Laggy RPM Knob

[201er]

Is this typical on all Mooneys or do I need this checked out. On Pipers I've previously flown, the response time of pulling the prop knob back during runup felt quick but on my 201, I have to pull and hold it back a few seconds until the RPM drops. It seems to be the same case in flight which has been causing me to pull back too far because at first it wasn't doing anything and then jump too far. I'm getting used to this and the prop control seems to function normally other than the brief delay. So is it normal to have the prop knob back a few seconds while cycling the prop on runup?

[Magnum]

Quote: 201er

Is this typical on all Mooneys or do I need this checked out. On Pipers I've previously flown, the response time of pulling the prop knob back during runup felt quick but on my 201, I have to pull and hold it back a few seconds until the RPM drops. It seems to be the same case in flight which has been causing me to pull back too far because at first it wasn't doing anything and then jump too far. I'm getting used to this and the prop control seems to function normally other than the brief delay. So is it normal to have the prop knob back a few seconds while cycling the prop on runup?

[Shadrach]

Quote: 201er

Is this typical on all Mooneys or do I need this checked out. On Pipers I've previously flown, the response time of pulling the prop knob back during runup felt quick but on my 201, I have to pull and hold it back a few seconds until the RPM drops. It seems to be the same case in flight which has been causing me to pull back too far because at first it wasn't doing anything and then jump too far. I'm getting used to this and the prop control seems to function normally other than the brief delay. So is it normal to have the prop knob back a few seconds while cycling the prop on runup?

[201er]

Doesn't hunt for redline. The slowness isn't that much of an issue to me, just want to make sure it's not an imminent problem or something. I flew a rental arrow, usually first flight of the day. In the arrow it felt like the prop RPM was immediately connected to the knob. The moment I started pulling it back you can see/hear the RPM reducing. In my Mooney when I pull back, nothing happens or a second or two and then it drops quickly to where it was meant to be rather than gradually moving during pull back. A reason for pulling prop back in flight could be going from takeoff to low power cruise at 2000-2200 RPM. That's a long way to turn the knob but without instant feedback it takes a bit more hunting to find the right RPM setting.

Does everyone else have instant RPM feedback?

[bnicolette]

I would not go as far to say it's instant when doing my runup, but there certainly isn't a couple second delay?

Brings up a question for others as well though;  During my runup, I only cycle the prop one time.  I have seen others cycle it three times??  I have been told that one cycle is plenty as the object is to just make sure the prop follows the pull and to put the warm oil in the hub?  This has been working fine for me and makes sense as I am not unnecessarily working the prop, hub, etc. (I guess, I try to be tender with my airplane)  What is every-bodies thoughts on this?

In flight, I never just pull the prop, but rather twist it out and it seems to follow immediately.

[Shadrach]

If I were to estimate....I'd say the vernier controls in every Mooney I've met reduce rpm at something like 150rpm per turn... It's not a long way to turn a knob, it's a non-issue. In terms of control lag,  I am taking off for my Independence Day Celebration around 3:00. IT will only be a 20min flight, but I should be able to get some data points for you then, maybe even some video...

[jetdriven]

mine does that too. I think it is related to the design of the prop and governor. At 1700 RPM, the prop sometimes wont do much at all.  At 2000 RPM, there is that 2 second lag.  Ignore it.

[Shadrach]

OK so I payed close attention to pitch lag whe turning the knob today.  My prop responds in under a sec even at 1100RPM. It took approximately 520 degrees of rotation to go from 2700 to 2550.  I must also state that this is a 2 year old prop governor. The last one did not work as quickly during the run-up. It did work fine in flight. It was removed for a leak and found to be worn out of spec.

Jet, If your prop does not "do much" at 1700 RPM, I'd be leary of the condition of the governor... I was testing mine this afternoon and pulling the control would yield a notable drop at any RPM I tried.

[jetdriven]

I have the Mccauley C290D5 governor and the McCauley B2D34C prop. It is also on the low pitch stop below about 100 knots.  It governs exactly to 2700 RPM for takeoff and down to 2000 RPM with NO hunting. I can assure  you it is a design feature.   Myabe thats why the early J's have 2000 RPM for a mag check and prop cycle setting.  Below 2000 RPM it doesnt really cycle.  At 1500 RPM, the prop does nothing.  No other piston I have flown is like this, except a B 55 Baron as I remember.

[Shadrach]

Quote: jetdriven

I have the Mccauley C290D5 governor and the McCauley B2D34C prop. It is also on the low pitch stop below about 100 knots.  It governs exactly to 2700 RPM for takeoff and down to 2000 RPM with NO hunting. I can assure  you it is a design feature.   Myabe thats why the early J's have 2000 RPM for a mag check and prop cycle setting.  Below 2000 RPM it doesnt really cycle.  At 1500 RPM, the prop does nothing.  No other piston I have flown is like this, except a B 55 Baron as I remember.

[201er]

Is this good or bad? Does it do anything useful or just a lack of additional control?

[1964-M20E]

During run-up mine takes a couple of seconds to respond hot or cold and the knob is out much further than in cruise.  I tend to agree it is an rpm thing at 1700RPM.  I believe the prop is being moved to a higher pitch at lower RPMs since the engine is not developing much HP.  This might be sound physics?  When in cruise just a turn or two and it goes right to 2500RPM.

[Shadrach]

Quote: 1964-M20E

During run-up mine takes a couple of seconds to respond hot or cold and the knob is out much further than in cruise.  I tend to agree it is an rpm thing at 1700RPM.  I believe the prop is being moved to a higher pitch at lower RPMs since the engine is not developing much HP.  This might be sound physics?  When in cruise just a turn or two and it goes right to 2500RPM.

[1964-M20E]

You are correct lower pitch = fine pitch; higher pitch = coarse pitch it relates back to the angle of attack on the propeller.  As for the couple of seconds it may not be that long but there is a lag.  I do not suspect there is anything wrong with my governor.

[jetdriven]

Regarding the 201 governor, maybe the governor wont develop enough oil pressureto the prop hub to make the prop move from the low pitch stop.  It is at a rather coarse setting, as the prop is on the low pitch stop until over 100 knots.