Before MTV takes my head off or Chis tells the pigs to eat me. This response is from one of the instructors. FWIW he is right about the MFG.'S.
As for myself I would like to understand more about the mechanism that engages the prop via the engine? I assume it is round with teeth?

"Bill I don't know exactly how to respond to this kind of stuff.
Everybody has what they think are the right ways to do things and we
who teach and fly thousands of hours in the backcountry have our
opinions and methods too. In this case the prop talk is based on
pilots and mechanics who use, service and replace governors and props.
All I can say is everyone, including you, have the right to learn as
much as you can about the parts and how they are used and then decide
for yourself how they should be operated. I will tell you that this
response is understandable from manufacturers who are worried about
being sued, and yes explaining a procedure and policy that will work
for as many people as possible."

hope this keeps the hot water from scalding you.
artie

Sojorrn,

Sorry if I came across as wanting to take your head off. I think he's way off base on this, for several reasons, and I'd hate to see anyone get hurt or bend an airplane because of bad information.

The manufacturers aren't just spouting liability issues here--they are simply promoting good practices. And, I agree with them. For background, I operated for nearly 30 years and well over 11,000 hours flight time, mostly in the off airport environment. I've worked closely with mechanics over the years, learning everything I could about procedures and practices and maintenance issues with airplanes. This is the first and only time I've ever heard something like this even suggested.

I cycle props prior to the first launch each day, because I believe it is good operating practice, not just because the manufacturer says to do so, but the combination makes this a no brainer. Done properly, particularly in a tailwheel airplane,(which generally have lots of prop clearance) there is very little if any risk of inflicting prop blade damage during the runup from FOD.

You stated in your earlier post that the instructors claimed that cycling the prop could somehow damage the prop internal mechanism. Ask yourself this: If that were the case, and as your instructor suggests in his response, Hartzell is totally focused on liability, wouldn't it be pretty stupid of Hartzell to recommend a procedure that could damage the prop??? Who do you suppose the unfortunate pilot is going to sue if that prop comes apart on takeoff?? My bet would be Hartzell.

So, I agree that Hartzell is in fact liability (and by association--safety) oriented, and they recommend a procedure that if done properly prior to flight, could alert you to an unsafe condition in your propeller BEFORE you are airborne in a nasty canyon, with no place safe to land straight ahead and no way to circle to land.

That is precisely the point when it comes to back country and off airport flying--any kind of mechanical failure right after takeoff is generally gonna be ugly. Of course, that is also often the case around airports as well.

I really don't know what else to say. In my opinion, these guys are passing out bad information in this instance. That doesn't mean anything else they say is incorrect, though. I have heard good things about their program.

But, I'd cycle that prop--carefully--prior to the first launch every day. It's worked for me for a lot of years, and a lot of launches. But, whatever winds your watch.

MTV

Gotta say that I'm with MTV and the others.

I have NEVER had a factory rep or mechanic tell me not to cycle a prop first flight of the day, and in 38 years and 15K+ hours all in the boonies, I've flown a shitload of airplanes from new in the crate engine and prop clear out to TBO in some damn harsh conditions. And, I have NEVER had a prop governor, hub or blade fail on me.

First flight of the day. That's the only run up I do during a flying day, and that's the only time I cycle the pitch on the ground. I want to know it's working before I get in the air, and, especially if it's cold out, I want thinner, warmer oil circulating thru the thing.

Guys with lots of military, airline, and air race time might be very, very good at what they do, but.... I take what I hear with a huge grain of salt, when it comes from people who don't live/fly in my world.

Gump

Sojorrn,
I just bumped into this thread. The prop governor is driven off of the front of the engine by means of a gear and a shaft. It is I think exactly like the old steam engine governor in that it's primary control is a set of fly weights that control RPM, but I've not been inside of a steam engine governor, so I'm unsure. There used to be and may still be for all I know variable pitch props. What I'm sure we all have is constant speed props, we control the PRM, the governor controls the pitch to maintain RPM. The variable pitch props would change RPM with pitch attitude unlike our constant speed props.
There is no connection between the governor and the prop. The governor is nothing more than a valve that sends oil pressure to the prop dome. Oil pressure in most recip props drives the prop to high pitch/low RPM. Releasing oil pressure drives the prop to low pitch/high RPM. A spring is used in our props, but there used to be many counterweighted props where the counterweight was the driving force to reduce pitch. All governor failures that I have seen result in the high RPM setting. If the prop stops were set where they are supposed to be, you can prevent the engine from over-revving, but your not producing a whole lot of climb power either. If your really in a position where full power is just barely enough, then you may be in a world of hurt.
The prop dome is a dead end, there is no oil flow through there. Not a good design in my poinion, but they didn't ask me. Any way I've seen many engines that essentially were full of sludge in the crankshaft and the prop. Oil the consistenancy of Jello. It seems that there is a correlation of this sludge with people that won't fully cycle their prop or won't do it the recommended three times. My theory is that by cycling it fully three times, you flush some of the oil out of the crank and prop. I seriously doubt that you could induce detonation by pulling a prop all of the way back on a non turbocharged engine at say 2,000 RPM. If your oil pressure drops out of the green, then you have a problem that needs to be fixed. Excessively worn oil pump for example.
Personally, unless there is a real compelling reason not to, all of my run-ups are the same. Being retired military, standardization was beat into my head for 20 years and I have become a fan of it, so all of my run-ups I cycle the prop three times as recommended. No I won't sit in a dust bowl blowing and injesting dust into my engine, but if conditions allow I do a full run-up every time.
On edit, this is what I do in my Maule flying my family around when almost every landing results in an engine shut down and quite a bit of down time. If your in a work plane making many landings and take offs without engine shutdowns then I forego run-ups entirely.

Some good advice here...

.......concerning cycling the prop over rocks etc.

But......come on guys...The airlines general aviation and military have billions of ancient flight hours in proprellor driven airplanes. Billions.

Try telling a Lockheed "Connie" Flight engineer or a Merlin powered P-51 pilot(not a radial engine....) that they shouldn't cycle the prop! For that matter question an old DC-3 or Twin Beech pilot!

Hell guys. It is just like every thing else on the checklist. There is a reason for doing it. Otherwise let's just dump the whole preflight.

The guys at McCall are great. But if they suggest one should never cycle the prop...then they are just flat out wrong. Or at least everything they taught until last year was wrong.

What makes them think that they got it figured out 80 years and billions of flight hours after constant speed props came into existence?

I've logged over 30,000 hours; mostly airline but 6,000 in general aviation. Radial engines to turbine. I have had a counterweight come off a prop, prop overspeeds, turbine meltdowns, fan blades disinegrate and cylinder heads blow off. I'll follow the manufacturers recommendations any time. It has worked since Wilbur and Orville.

Bob cycles first flight, unless it is over a loose surface...)

MTV,
I was only kidding you and Chris. I know passion when I hear it !
A64 added this to the Maule site:
"I've had a couple of explanations as to why not cycle a prop, from excessively lugging an engine to "it will drop the engine oil pressure too much". I don't think most people really understand how some of the systems work. Flight instructors are the worst for spreading rumors. They mean well and have a captive audience, and people listen to them on things they really don't know what they are talking about. The military instructor pilots are the worst.
On most single engine recip aircraft the prop is driven to flat pitch by a spring in the hub of the prop. Engine oil pressure is used to overcome thisspring pressure to increase prop pitch. You do not directly control prop pitch, you control prop RPM with the prop governor. The prop governor will send oil pressure to the prop or remove it to control RPM. That's why nothing will happen if you try to cycle the prop at a low RPM. If the engine looses oil pressure, the prop will be forced by spring pressure to the high RPM stop. That is why pulling the prop lever out in the event of an engine failure won't help anything, as the engine slows to a stop, the oil pressure will be lost and the prop will return to flat pitch and as the engine slows, the governor will flatten the pitch to try to maintain the RPM that corresponds to the min. setting of the governor. Most instructors are sold on this helping because it will in fact help if you just simulate an engine failure, but not if it really quits. Your best glide ratio will be with the prop stopped, not windmilling.
Now if it is real cold, then cycling the prop may be bad on the cold seals, I don't know, but if it is real cold, how are you going to get that congealed oil out of the prop so that it will function properly without cycling it? My 2 cents is to exercise everything the airplane has frequently. Things on an airplane seem to work better if frequently used.
I guess where this is going is do what the manufacturers tell you to do in the run-up, if that doesn't work you can call them and ask why."

I respect all the inputs from Floyd, MTV,Chris AKA Jr. Cub, Jody, & Chris & his Pig!
I really fall on the side of exercise everything in the aircraft logic. I also agree with MTV point and lower the RPM to 1300to 1500 but do it the first to flight of the day. I also like what Jr Cub Builder said:
"I need a more definitive and plausible explanation than something to the effect of; because we know better and we have a mechanic that agrees with us so forget what the OEM people say."

Also Floyd made a good observation :
"Bill one of the great things about flying is you meet so many people and hear so many opinions.
The key is weeding out the chaff, as presented they have no basis for the argument."

I especially liked GT's conclusion:
"Usually the fault is with the right hand of the PROP NUT! "

I thank you all for your inputs and passion.

I love to fly except for heavy turbulence, Smoke ,& haze. But they haven't stopped me from starting up the engine and they never will!
Fly Safe

Sojorrn,

One of my long term aviation mentors and great friends told me many times that aviation safety is all about learning, and if you don't learn SOMETHING every time you fly, you obviously weren't paying attention.

I tell all my students this little piece of advice:

Listen to everyone's opinions on aviation operations and safety. If someone presents a suggestion or advice or technique to you, think about it carefully. Ask the presenter the all important question "Why?". See if their explanation makes sense to you, and follows logic. If the person can't explain the "why" or if their response is simply "Because I've determined this is the best way to do it, trust me", you may want to discard the suggestion right there.

Otherwise, turn it over in your mind, present it to a few others, then give it a try, under controlled circumstances--with an instructor or experienced aviator, give it a fair trial. If it works for you, it is now YOUR technique--put it in your tool box.

If it doesn't make sense to you, the presenter can't explain the "Why" of it, or it just doesn't work for you, then discard it and move on.

And, all of that applies specifically to most everything I tell you as well, by the way.

None of us has all the answers.

MTV

FWIW, at the recommenced 1800 RPM the IO-520 in our C-210L won't do anything, that is too low of an RPM, but at 2000 it cycles fine. I wouldn't think that 1300 to 1500 is enough, but try it your self. You have to be inside of the operating range of the governor of course for anything to happen.
I made that post on the Maule site before I read this one.
If you ever change the governor, make sure the gasket you use has a fine screen wire in it, the screen wire will prevent at least some metal from contaminating the engine if the governor eats itself. The overhaul gasket set that I bought for my 540 didn't have the screen in it, I had to buy another one that did.

well I learned something here. I thought you had to cycle before each flight. Now I know it only has to be done before the first flight of the day....I do my checklist on each flight and it doesn't say only the first flight. It says cycle prop so I have been doing that. I have the Cont. IO 360 with a McCauley but I gather the op proceedure is the same as Lyc. Good to learn a few things here..... Sorry I missed you Sojourn. Saw your plane on the ramp a couple times when I went shopping and fuel stops....Pretty.....

Here is a response to my query about your inputs!
"It's not so much damage to the blades we are concerned with as the
torsional (spelling) effects from loading and unloading the crankshaft
and the rods and bearings. We are convinced that this kind of
treatment, especially on a cold ground running engine is causing
cracks in crankshafts. Also, I will send you a site that shows a slow
motion picture of the blades of your prop as it is being cycled. The
tips of the blades move close to three inches fore and aft near the
tips. It's spooky. As I said before, we believe it is your right and
responsibility to review all these procedures that are "accepted
practice" and determine for yourself whether they are appropriate. As
you your web site friends, these forums are famous for pot shots out
of context. None of them took the time to sit in the class for 25
hours and listen to everything we weave together to make safer risk
management decisions regarding backcountry operations."

Jody, MTV, Floyd, Chris, Hammer, I would be interested in your feedback.
I took off this morning for O22 ( Coumbia - Yosemite_ Sonora) I cycled the prop 3 times @ 2000RPM per the POH. BTW beautiful flight, Calm and Clear. with a very nice controlled landing. So I learned something that makes it all worth while.

Hi Butch, I will catch up to you soon as I can! A few more private lessons. and I'll be in the thick of it! my regret is that I did not go into JC but there are other flyins- Like this month.

Sojorrn wrote:None of them took the time to sit in the class for 25
hours and listen to everything we weave together to make safer risk
management decisions regarding backcountry operations."

And he wasn't sitting with us for all the years and tens of thousands of hours of professional, accident free backcountry flying either. Whole lot of classes to sit through in this world, some are worth every second, others nothing but smoke and mirrors.

Hartzell, McCauley or Continental tell me to stop cycling my prop on a non-turbine engine, and explain why, then I'll sit up and pay attention. Some self-proclaimed guru, out to sound knowlegable in front of a class full of students, I'll treat that like bullshit until proven otherwise.

Gump

Jr.CubBuilder wrote:

Sojorrn wrote:Here is a response to my query about your inputs!
"It's not so much damage to the blades we are concerned with as the
torsional (spelling) effects from loading and unloading the crankshaft
and the rods and bearings. We are convinced that this kind of
treatment, especially on a cold ground running engine is causing
cracks in crankshafts.

Hmmmmmmm..........I'm not buying it. It's an interesting theory but I don't think the temperature spread is enough to support the cracking because it's cold idea. If you froze the crank to -200C and then fired the motor up that would probably make a difference, but even well below freezing steel maintains it's strength.

As
you your web site friends, these forums are famous for pot shots out
of context. None of them took the time to sit in the class for 25
hours and listen to everything we weave together to make safer risk
management decisions regarding backcountry operations."

Jody, MTV, Floyd, Chris, Hammer, I would be interested in your feedback.
I took off this morning for O22 ( Coumbia - Yosemite_ Sonora) I cycled the prop 3 times @ 2000RPM per the POH. BTW beautiful flight, Calm and Clear. with a very nice controlled landing. So I learned something that makes it all worth while.

Hi Butch, I will catch up to you soon as I can! A few more private lessons. and I'll be in the thick of it! my regret is that I did not go into JC but there are other flyins- Like this month.

I don't mean to be taking pot shots at the fellow and I'm sure he's got lots of knowledge that I don't about flying. However I don't think they've made a very good argument for their point that cycling your prop hurts the motor. They have not presented any quantifiable data to that point, only conjecture that flies in the face documented proper procedure. Had I been sitting through their class I would have definitely discarded the idea that cycling my prop would damage the internals of my motor or prop hub.

Excellent point regarding the data and testing to prove the position. As for the pot shot remark. I always get suspicious when someone gets defensive and attacks personally instead of sticking to the subject!

GumpAir wrote:

Sojorrn wrote:None of them took the time to sit in the class for 25
hours and listen to everything we weave together to make safer risk
management decisions regarding backcountry operations."

And he wasn't sitting with us for all the years and tens of thousands of hours of professional, accident free backcountry flying either. Whole lot of classes to sit through in this world, some are worth every second, others nothing but smoke and mirrors.

Hartzell, McCauley or Continental tell me to stop cycling my prop on a non-turbine engine, and explain why, then I'll sit up and pay attention. Some self-proclaimed guru, out to sound knowledgeable in front of a class full of students, I'll treat that like bullshit until proven otherwise.

Gump

Gump,
I love it when you sugar coat your point of view Although your point is spot on! Where is the empirical method and the data to prove the hypothesis? Beginning to sound like Global Warming.
I know! I'll ask him, How do you like my friends so far? The more I think about it one would think they would have presented a paper to the FAA with charts, graphs, and photo's.

Well, DANG!!! NOW I know why that crankshaft broke at the #2 rod journal on me in 96!! Always wondered about that.

Sorry, but in case this fellow hasn't been paying attention, there have been a few crankshaft failures over the years, precisely NONE of which have been tied to prop cycling during runup by anyone. Yet, the engine, airframe and prop manufacturers still insist you should cycle the prop prior to first takeoff of the day. Hmmm. And, I always thought they'd know a little bit about the equipment they build..

I ran this by my current mechanic today, just for fun. I explained the argument with a straight face, and as presented here... He just started laughing. His response: You cycle the prop to get the air out of it and the lines, so that you don't KILL yourself during or right after takeoff. Yup.

a64: Every engine/prop model combination cycles at a little different rpm. My O-360 will cycle just fine at 1500 or a little less. I've seen IO 520's that wouldn't cycle till you got to 1700, but if one wouldn't cycle at a little over 1700, I'd get someone to check it out. If I recall, the IO 520 calls for runups at 1750. If it wont' cycle there, it's not right.

sojorrn: I know Maule says to do runups at 2000 rpm. Note that other manufacturers who use precisely the same engine/prop combination (Aviat for one) recommend 1700 or 1800 for runup. Piper has a big thing about doing runups in their low wing airplanes at 2000, and it makes me crazy. I would do run-ups in those airplanes and in a Maule at around 1700 to 1800 rpm. That range is approved by the engine manufacturer and the prop manufacturer, and it is less likely to pick up rocks, etc, and damage prop blades. I'm a believer in following process, but you can verify everything you need to verify at 1700 just as easy as at 2000, and do a lot less damage to the prop blades.

But, as I noted earlier, whatever winds your watch I reckon.....

And, I too wish that Gump would be a little more direct in his responses....sometimes it's hard to decipher his subtle innuendos...

MTV

mtv wrote:And, I too wish that Gump would be a little more direct in his responses....sometimes it's hard to decipher his subtle innuendos...

MTV

I do whatever the little voices in my head tell me to do. They get loud sometimes.

Gump

Ya know there is a whole lot of testing that goes on, harmonics and all.

The two-stroke guys for years have talked about long props loading the crankshaft, and scoring the main brgs. The VW guys have been breaking cranks with props for years.

The V-8 guys have broken a few when they run without a harmonic balancer.

I could give you tons of data about cranks and steel but it would be meaningless to you.

Mag type and timing have way more detrimental effect on 3rd order and up harmonics with a prop and crank combo.

Many prop companies freaked when electronic ignition started hitting the market and many still do.

Read a bunch of NASA reports you will see tons of data that doesnt include problems from prop cycles. You will however find that the type of ignition system can totally change the resonance leading to a failure.

As far as the rpm goes I do it about 1600 rpm

And sometimes I pull it out and leave it while I taxi just to put the engine under a bit of load. Helps keep your plugs clean

Want to make sure you never have a prop related broken crank go with a MT prop.

Can we put this horse back in the barn before it drops dead?

Ok! Since Floyd has made a request sit back and listen to another pet peeve the school rants to students about.
The Vernier vs Friction throttle. They actually pestered me and one other poor soul to duct tape the button in so they could have some control over the throttle. No Screwing was the mantra. I held out until the last day and then got questioned because with the button in the friction is kaput. So if you reach down to trim, your throttle slides out and you drop from 15 to 10 inches of MP
It took me all of 5 seconds to figure out what was going on so the instructor said just keep your hand on the throttle. I replied only if you TRIM!

Think I'm just gonna shut up here, and go get myself another glass of wine.

Gump

My opinion, You do what the manufacturer of the airplane recommends unless you've installed some sort of STC that modifies procedures. If this is the case then the STC should tell you what procedure to follow.
If you want to do your own thing then that's perfectly acceptable. Matter of fact there is a whole catagory of aircraft (experimental) and a fine organization just for you (EAA).
If you think a prop flexes during run-up then you should see what a helicopter blade does in flight. I don't know what either has to do with anything though.
My contribution to the "Aviation Legends" is this, There are two things you can do that will play hell with your crank and prop. 1. Aerobatic flight 2. whipping it around quick at the end of the runway or parking spot. You see the prop is of course a gyroscope and rapid changes of pitch or heading at high RPM cause excessive forces that result in bending forces in the prop hub and crank.
Old Ag pilots will caution you from whipping it around at the loading truck or ramp. I have no proof, but it makes sense to me and costs nothing to always make slow turns, probably safer that way anyway, and it's not in conflict with any written procedure that I know of.
As far as cold cranks go, I won't turn up the engine to 2000 RPM if it's cold regardless if it has a constant speed or fixed prop. I don't have any experience operating piston engines in artic conditions, but I thought if it was real cold that it was especially important to cycle the prop to get warm oil into the prop dome?
I'll look into why my IO-520 won't cycle until 2000 RPM, but as it was a Continental overhaul with all accessories, I thought it was the way it was supposed to be. The only thing I think it could be is that the governor is set wrong for this engine/prop combo in that airframe. Governors are set differently of course depending on the airframe, prop and engine.
He is correct in telling you that there is no end to advice on the internet and my advice is that any time you get advice that conflicts with written procedure, at least call the manufacturer and ask why they recommend something. Remember they have to try to come up with procedures that will work in artic cold, desert heat, high and low DA and everything between. The guy's at Lycoming's help desk and at Hartzell have been very helpful to me.
Some people make a living modifying they way their products are used, GAMI for example, and when warranty time comes, will GAMI for example buy you a new cylinder? It's tough for the OEM guy's to battle things like that.
Hartzell's GAMI is LAZAR.
Sorry to get off topic, but there is a long line of people that will tell you that Lycoming and Hartzell or Mac, don't know how their products should be operated and I think that's a problem.