan Luke wrote:
wrote:

Does anyone have a crib sheet for the various "gaits" of the 172RG. By
gaits I mean the various MP/RPM/configuration settings (and their
associated airspeeds) that you use in different regimes of flight;
cruise, cruise climb/descent, holding, approach outside the OM, inside
the OM, etc.

o Climb: Cowl flaps open. Full throttle throughout climb, reduce RPM to 2500
at 1,000' AGL.

o Cruise: 25" MAP or full throttle, 2500 RPM, mixture lean of peak if
possible. Keep cowl flaps open in any but very cold weather; top of Cessna
CHT green is way too hot.

o Cruise descent: 18" or 20" MAP (depending on how smooth the air is), pitch
for 500 FPM. Cowl flaps closed.

o Holding: 18" MAP, gear & flaps up.

o Initial instr. approach segments: 20" MAP, 2500 RPM.

o Final instr. approach segment (slow): Mixture rich, 17" MAP (no wind), prop
in fine pitch, gear down, 1/3 flaps.

o Final instr. approach segment (fast) Mixture rich, 19" MAP (no wind),
prop in fine pitch, no gear or flaps until 1/4 mile final, then extend gear
(don't forget!) and 1/3 flaps simultaneously, then rest of flaps below IAS
white arc.

o Landing:
-Mixture rich, 17" MAP, prop in fine pitch, 1/3 flaps & gear down at
midfield downwind.
-15" MAP abeam touchdown.
-2/3 flaps, 80 KIAS on base leg.
-Full flaps, 70 KIAS on final.
-Throttle idle, 65 KIAS over the numbers.

--
Dan
C-172RG at BFM

Interesting notes about temps and cowl flaps. As it turns out, I didn't
get to do my approaches yesterday in the Cutlass because it's in the
shop. Everyone has been noting how the oil temp has been at the very
high end of the green most of the time, and the pane pretty much needs
to be flown with the cowl flaps open, and they finally decided to do
something about it. Of course, I don't know what "something" is if this
airplane is just known to run hot.

I fly a cutlass in California with a similar problem. The top of the
green is 50 degrees cooler than actual redline temperature (it was sent
out for calibration). However, since the =only= marking on the gauge is
the green arc, knowing this doesn't help. So, I keep the cowl flaps
trailing open to stay in the green, which is the only way to know you're ok.

Jose
--
Quantum Mechanics is like this: God =does= play dice with the universe,
except there's no God, and there's no dice. And maybe there's no universe.
for Email, make the obvious change in the address.

wrote:

Interesting notes about temps and cowl flaps. As it turns out, I didn't
get to do my approaches yesterday in the Cutlass because it's in the
shop. Everyone has been noting how the oil temp has been at the very
high end of the green most of the time, and the pane pretty much needs
to be flown with the cowl flaps open, and they finally decided to do
something about it. Of course, I don't know what "something" is if this
airplane is just known to run hot.

So far they've changed the oil cooler and now have decided to change
the oil temp sensor, but no change.

They need to be concentrating on the baffles and baffle seals. Even a small
leak can make a big difference in cooling eficiency.

I've spent considerable effort making sure the baffle seals are perfect,
trying to get the CHT's to stay below 380 in cruise (I have a JPI engine
monitor) with the cowl flaps closed. That helped, but I still can't close
the cowl flaps all the way unless the OAT is well below standard.

The CHT, by the way, seems to stay quite comfortably in the green.

Yes, but the trouble is Cessna's idea of what's an ok CHT is considerably
higher than Lycoming's.

--
Dan
C-172RG at BFM

This is all very interesting, but slightly disturbing. Everyone's
flying around with their cowl flaps wide open? I guess that only costs
a couple of knots, but, it's just kind of disappointing that you can't
use them the way they're supposed to work. Well, I guess you can close
them you reduce power to descend but still keep the engine warm.

Anyhow, I have read that making sure the baffling is healthy is really
important, as the baffling was designed to direct airflow around the
engine in very specific ways, and "more open" is not necessarily
better.

I'll suggest they look at the baffles, but it's a club airplane and a
somewhat single-minded mechanic, so I may just be told to butt out.

-- dave j

Part 91 wrote:
wrote:

Interesting notes about temps and cowl flaps. As it turns out, I didn't
get to do my approaches yesterday in the Cutlass because it's in the
shop. Everyone has been noting how the oil temp has been at the very
high end of the green most of the time, and the pane pretty much needs
to be flown with the cowl flaps open, and they finally decided to do
something about it. Of course, I don't know what "something" is if this
airplane is just known to run hot.

So far they've changed the oil cooler and now have decided to change
the oil temp sensor, but no change.

They need to be concentrating on the baffles and baffle seals. Even a small
leak can make a big difference in cooling eficiency.

I've spent considerable effort making sure the baffle seals are perfect,
trying to get the CHT's to stay below 380 in cruise (I have a JPI engine
monitor) with the cowl flaps closed. That helped, but I still can't close
the cowl flaps all the way unless the OAT is well below standard.

The CHT, by the way, seems to stay quite comfortably in the green.

Yes, but the trouble is Cessna's idea of what's an ok CHT is considerably
higher than Lycoming's.

--
Dan
C-172RG at BFM