How do others deal with the restricted rpm zone on landing?

[Bob_Belville]

Reading this thread I'm liking my Hartzell Top Prop Scimitar IO360 combination. The restriction is 2350-2550 when MAP > 24" so it is only a low altitude cruise issue. Oh, it also tweaks the old 25 square climb that we practiced 40 years ago but I usually climb at WOT, full prop. 

[pinerunner]

My 64 M20E has a zone between 1950-2450 RPM with its upgraded prop (no AD, called Hartzell to see if the restriction still applied and they gave me one that was slightly different). I pretty much stay away from that zone and go through it quickly. For landing I pull the power back until it goes out of governance (with prop control full in of course), then lean until slight drop in RPM and then enrich a little (I lean to peak at very low power settings). Then I drop to 1950 RPM to get to under 120 MPH and put the gear down and that initiates descent. I have 1950 RPM and under to play with while descending and if I really need more power I go up to 2450 RPM. They didn't say anything about a low RPM warning zone for my set-up. If I really needed the power I'd get at 2250 when out of governance then I'd use the prop to regulate it down to 1950 RPM and then add manifold pressure, but I haven't really needed that. 

I go full rich on base leg as a habit so the inspector won't freak when I  take my instrument check ride. I do believe in Jonh Deakin's advice that you get in the habit of touching all three controls when making a power increase, but old habits are hard to change. Funny that when I bought it I wanted a COMPLEX aircraft. Now that I've been flying one for a while I try to find ways to make it as simple as possible.

[AaronDC8402]

25 minutes ago, bluehighwayflyer said:

The only folks saying they feel a rumble are '77 J drivers

Our J is a '89 model. 

Per 201er's signature, his is a '78.

[jetdriven]

The C214 was installed in 1978 beucause it has a slightly higher activity factor. It's just a little more efficient.  

This yellow arc thing has been very to death here and on Beechtalk. Finally a Hartzell rep got on there and said maybe 5 minutes or an hour, but for the 2 minutes it take to fly the pattern and land to not worry. 

[201er]

48 minutes ago, jetdriven said:

The C214 was installed in 1978 beucause it has a slightly higher activity factor. It's just a little more efficient.  

This yellow arc thing has been very to death here and on Beechtalk. Finally a Hartzell rep got on there and said maybe 5 minutes or an hour, but for the 2 minutes it take to fly the pattern and land to not worry. 

Does 30x 2 minuters = an hour??

[HRM]

8 hours ago, pinerunner said:

and go through it quickly.

 

9 hours ago, Hank said:

So glide profile and wing design are all what you make of it. 

Yep. ...and here is one reason I love my E:

[Tommy]

The vibration and the noise mean that many J drivers including myself know instinctively when we are in the yellow arc and had been flying some sort of chop and drop method during the base to final leg. But on the very short final just before the fence, I much rather stay on the slope even if it means operating between the arc especially if it's windy or the runway is short. 

Edited November 4, 2017 by Tommy

[jetdriven]

3 hours ago, 201er said:

Does 30x 2 minuters = an hour??

It's not a cumulative thing. And I haven't found any failures of props or engines because of this.  And further there are tons of cardinal RG and Piper Arrows with the same engines and props and no RPM restrictions and none of those have failed either. It's a yellow arc not a redline. Same as your oil pressure gauge has. This I think is another example of self-imposed limitations for no reason. 

[201er]

25 minutes ago, jetdriven said:

It's not a cumulative thing. And I haven't found any failures of props or engines because of this.  And further there are tons of cardinal RG and Piper Arrows with the same engines and props and no RPM restrictions and none of those have failed either. It's a yellow arc not a redline. Same as your oil pressure gauge has. This I think is another example of self-imposed limitations for no reason. 

And is 380/400 degree CHT another silly self imposed limitation for no reason?

[RLCarter]

32 minutes ago, 201er said:

And is 380/400 degree CHT another silly self imposed limitation for no reason?

Not sure about silly, but Lycoming says 435°F (400 for eco cruise) so who is right?

[Andy95W]

23 minutes ago, RLCarter said:

Not sure about silly, but Lycoming says 435°F (400 for eco cruise) so who is right?

The CHT redline on my Piper Aztec was 500° for its Lycoming IO-540s. I guess that was okay in 1967.

[Tommy]

1 hour ago, 201er said:

And is 380/400 degree CHT another silly self imposed limitation for no reason?

Nice strawman you set up there, @201er

Not only your post served no purpose whatsoever in this instance, it actually distracted the whole discussion. Now people are talking about CHTs instead.

Hate to be some sort of forum police but may I suggest that if you had nothing to contribute to the actual discussion please show some courtesy and take your personal vendetta else where. Really appreciate it.

Personally I also disagree with what @jetdrivenis saying but I think our difference of opinion lies in the fact that there is a distinctive lack of firm definition of the term "continuously."  Is it 2 minutes? 5 minutes? 15 minutes? or 60 minutes?

Now if anyone can present a case of failure due to short continuous operation - say 5 minutes - then our ears will all perk up.

Edited November 4, 2017 by Tommy

[PTK]

My Mooney adheres to P+P=P, (Power+Pitch=Performance.) As I'm sure other Mooneys do as well. Prop full hi Rpm (GUMPS) pitch to hold an airspeed (S IN GUMPS) and power to manage descent. Maintaining an adequate airspeed and descent on the approach with P/P will enable the airplane to smoothly transition through the yellow zone rather than linger in it. I have found that the yellow caution zone is only relevant and will cross my mind and I'll glance at it out of habit for a very short time on short final when power must come off for the transition to ground effect.

[midlifeflyer]

On 11/3/2017 at 12:16 AM, 201er said:

It even shakes the camera making it unusable. I rarely operate in the range but you can see it on the approach in this video where being in IMC forced me to operate in the yellow instead of chop and drop. You'll see me make a power change around 16:20 and then it starts to rumble.

 

The vibration is probably a reaction to the music

[Bob - S50]

9 hours ago, jetdriven said:

It's not a cumulative thing. And I haven't found any failures of props or engines because of this.  And further there are tons of cardinal RG and Piper Arrows with the same engines and props and no RPM restrictions and none of those have failed either. It's a yellow arc not a redline. Same as your oil pressure gauge has. This I think is another example of self-imposed limitations for no reason. 

Don't ask why, but I found a POH for a 1971 and 1975 C177RG.  Both have a yellow caution range from 1400-1750 RPM and a normal operating range (green arc) of 2100-2500 RPM.

Instead of an A3B6D like my J, the 177RG has either an A1B6... or A1B6D.  From what I have found, the change from A1 to A3 means the prop is indexed to the engine at a different angle.  Mooney's initially had an A1 engine but they changed it to an A3 engine because it apparently made the engine run more smoothly.

The difference in prop angle might also be the reason for the different caution range.

I also have a POH for an Arrow II.  It has a C1C6 variant of the IO-360.  It has no yellow arc, but it has a red arc from 2000-2350.

 

[HRM]

13 hours ago, 201er said:

Finally a Hartzell rep got on there and said maybe 5 minutes or an hour, but for the 2 minutes it take to fly the pattern and land to not worry. 

What no one has mentioned is the fun you can have with a young whipper-snapper CFI. They panic when the needle goes red. Although some would say I am a glutton for punishment by using the local FBO CFI-du jour-building-airline-time for my FR's, I just have too much fun with them as the last three never flew in a Mooney.

I am not all mean and enjoy showing them what an E can do and confirming what they have heard about the Mooney flying mystique. They always ask if they can land her after the review is over 

[jetdriven]

5 hours ago, Bob - S50 said:

Don't ask why, but I found a POH for a 1971 and 1975 C177RG.  Both have a yellow caution range from 1400-1750 RPM and a normal operating range (green arc) of 2100-2500 RPM.

Instead of an A3B6D like my J, the 177RG has either an A1B6... or A1B6D.  From what I have found, the change from A1 to A3 means the prop is indexed to the engine at a different angle.  Mooney's initially had an A1 engine but they changed it to an A3 engine because it apparently made the engine run more smoothly.

The difference in prop angle might also be the reason for the different caution range.

I also have a POH for an Arrow II.  It has a C1C6 variant of the IO-360.  It has no yellow arc, but it has a red arc from 2000-2350.

 

How about the Arrow IV with the IO360 C1C6?  I fly one of those often, and it has a C212 Prop, and no yellow bands on the tach.

The C1C6 only differs from the A1B6 the fuel injector bolts on to the sump backwards. Its the same engine.

 

Lets look at data, since thats the reason we do or dont do things. We dont run the engine contnuouslty above 400F CHT because that shortens the life of cylinders.  But can you find a single prop or engine failure due to running one of these planes in the yellow RPM band for landing? 

Edited November 4, 2017 by jetdriven

[flyboy0681]

On 11/2/2017 at 11:28 PM, 201er said:

I avoid the yellow arc more so because it is rumble and uncomfortable than the restriction. 

Same here, I always feel uneasy with the vibration produced at those power levels, thinking the engine is going to shake off of its mounts.

[bradp]

For those who think the engine is going to depart the mount- do you have a sawed off prop or a curvy one.  Dorn told me one day it was the straight props that experience the vibration.  He’s flown more Mooney’s than almost anyone so I’d trust his input. 

[bradp]

Jim sounds about right.  I have a 77 J with a 214 and a B6 conversion and I get some pretty minimal vibration in the yellow band. 

I sat in a 3 blade MT early 80s and there was no vibration to speak of.  

[Tommy]

Is it just the vibration that matters? Or are there other concerns to speak of?

[jaylw314]

On ‎11‎/‎3‎/‎2017 at 6:05 AM, mooniac15u said:

For the M20J:

"Engine tachometer is to be marked with a YELLOW arc between 1600 and 1950 RPM indicating a caution range against continuous operation in this speed range with manifold pressure below 15" Hg"

For 201 drivers, how does this end up being an issue at all on descent?  with the gear down, I'm doing a normal descent at about 17" Hg, and full RPM (around 2100, I think).

On the other hand, I wonder if this is an issue during run-up?  I can't remember what MP you end up at for 1800-1900 RPM during the run-up, and I don't have a working plane to double-check...

[flyboy0681]

1 minute ago, jaylw314 said:

For 201 drivers, how does this end up being an issue at all on descent?  with the gear down, I'm doing a normal descent at about 17" Hg, and full RPM (around 2100, I think).

On the other hand, I wonder if this is an issue during run-up?  I can't remember what MP you end up at for 1800-1900 RPM during the run-up, and I don't have a working plane to double-check...

You must be a way better pilot than me, and to  have the good fortune of landing without any wind! To be able to set power at 17" and just leave it there must be an incredible feeling.  

 

[jaylw314]

15 minutes ago, flyboy0681 said:

You must be a way better pilot than me, and to  have the good fortune of landing without any wind! To be able to set power at 17" and just leave it there must be an incredible feeling.  

 

Well, it is if you use pitch for airspeed and power for descent.  And I do full-flap touch-and-goes while LOP

All jest aside, I find I need more than 15" MP while flying in the pattern until short final in an M20J, so the caution range is only an issue while in cruise descents.

[Hank]

1 hour ago, jaylw314 said:

All jest aside, I find I need more than 15" MP while flying in the pattern until short final in an M20J, so the caution range is only an issue while in cruise descents.

You reduce throttle for cruise descents? All i3 do is push the yoke for 500 fpm and retrim . . . The caution zone on the tach never comes into play.