FX3 options/recommendations for off-airport ops

[soyAnarchisto]

Perhaps the Continental O470's have a different governor or a different behavior than the CC363i, which is what lycoming based? And what prop are we talking? the 80" trailblazer - two blade right?

I dunno. But if you would like a ride in a 180 with an 88" seaplane prop, you can see it demonstrated rather dramatically. Pull the prop back with the engine at idle and the drag reduction and extension to glide is tremendous. And of course, there's no mention of doing this in the engine out emergency procedure. Of course this is 1955 so the emergency check-list is pretty much non-existent.

I figured this out real quick in practicing my commercial maneuvers prepping for a check ride. A power off 180 with pulling/feathering the prop back is pretty normal landing. But if you leave the prop full fine, you will drop out of the sky like a brick... a mushing brick but a brick nonetheless. I assumed all airplanes were configured to go full fine when you lose oil pressure - but that sure is not good for best glide.

What's supposed to happen when you are "below governing speed" on the rpms? Does it go full fine, or full coarse? Or does it somehow magically stay in whatver position it was in when you pulled the manifold pressure back to idle?

If my governor is not working correctly, I'd sure like to know it. It is in annual and I flew it with my IA aboard noting this behavior during my annual. Seemed totally normal behavior to me. I admit I didn't get to do the exact same experiment in the FX3 I flew last summer.

 

[frequent_flyer]

Perhaps the Continental O470's have a different governor or a different behavior than the CC363i, which is what lycoming based? And what prop are we talking? the 80" trailblazer - two plade right?

80 inch Harzell Trailblazer (2 blade) on a Lycoming IO-360 (CC specified mods make it a CC363i). Governor appears to be Hartzell S-1-73 but I have not verified that.

Prop is fine pitch with engine stopped. Propeller control is normal throughout the governing range and I have no reason to believe the prop and governor are not behaving exactly as the manufacturer intended. I assume that anytime the engine is at lower RPM than expected for the governor setting that the prop is at full fine pitch.

I'd jump at the chance of some seaplane time. I only have the 5 hours it took to get the trophy rating in a PA-18-150.

 

[skywagon8a]

What's supposed to happen when you are "below governing speed" on the rpms? Does it go full fine, or full coarse? Or does it somehow magically stay in whatever position it was in when you pulled the manifold pressure back to idle?

You need to understand how the governor works. There is a pair of spinning fly weights that apply a lifting force (depending on rpm) to the pilot valve which in turn controls how much oil is directed to or from the propeller. On top of the flyweights is a spring providing an opposing force. The prop control in the cockpit varies the spring pressure. So, in normal operation during landings the prop control is set to pull the spring towards the fine pitch direction. When the throttle is pulled back enough (low mp) so there is not enough power to produce a high flyweight force, the spring pushes the pilot valve to the fine pitch position.

When the throttle (mp) is pulled below governing power (low engine rpm), the fly weights don't have enough authority to overcome the spring pressure so the prop goes to fine pitch. Now if you pull the prop control all the way aft, the spring pressure is removed from the fly weights allowing the centrifugal force to move the pilot valve to the high pitch position. This is when the prop goes to high pitch with the closed throttle. If the prop control is left at cruise or pushed forward towards high rpm, the spring will overpower the fly weights telling the prop to go towards fine pitch until the blades touch their mechanical stops.

So even when below governing speed the governor is holding the prop in fine pitch. Pull the prop control all the way back and the prop goes to high pitch.

 

[frequent_flyer]

Perhaps the missing piece of the puzzle is the minimum governor speed. I have looked through several Hartzell manuals and have not yet found a specification for the coarse stop governing speed. A flight test a while ago showed minimum governed speed was 1480 rpm. Today's test data showed RPM about 1,300 for the stable descents but run 5 which had the biggest VS excursions also showed large variation in RPM with peaks as high at 1470. Was the prop pitch changing on this test run?

Now I'm wondering if a faster descent could keep the prop in governing range and at coarse setting. If so, could that give a better glide ratio?

 

[skywagon8a]

I have looked through several Hartzel manuals and have not yet found a specification for the coarse stop governing speed.

There is no coarse stop in a governor. The coarse limit within the governor is the fly weights resting against the sides of the "bell" in which they reside. No adjustments are available. The only high pitch stops in the system are in the prop itself.

 

[soyAnarchisto]

Thanks for that explanation - that's a great reminder. I believe in the O-470R I have, my governor is a woodward. I don't know what the governing rpm speed is on each of these governors. Do you guys? Is this a fixed setting or something an A&P needs to inspect/adjust periodically?

So when you are flying - say downwind and you pull the throttle back to idle - the airspeed is still high enough to keep the rpms up and therefore still in the governing range. Does this explain the difference in behavior we are discussing? I understand this to be normal and correct - albeit probably more pronounced in the skywagon because of the larger prop and higher airspeeds. Even at Vg, I can still operate the prop control and really feel that the prop is going fine to course - and the resulting reduction in drag is quite significant. I haven't really been paying attention but I don't think my rpms ever drop down below 1100-1300 even at idle throttle settings until I'm on the ground and done flying - then my idle is around 700 rpm with the butterfly completely closed.

My plane is not currently on floats - I live in Colorado so not much use. I have a hangar down in El Paso so I get down to the southwest pretty frequently in the winter months. If you wanna swap rides some time, I absolutely love flying carbon cubs - and would be happy to demo the seaplane prop on a skywagon.

 

[skywagon8a]

Thanks for that explanation - that's a great reminder. I believe in the O-470R I have, my governor is a woodward. I don't know what the governing rpm speed is on each of these governors. Do you guys? Is this a fixed setting or something an A&P needs to inspect/adjust periodically?

There is just one adjustment on a governor. That is the maximum governing rpm which should be set at full engine red line rpm. Look at your rpm when taking off. If it is correct at the engine's limit ...... all is good. You should never need to adjust the setting between governor overhauls.

 

[frequent_flyer]

There is no coarse stop in a governor. The coarse limit within the governor is the fly weights resting against the sides of the "bell" in which they reside. No adjustments are available. The only high pitch stops in the system are in the prop itself.

I probably used incorrect terminology.

My governor has two stops on the external control lever. One is the adjustable maximum speed stop. The other is a fixed low speed stop. When I pull back the prop lever in flight the engine speed reduces until the governor lever hits the fixed low speed stop.

What I would like to know is the speed that the governor is designed to control to when the lever is on the fixed low speed stop. As I indicated earlier I observed 1,480 minimum rpm in flight. That was after replacing a defective prop control cable that had limited minimum controlled speed to about 1,870 rpm.

 

[skywagon8a]

The other is a fixed low speed stop. When I pull back the prop lever in flight the engine speed reduces until the governor lever hits the fixed low speed stop.

What I would like to know is the speed that the governor is designed to control to when the lever is on the fixed low speed stop.

It's not a speed. It would be a mechanical limitation within the governor itself. I've never come across a governing low rpm (high pitch) limitation or adjustment.

 

[frequent_flyer]

It's not a speed. It would be a mechanical limitation within the governor itself. I've never come across a governing low rpm (high pitch) limitation or adjustment.

I don't understand our disconnect. My governor has a hard stop that limits the lowest controllable engine speed. The governed speed is controllable between that hard stop and the adjustable high speed stop. I cannot accept that the controlled engine speed with the governor lever on the fixed stop is random, unknown, or unpredictable.

 

[skywagon8a]

Does your governor look like this? That long arm is connected to the prop control in the cockpit. The arm rotates clockwise for high rpm (low pitch). The limiting stop is that rectangular piece which protrudes from the screwed on cap. The adjustment for that stop is the screw with a lock nut. That screw is adjusted to set full power rpm to the engine's max limit. There is no adjustable stop which limits the counterclockwise rotation. There are other methods of changing the stop position, but let's not confuse the issue.

It sounds as though you are mixing governor and carburetor controls.

The long arm is the throttle arm. The idle rpm stop arm is the one at 4:30. The adjusting screw is the one at 9:00 with the spring on it. The maximum limit stop is behind the arm at about 7:00 and is not adjustable.

 

[frequent_flyer]

Does your governor look like this? That long arm is connected to the prop control in the cockpit. The arm rotates clockwise for high rpm (low pitch). The limiting stop is that rectangular piece which protrudes from the screwed on cap. The adjustment for that stop is the screw with a lock nut. That screw is adjusted to set full power rpm to the engine's max limit. There is no adjustable stop which limits the counterclockwise rotation. .

My governor is similar but it is not the type you show. I'll try to find a picture later.

I have never said that the counter-clockwise stop is adjustable. I have referred to it several times a fixed stop.

I am VERY familiar with the available adjustment on the governor and the control cable. I made several attempts to get proper stop to stop control before I discovered my control cable was defective and only had about half the proper free travel.

 

[frequent_flyer]

My governor is similar but it is not the type you show. I'll try to find a picture later.

I enlarged a general engine picture and cropped the governor installation. It's not a great photo but the adjustable (high speed) and fixed (low speed) stops are both visible.

 

[spinner2]

I ordered an 83” Trailblazer this summer to go on a 195 hp Titan O-370. Hartzell needed to know all of the engine suffix letters (5 or 6). It was difficult to get that information but I did finally. They said they needed that to know where to set internal stops in the hub. So it isn’t all in the Governor.

BTW they had a mid-year price increase of over 10%. Fortunately I got in under the wire.

 

[Farmboy]

Hey Pete, On the O-360 I fly behind, I don’t believe the trailblazer prop will go off flat pitch below approximately 2000 rpm.
Based on your explanations above I guess I don’t know why, as I just assumed it was oil pressure that turned it coarse, and with low rpm and low pressure it won’t.
So it makes sense that the air pressure is trying to push it coarse, but I’m 95% sure it will not start taking a bigger bite until 2000 rpm or so.


Sent from my iPhone using SuperCub.Org

 

[skywagon8a]

I enlarged a general engine picture and cropped the governor installation. It's not a great photo but the adjustable (high speed) and fixed (low speed) stops are both visible.

It does look as though you have an adjustable stop for both limits. See if you can find a maintenance manual for that governor. There should be setup procedures there. Do you also have the trailblazer prop like farmboy below? It could be possible that particular prop has an rpm or blade angle limiting range for any number of reasons.

Hey Pete, On the O-360 I fly behind, I don’t believe the trailblazer prop will go off flat pitch below approximately 2000 rpm.
Based on your explanations above I guess I don’t know why, as I just assumed it was oil pressure that turned it coarse, and with low rpm and low pressure it won’t.
So it makes sense that the air pressure is trying to push it coarse, but I’m 95% sure it will not start taking a bigger bite until 2000 rpm or so.

The trailblazer prop is a new design. Perhaps they changed the internal control mechanism as well as changing to carbon blades? Is there an air charge in the prop? Next time you fly, close the throttle, set up a glide and pull the prop control all the way back to the stop. What happens?

Aerodynamic forces on a propeller blade creates a blade twisting moment. This makes the blades want to go towards flat pitch. The governor oil pressure forces the blades toward high pitch.

What is the Type Certificate number for that prop? It would be interesting to see if there are any specific limitations. Many prop TCs list particular engine prop vibration limitations.

 

[TurboBeaver]

For what ever it's worth , at Kenmore in late 70's it was standard procedure for the instructor in C-180's to Hank power back when there was an obvious field in sight to make an emergency landing. However they made sure you could NOT make it, without using Pete's explaination: When it was obvious you were NOT going to make it; they would confirm that with you; and say " how bout now" as they pulled the prop control all the way out, and you would lunge ahead ALOT: changing the glide into one, that WILL make the field.......... You try it and you WILL believe it!
E

 

[frequent_flyer]

It does look as though you have an adjustable stop for both limits.

I have reported several times that this governor has an adjustable high speed stop and a fixed (non adjustable) low speed stop.

The maintenance manual for the governor only seems to be available to those with a Hartzell account.

The propeller information is available for anyone to download. https://hartzellprop.com/MANUALS/145-0000-A.pdf

"B. ( )HC-( )( )Y( )( )-1( ) with Composite BladesThese propeller model series (Figures 2-1 thru 2-3)
are constant speed, non-counterweighted propellers.
The propellers are capable of blade angles between a
low positive pitch (low pitch) and high positive pitch (high
pitch). These propellers are sometimes used in aerobatic
applications.
Centrifugal twisting moment acting on the blades moves the
blades to a low blade angle (low pitch) to increase RPM.
Since the centrifugal twisting moment is only present when
the propeller is rotating, a mechanical spring is installed
within the propeller to assist movement of the blades to
a lower pitch position as RPM decays, and to reduce the
propeller pitch to the low pitch stop when the propeller is
static. With the blades at low pitch, the load on the starter
when starting the engine is reduced significantly.
Oil pressure opposes the spring and centrifugal twisting
moment to move the blades to a high blade angle (high
pitch), reducing engine RPM.
If oil pressure is lost at any time, the propeller will move
to low pitch. This occurs because the spring and blade
centrifugal twisting moment are no longer opposed by
hydraulic oil pressure. The propeller will then reduce blade
pitch to the low pitch stop."

Application list specifies this for my prop:

 

[frequent_flyer]

For what ever it's worth , at Kenmore in late 70's it was standard procedure for the instructor in C-180's to Hank power back when there was an obvious field in sight to make an emergency landing. However they made sure you could NOT make it, without using Pete's explaination: When it was obvious you were NOT going to make it; they would confirm that with you; and say " how bout now" as they pulled the prop control all the way out, and you would lunge ahead ALOT: changing the glide into one, that WILL make the field.......... You try it and you WILL believe it!
E

I have no doubt at all that some CS propellers behave like this. I have tested my propeller and reported the results in detail. It does not behave like this.

I care about what the Hartzell Traiblazer with S-1-73 governor does because that's what I'm flying. It stays in fine pitch regardless of prop control position in an idle glide at or below 70 mph IAS. I plan to test whether it comes off the fine pitch stops at any higher airspeed.

 

[skywagon8a]

The fact that there is a spring to assist blade twisting moment does not take away the power of governor oil pressure to place the blades in high pitch. Perhaps this particular governor does not have the ability to boost oil pressure to the normal 300-400 psi? This would be necessary to overcome the spring pressure at a low power setting.

 

[frequent_flyer]

The fact that there is a spring to assist blade twisting moment does not take away the power of governor oil pressure to place the blades in high pitch. Perhaps this particular governor does not have the ability to boost oil pressure to the normal 300-400 psi? This would be necessary to overcome the spring pressure at a low power setting.

1. The lowest controlled speed for my propeller and governor is 1,480 rpm (one test point only so may be some variation from that).

2. Any time there is adequate oil pressure and the engine speed is lower than 1,480 rpm my governor will try to reduce the pitch of the blades to increase engine rpm.

3. My engine speed in a 70 mph IAS glide with throttle idle and prop lever on the aft stop is less than 1,400 rpm.

Does anyone take issue with any of these 3 statements?

Trailblazer owners - what is is your minimum controlled propeller rpm? (My test point was in cruise flight at 20 inch mp and prop control pulled to the aft stop)

Other propeller/governor owners who report glide improvement with prop lever at aft stop - what is your minimum controlled propeller rpm?

 

[hotrod180]

I ordered an 83” Trailblazer this summer to go on a 195 hp Titan O-370. Hartzell needed to know all of the engine suffix letters (5 or 6). It was difficult to get that information but I did finally. They said they needed that to know where to set internal stops in the hub. So it isn’t all in the Governor. ....

Correct.
The TCDS for my C180 with 470K engine & Mac C203 prop
calls out the pitch settings for the blades:
low 10 degrees, high 24.5 degrees for the 88" prop,
and low 12.5 degrees & high 25 degrees for the 82" prop.

 

[frequent_flyer]

Trailblazer owners - what is is your minimum controlled propeller rpm? (My test point was in cruise flight at 20 inch mp and prop control pulled to the aft stop)

Other propeller/governor owners who report glide improvement with prop lever at aft stop - what is your minimum controlled propeller rpm?

I don't think that finding minimum controlled rpm requires a flight test. Next time I take the airplane out I'll run this test prior to the normal run-up and prop cycle:

1. Initial conditions - throttle idle; propeller control full aft
2. Slowly advance throttle while monitoring rpm - expect rpm to rise with throttle advance until a limiting speed is reached
3. Record the rpm and manifold pressure for onset of speed limiting
4. Slowly retard throttle while monitoring rpm - expect rpm to stay constant with throttle retard and then start to fall
5. Record the rpm and manifold pressure for end of speed limiting
6. Pull throttle to idle and set prop level full forward

I'll report my test results here.

I hope a few others with a CS prop will also try this test and report the results.

 

[skywagon8a]

1. The lowest controlled speed for my propeller and governor is 1,480 rpm (one test point only so may be some variation from that).

I think you and I are talking two different things. You appear to be addressing the minimum governing rpm. I'm addressing the minimum rate of descent with the prop in full high pitch and the throttle closed.

 

[soyAnarchisto]

Frequent _flyer,

I think you are confirming that your prop/governor design will not do what we are saying other planes do with constant speed props. Which means if you have an engine out or wish to extend your glide, then you cannot do what we do in our 180s. If in engine out, or at idle your prop is always flat (high rpm, low pitch) then it stands to reason that you are flying with more drag than you'd need or want in an emergency situation. I would not be happy about this.

I can understand the design decision - for if you are at idle with the prop pulled back you certainly do not want to go full throttle in a go around without first advancing the prop lever - but we are all trained to do that with c/s props. It seems they do this so the the starter doesn't have to work as hard. I'd rather have that drag reduction when I need it most - during engine out.

I'm happy to perform the same test and report the result if it would help our understanding at all.

If oil pressure is lost at any time, the propeller will move
to low pitch. This occurs because the spring and blade
centrifugal twisting moment are no longer opposed by
hydraulic oil pressure. The propeller will then reduce blade
pitch to the low pitch stop.

 

[frequent_flyer]

Frequent _flyer,

I think you are confirming that your prop/governor design will not do what we are saying other planes do with constant speed props. Which means if you have an engine out or wish to extend your glide, then you cannot do what we do in our 180s. If in engine out, or at idle your prop is always flat (high rpm, low pitch) then it stands to reason that you are flying with more drag than you'd need or want in an emergency situation. I would not be happy about this.

Yes, it is clear that my FX-3 prop does not behave as others have reported for their aircraft. No surge forward, no amazement, no change in vertical speed.

I'm reasonably sure my prop is in flat pitch at best glide speed because the prop speed is lower than the minimum governing speed. It's not that the prop just happens to be in flat pitch because of some quirk in the design. The governor is commanding it to flat pitch because it's going slower than the set speed.

I would like to know if other FX-3 have the same minimum governing speed and I proposed a ground test. I hope to find out if my FX-3 is typical or has an unusually high minimum governing speed.

Since I cannot get my FX-3 out of flat (fine) pitch at glide speed I think I need to find out what, if any, glide improvement there will be with the prop stopped. Better to find out under controlled test conditions than try to find out in a real emergency.

 

[stewartb]

Frequent _flyer,

I think you are confirming that your prop/governor design will not do what we are saying other planes do with constant speed props. Which means if you have an engine out or wish to extend your glide, then you cannot do what we do in our 180s. If in engine out, or at idle your prop is always flat (high rpm, low pitch) then it stands to reason that you are flying with more drag than you'd need or want in an emergency situation. I would not be happy about this.

I can understand the design decision - for if you are at idle with the prop pulled back you certainly do not want to go full throttle in a go around without first advancing the prop lever - but we are all trained to do that with c/s props. It seems they do this so the the starter doesn't have to work as hard. I'd rather have that drag reduction when I need it most - during engine out.

I'm happy to perform the same test and report the result if it would help our understanding at all.

At flight idle and 70 mph your prop will pitch to course? What's you RPM before and after? My 180's prop governor is unresponsive below 1800 RPM.

 

[frequent_flyer]

I'm happy to perform the same test and report the result if it would help our understanding at all.

I would be very interested to see the results for the ground test I proposed in post 83.

Also - What is the prop pitch on your C-180 with the engine stopped?

 

[soyAnarchisto]

At flight idle and 70 mph your prop will pitch to course? What's you RPM before and after? My 180's prop governor is unresponsive below 1800 RPM.

It will pitch to coarse if commanded by pulling back on the prop control as long as I have oil pressure. I would measure the angle at static engine off, but I'm not an A&P so I'm not entirely sure how to do so accurately (props have twist - where do I measure it and what is the reference)? I believed it is flat when stopped - which is normal. I believe it defaults to coarse when rotating, but without oil pressure which is desirable in engine out and at startup. When the prop stops, I don't think it matters as much unless you dive to twist the prop and get it turning again, again keeping it in coarse due to centrifugal force and the twist in the prop.

I think the only way to know for sure what happens in an engine out is to switch it off, over a field and practice a real engine out. I've never done that for fear of turning a simulated emergency into a real one - but I'm getting pretty comfortable now in this plane, I think it would be worth it to give that a go.

The only thing I'm 100% certain of is the dramatic surge in glide from pulling the prop back to coarse when in the pattern practicing power-off 180 landings. My previous 180 had a 82" cruise prop and I don't remember it being nearly as dramatic as the 88" seaplane prop I have now.

 

[stewartb]

I think the prop goes to flat in the absence of adequate oil pressure, which translates to governing RPM. If your prop goes to course, how do you cycle the prop during the run-up?