I'm getting pretty excited about my 170B conversion to 180 Hp and cs prop. Hopefully it's just a few weeks out now. For the record, it's a fuel-injected Lycoming IO-360 M1B, with roller tappets. Starting out it'll have a two-blade 210cm constant speed MT prop. That might get swapped for a 200cm three-blade MT down the road.

Not having much time with constant speed props, I've been trying to learn up on them. There are a few good threads here, but a lot of them morph into some pretty esoteric subject matter. Like the thread title says, I'm just looking for the basics I should know when I've got three knobs on the 170 panel staring back at me for the first time.

I'll be flying with experienced right-seaters initially, but want to prepare as much as I can in the meantime.

Thanks,

-DP

There is really no magic to a constant speed prop... Cycle the prop during run-up 4 times: 1 for MP, 2 for OP, 3 for RPM & 4 just because... The goal here is to make sure the system is sealed and the cold oil is cycled out of the prop.

In flight you will use it to get the most efficient climb on TO and RPM in cruise. That's pretty much it.

It's a good addition to your bird and I think you'll like flying behind it.

Jim

jaudette wrote:There is really no magic to a constant speed prop... Cycle the prop during run-up 4 times: 1 for MP, 2 for OP, 3 for RPM & 4 just because... The goal here is to make sure the system is sealed and the cold oil is cycled out of the prop.

In flight you will use it to get the most efficient climb on TO and RPM in cruise. That's pretty much it.

It's a good addition to your bird and I think you'll like flying behind it.

Jim

I agree that the CS prop is a great addition to your plane, and that they are pretty simple to use. I disagree with 4 cycles during run up though. Cycling the prop results in pretty high stresses in the engine and in the prop hub. I cycle twice, once for OP and once for MP. Only once after the engine has been running just to verify function. Another word of caution is to wait until the power and airspeed are low before setting to high rpm in the pattern prior to landing. I hear people shoving the lever forward with power and airspeed and jumping 200-300 rpms in an instant. It makes me cringe. This is pretty hard on an engine.

I'd cycle it once.. big strain on a warming crank.

Lets see, CS for Dummies.. like your car you have an engine and transmission.. you now have a throttle and a prop. Throttle is the gas peddle, prop is the tranny. Set MP with gas peddle. Done. Low gear on the tranny-prop (full-forward) for take-off, climb and landing. High gear (to set your desired rpm) for cruise. Done. From one Dummy to the next

Oh man... I hate it when everyone slaps me down...

I'm just going to have to stay on my own little island here and cycle my prop 4 times...

SixTwoLeemer wrote:I'd cycle it once.. big strain on a warming crank.

Agreed.

If it's cold out, like anywhere North cold, cycle it slowly a couple of times after the engine oil is at takeoff temp to get warm oil into the prop. Every where else I see no reason to cycle it more the once, and not deep - just enough to ensure it works. This assumes you pushed the prop all the way forward before you went to idle power, so it's flat pitch with the engine off.

Props with exposed counter weights (and no spinner) are usually shut down with the blades at max pitch, and should be cycled a couple of times to ensure they are flat for takeoff.

IMHO - YMMV

Take it for what its worth but I read an article in the one of the recent CPA mags from either Mike Busch or that other engine guru (can't remember his name now) that said cycling was hard on an engine and was essentially pointless. He also said that a typical mag check (1700 rpm) is useless. I can't remember his reasons now but it sounded legit.

I cycle once just enough to get a very slight rpm drop then off I go... Creature of habit I guess.

All you need to do with the prop in runup is verify that the governor will cycle the blades.

So, you're verifying that manifold pressure drops as you cycle it? Well, if it cycles, MP WILL change. Oil pressure drop during cycle? Ummm, if the thing cycles, it WILL drop oil pressure momentarily.

The point being, if the blades cycle, you can HEAR it. And if you hear it cycle, all those other things are happening as well.

Want to put warm oil in the hub? One cycle takes care of that as well.

Oh, and you don't need to cycle it so long that the prop rpm drops more than about 200 rpm max.

All that came from a Lycoming tech rep.

Otherwise, take off with all knobs full forward. Climb established, reduce power to your climb power setting.....check the engine manual that came with the engine. Typically, when you reduce power, you lower MP first with throttle. Then reduce prop rpm.

Increasing power, increase prop rpm first, then throttle.

And frankly, there's no totally universal reason to do that either, unless you're taking an FAA exam or check ride.

MTV

MTV

I have the same setup, basically just not fuel injected, the 83 in MT is like pushing a wall in fine pitch so I leave it at cruse setting until short final unless I'm trying to come in really steep. It is like having twice as much flap on landing and is really handy once you get used to it.

Other than that I use full fine for takeoff then pull her back to 2400rpm as soon as I've established climb, then once at altitude I pull the power back, usually to around 22in if I'm going somewhere, even lower if I'm just tooling around.lots of people think this is backward but it's how all the old bush pilots do it. I usually never touch the prop again until I'm on short final and have the power pulled almost all the way back.
Don't over complicate it!

Don't over complicate it!

Yup. It's a gearshift lever. In for low gear, out for high gear.

Make sure it works first flight of the day, easily when it's real cold (like where you live cold), and other than that, make it do what you want it to do.

Gump

From Continental's website:

b. Check throttle and propeller operation.
(1) Move propeller governor control toward low RPM pOSition and observe tachometer. Engine speed should decrease to minimum governing speed (200-300 RPM drop~. Return governor control to high speed position. Repeat this procedure two or three times to circulate warm oil into the propeller hub.
(2) Where applicable move propeller to "feather" position, Observe for 300 RPM drop below minimum governing RPM. then return control to "full increase" RPM position.

Found here: http://www.tcmlink.com/pdf2/maintenance ... x30041.pdf

Interesting to see the difference in procedure.

And for another procedure, the C-207 POH calls for pulling the prop control and leaving it out until the engine stabilizes at the lower RPM, 2x. Go figure.

Thanks guys. Gump- thanks for speaking slowly and using easy words.
How about some bad practices to avoid?
-DP

PA12_Pilot wrote:From Continental's website:

b. Check throttle and propeller operation.
(1) Move propeller governor control toward low RPM pOSition and observe tachometer. Engine speed should decrease to minimum governing speed (200-300 RPM drop~. Return governor control to high speed position. Repeat this procedure two or three times to circulate warm oil into the propeller hub.
(2) Where applicable move propeller to "feather" position, Observe for 300 RPM drop below minimum governing RPM. then return control to "full increase" RPM position.

Found here: http://www.tcmlink.com/pdf2/maintenance ... x30041.pdf

Interesting to see the difference in procedure.

And for another procedure, the C-207 POH calls for pulling the prop control and leaving it out until the engine stabilizes at the lower RPM, 2x. Go figure.

Eric,

Yeah, I read that as well some time back. Some of us were having a discussion on the subject one weathered day at the aerodrome....so I started making some calls. I called a Lycoming rep, who gave the response I noted above. Then I called a TCM rep, and he said pretty much the same thing. I referred to the Cessna POH's etc, and he said, essentially, "Yep, that works too". I asked both these guys what cycling the prop three times (which seems to be the standard in most places) does that cycling the prop once doesn't. Both answered "nothing, but we've always cycled them three times"......

Sometimes aviation is like that.

MTV

When I got my 170, I was in your boat. Not really sure what to do just wanted to make sure I didnt screw something up. Started out cycling 3 times. Did that for about a year. Then decided to start doing it twice, just becouse I was sort of lazy and didn't see the need for the 3rd. Now, only once, kind of slow, but really depends on how warm the engine is at the point I do it.
I also started out at 24 squared. Then flew for a long time with 23 as my number. I have the wonderfully worthless Hartzell with a great waste of time prop rpm limitation, so I am limited on my combinations to play with. If I didn't have that I would probably roll back to say 2200rpm and try to stay at 23 or 24". I know the old rule of thumb was keep the prop on top, and I do, to a point. When making power changes I always go prop first.
Man that MT should be awesome with that engine!
Greg

GumpAir wrote:

Don't over complicate it!

Yup. It's a gearshift lever. In for low gear, out for high gear.

Make sure it works first flight of the day, easily when it's real cold (like where you live cold), and other than that, make it do what you want it to do.

Gump

the more you think of it like a car the better you'll treat it...

Don't burn up the whole pattern in low gear, it just burns gas, makes noise and ticks off the neighbors...

Don't scream into the pattern and then use the gear shift to slow you down, aerodynamic braking further out is free, doesn't add wear and tear on your engine or piss off the neighbors...

Don't loaf around in sketchy country while in overdrive... When things get really hairy and you shove the GO button forward you are likely to forget the shifter... Cruise at over squared settings is just dandy, but laying the whip to it while you are loafing around at 2000 RPM is going to cost you MX dollars... This doesn't necessarily mean you need to be in granny low, after all you have an infinitely adjustable tranny.

Since you invested in one pay attention to your engine monitor while you play with different power settings... That alone will debunk many old wives tales and teach you more about what makes / keeps your engine happy than anything else.

Take care, Rob

Again, make sure you get a copy of the little maroon covered booklet that Lycoming distributes with their engines. It's pretty generic, but it does give you some notions on what percent power that various power settings equate to. And, as noted in other threads, for example, Lycoming recommends against any leaning at greater than 75 % power. Where you're at, it'll actually make well over 75 % power many days, even in cruise flight.

As Rob notes, "oversquare" operations work great on these engines, particularly with the MT prop....smooth and quiet and fuel efficient. I've run a Husky with that engine and prop....amazing. A Lycoming rep, in response to my question about oversquare ops replied "anything up to 9 inches oversquare works fine on these engines." And, you'll never get that far oversquare...

In any case, none of this is rocket science.

MTV

DP

All good advice above. Great to see you are getting the 180 conversion with the CS prop. I had this setup on my 170B along with a STOL kit and all make the 170 a real performer and fun airplane. The MT prop will be a big plus as well.

Nizina

Nizina wrote:DP

All good advice above. Great to see you are getting the 180 conversion with the CS prop. I had this setup on my 170B along with a STOL kit and all make the 170 a real performer and fun airplane. The MT prop will be a big plus as well.

Nizina

Thanks Nizina. I also got a Sportsman this winter while I was waiting for the new engine, so it should have some new zip in it for sure.
-DP

Are there no issues with harmonics with the MT prop? If not then I find the most important thing to keep in mind is to be sure you flatten the prop well before you might need power. I don't have a governor on my setup so adjustment is manual but there is a definite lag in time when going from course (cruise) to climb (fine). It isn't an awful lot but if you are low and slow and need power quick it can seem like forever waiting for the prop to cycle and the engine to spool up all while that damn big cottonwood tree gets bigger and bigger and bigger. In normal flight just use it gently so you don't shock load the engine and have fun.

I posted this a few years ago on the skywagon forum. It has a manual from McCauley in it that you might find interesting. Hopefully the link works.

http://www.skywagons.org/forum/showflat ... e#Post1426

Wayne