Slow to Feather Hartzell Prop

[BigTex]

I've noticed that my Hartzell propeller (HC-C2YK-1BF) is slow to feather the first time during run up. It could take upwards of 10 seconds. The second and third time, it's as expected. This occurs no matter how long the plane sets (1 hour or 1 week).

In flight, the prop works great in flight. No hunting or surging of RPM and there's no evidence of any leakage.

The prop was purchased new in 2006 and has around 500 hours on it.

Any thoughts on what's going on?

[carusoam]

The driver for the "feathering" action is oil pressure generated by a gear pump controlled by a valve attached to fly weights....

Cold oil, low oil level possibly. Since it works as expected the second time....hmmm.

Sounds like the oil drains back to the sump pretty quickly upon shut down. It takes filling the crank back up to apply pressure to the control cylinder.

Thinking out loud....

Hope this helps get some thoughts going...

Best regards,

-a-

[kortopates]

Exactly, the governor is an oil pump that boost oil pressure substantially above engine oil pressure to change the prop from fine pitch to a courser pitch as you pull back on the prop control. However after start up and assuming low power settings as you idle/taxi around, the prop governor hasn't yet been called into action bring the prop back off the fine pitch stops and has not yet built up the oil pressure to do so. The first time you do so takes a few seconds, but 10 seconds is excessive. A couple second delay is more normal. But since there is no hunting or surging, it appears to be operating fine except for the delay in building up oil pressure on first use.

Minor terminology issue but you're c-model prop doesn't feather, not even close, but as you pull it back its certainly changing its pitch to a course angle, but no where near the 90 deg that a multi-engine prop will.

[takair]

What RPM are you doing your prop check at? I notice a longer lag if I do it at lower than 1800 RPM. As Paul mentioned, you need to get oil pumped to the prop to force it coarse. Has it always done this, or is it sudden? Have you changed oil type or viscosity?

[BigTex]

I do the run up at 1800 and the the oil in the plane is Exxon Elite. I purchased it plane about four months ago and it has always taken the first cycle 10+ seconds. I plan on changing the oil over to XC 20W50 and Camguard so maybe that will make a difference.

[stevesm20b]

Sounds normal to me.

[N601RX]

^{The crank snout and prop cylinder cap hold a lot of oil. When the engine is turned of, alot of it drains back into the engine, which has to be replaced the 1st time the prop is cycled after restarting. There is also a filter screen that filters the oil going into the governor. If the governor screen is partially clogged, it will take longer than normal to replace the oil that has drained down. Mine was pretty well clogged when we removed it, unfortunately, you have to remove the governor to get to it, it is made into the gov gasket.}

[rdav]

My M20C reacts in much the same way. I do my runup at 1800 rpm, and notice that it always takes a few seconds longer during the first cycling of the prop. If I recall correctly, there is a noticeable difference on hot vs cold days.

I actually use that as a confirmation that the plane is ready to go. If the prop isn't responding relatively quickly on the second or third cycling, I'll add a fourth one to be certain everything is pressurized properly. Might be overkill, but it boosts my confidence.

[Hank]

The first-time delay on mine is usually just a second or two. If she has sat a long time in the winter, or if it is really cold, it may extend 3-5 seconds. The second time is usually normal. If it is still slow [usually only in the winter], I will cycle it again to achieve a normal response.

My Owner's Manual says:

9. Propeller--CYCLE and CHECK at 1700 RPM.

10. Magnetos--CHECK at 1700 RPM.

[BigTex]

Hank - What you described is what I would expect. I've only owned this plane for going on five months now and all I have to compare it to is a Super Decathlon that I flew. Maybe it's just the engine/prop combination I have and this is normal but just seems excessive to me.

[Hank]

Yours certainly sounds slow. People ask if my 3-blade recovers slow, but I have nothing to compare it against. Other pilots have told me from the right seat that it responds about the same.

Maybe your governor filter screen is clogged? Check it at annual?

[201er]

Can't compare Mooney to Mooney but I remember when I moved up to M20J from Arrow I was surprised at how slow the prop was to cycle by comparison.

[BigTex]

^{There is also a filter screen that filters the oil going into the governor. If the governor screen is partially clogged, it will take longer than normal to replace the oil that has drained down. Mine was pretty well clogged when we removed it, unfortunately, you have to remove the governor to get to it, it is made into the gov gasket.}

I talked to Hartzell and they were scratching their heads as well but as N601RX mentioned, they thought that it would be a look to check the screen on the governor basket to see if it's partially clogged.

[N601RX]

I talked to Hartzell and they were scratching their heads as well but as N601RX mentioned, they thought that it would be a look to check the screen on the governor basket to see if it's partially clogged.

I always thought mine was slow to cycle the 1st time. Unfortunately if it is the gov screen clogged, you may have more problems than the prop cycling slowly. The gov gets its oil after passing through oil after the oil pump and before the oil filter.

[jetdriven]

Repeat the runup and prop cycle at 2200 RPM. Our 1977 M20J, the prop wont cycle at all below 1800 RPM, its slow to respond the first time at 2000 RPM, and at 2200 is quite responsive. This is also a new engine, governor, and resealed prop, so its a characteristic of the type.

[BigTex]

Good point... I'll give that a try and report back.

[carusoam]

POHs for Ovations 1&2, state cycle the prop at 2,000rpm...

Both are Continental IO-550 (G)

Best regards,

-a-

[jetdriven]

Byron,

My '78 J's POH recommends cycling the prop at an unusually high 2000 RPM. I dutifully did this for several years before reading a suggestion from one of the J model gurus on the MAPA List to do it at 1500 RPM instead in order to minimize prop blade erosion and noise. I've been cycling mine at 1500 RPM ever since without any of the delay or more interestingly the non-response issues that you are reporting. I wonder why our aircraft behave differently in this regard.

Jim

IDK but at 1800 RPM or less, the prop will not do anything. At 2000 RPM it cycles OK. I used to fly Barons the same way. Their checklist said mag check at 1700 RPM, and props at 2000. In reality a 1700 RPM mag check would be fine, it is that way for every other O-320, O-360, and IO-360 I ever flew. Note this is the second engine and second governor. The prop was original but just came from the prop shop for a reseal. We have the C214 prop with the rounded tips. I cant imagine that makes it behave differently.

[N601RX]

The differences may be in the governors. There are several approved for Mooneys. They may not all have the same pumping capacity.

[jlunseth]

That's the purpose of cycling the prop in the first place, to get new oil moving through the hub. The old stuff sitting in the line has cooled off and may not move well.

[Seth]

In my former 1967 M20F, I had a three blade prop (already installed prior to purchase and sold that way) and it also, espeically when cold out, took a little bit of time to cycle during the first runup of the day. It responded much more quickly after sitting a short time however - the oil was circulating well at that point. Someone pointed out the slow to repsond cycle when flying, and when I checked with the MSC I use, they stated that the three bladed props take a bit longer to cycle the first time of the day. Now, maybe the two blade takes just a bit less time to cylce due to slightly less oil and pressure needed, so I'm not sure I agree with that completely, but the fact that it's cooler non ciruclated oil the first part of the day does make sense.

My IO-550 powered Mooney M20J Missile 300 has a three bladed full feathering prop, and it doesn't cycle during runup that well unless I take it up to 2000 RPMs to start. I used to cylce the F at a lower RPM (1800 maybe? wow, I have to look back at my old checklist), but the Missile I have to cycle at 2000. It bothered me that it didn't cycle well at the same RPM I used to test my F, and I threfore called Rocket Engineering who said the Missile engine/prop as part of the runup is to be cycled at 2000 RPM. They hold the STC and the information on this thread confirms 2000 RPM is the norm for the IO-550.

Back to the subject - first cycle takes a bit longer as the oil circulates.

-Seth