M20E Prop Upgrade Options

[ArrowBerry]

I've been educating myself on Mooney propellers this evening. Firstly, trying to wrap my head around which models and serial numbers are affected by the recurring 100 hour AD. We have the HC-C2YR-1BF from Hartzell with a hub serial number of CH39229B. I understand that we are not affected by the AD because the hub serial number ends with "B", which I've seen referred to on this forum as a "B hub" -- is this correct?

Second question, next year our prop will be due for its mandatory 10 year overhaul. This is a Canadian requirement for all constant speed props regardless of hours of use, no way to avoid it. It makes me wonder what other props are available with an STC for a 67' M20E that would remove the RPM restriction from 2100-2350. I've been cautioned by an engine shop and a couple mechanics to stay far away from this "red range" as it really does trash the bearings and should be respected. We operate at 2450 in cruise for every flight to give us a buffer to account for potential tach errors etc, in an effort to stay far away from this red line!

I want to do some math to see if its better spent money to sell our current prop as is, because in the US the overhaul requirement wouldn't apply, and put that money (and save the cost of the upcoming overhaul) towards a new prop. Our current prop was installed new in 2005, and last overhauled in 2015. I'd have check the book but its low time, less than 400 ish hours since new? And 90% of those hours since 2015.

I've looked at the two blade Scimitar prop as a potential candidate but it also has an RPM restriction for the E, no continuous ops between 2350 and 2550 rpm above 24 inches? Is there anything to gain by switching props, aside from the general sexiness of the scimitar? 

 

Edited August 27 by ArrowBerry

[KSMooniac]

The MT is the only one without an RPM restriction as far as I know. At least for the J models like mine. E/F have a slightly different model 360 without counterweights, so I don't know if it will eliminate the restriction for those models too. It is also dramatically lighter and smoother than every other option.

Sent from my motorola edge plus 2023 using Tapatalk

[EricJ]

48 minutes ago, KSMooniac said:

The MT is the only one without an RPM restriction as far as I know. At least for the J models like mine. E/F have a slightly different model 360 without counterweights, so I don't know if it will eliminate the restriction for those models too. It is also dramatically lighter and smoother than every other option.

Sent from my motorola edge plus 2023 using Tapatalk
 

The Scimitar, at least the two-blade, has no RPM restriction on a J model engine (that's the combination that I have).   Since the engine in an E has a much different crankshaft (with static counterbalance weights), I believe there is still an rpm restriction, but it is different than with the lighter, stock props. 

 

[ArrowBerry]

11 hours ago, EricJ said:

The Scimitar, at least the two-blade, has no RPM restriction on a J model engine (that's the combination that I have).   Since the engine in an E has a much different crankshaft (with static counterbalance weights), I believe there is still an rpm restriction, but it is different than with the lighter, stock props. 

 

Yes it does have a restriction for the E and F models, no continuous ops between 2350 and 2550 rpm above 24 inches MP.

[ArrowBerry]

12 hours ago, KSMooniac said:

The MT is the only one without an RPM restriction as far as I know. At least for the J models like mine. E/F have a slightly different model 360 without counterweights, so I don't know if it will eliminate the restriction for those models too. It is also dramatically lighter and smoother than every other option.

Sent from my motorola edge plus 2023 using Tapatalk
 

Thanks for your response. I was just looking at your avatar picture and noticed you are from Wichita. My partner was at FlightSafety last week for a King Air recurrent and I brought the plane down for the weekend. Had lunch at Stearman field and did a day in Kansas City at the WW1 Museum. The Mooney is such a fantastic plane for travelling! 

 

[MB65E]

Keep that B hub you have. Seems like it should pass OH without issue since the last 2015 inspection. 
-Matt 

[ArrowBerry]

Does anyone have a rough idea what a "B hub" and blades would be worth on the used market in good condition? During a cursory search I couldn't find a single one for sale used to compare to.

I did get a quote from Hartzell, however, on the new two blade scimitar of $15,300 and the three blade option at $18,900 

Holy cow! 

[AJ88V]

You def will want the two blade over the three blade, besides being cheaper.

[MB65E]

I think the hub alone would be worth 5k. 
-Matt

[MikeOH]

No experience with anything other than my stock 2-blade "B" hub on my M20F, but staying out of the 2100-2350 is a piece of cake.  I wouldn't feel the same about the higher 2350-2550 range as I often operate at 2400-2500.  If the prop has that few hours on it, then the OH should be a no issue deal; why complicate and add cost? 

[MB65E]

What’s the deal with the greater than 24" restriction? 

Is that a Canadian thing or a Scimitar STC restriction. 
Im not familiar,

-Matt

[Echo]

3 hours ago, MikeOH said:

No experience with anything other than my stock 2-blade "B" hub on my M20F, but staying out of the 2100-2350 is a piece of cake.  I wouldn't feel the same about the higher 2350-2550 range as I often operate at 2400-2500.  If the prop has that few hours on it, then the OH should be a no issue deal; why complicate and add cost? 

What makes it not so bad is “above 2400mp”. When at 7500 you can’t make 2400mp so it’s a non issue in cruise at altitude. 

[Echo]

3 hours ago, MB65E said:

What’s the deal with the greater than 24" restriction? 

Is that a Canadian thing or a Scimitar STC restriction. 
Im not familiar,

-Matt

STC restriction.

[IvanP]

23 hours ago, ArrowBerry said:

Does anyone have a rough idea what a "B hub" and blades would be worth on the used market in good condition? During a cursory search I couldn't find a single one for sale used to compare to.

I did get a quote from Hartzell, however, on the new two blade scimitar of $15,300 and the three blade option at $18,900 

Holy cow! 

I put the two-blade Hartzell scimitar on my 1970 E few years back when it was time to overhaul the old prop wtth 100hr AD hub. I was very happy with the result. Quieter and smoother operation and better climb rate. The RPM restriction was not a factor on N/A engine - never seen more than 24in MAP at my usual crusing altitiudes (11-14k). I recall that I paid about half of what Hartzell quoted you. The price is steep but may be worth it. 

[ArrowBerry]

On 8/27/2024 at 11:36 PM, MikeOH said:

No experience with anything other than my stock 2-blade "B" hub on my M20F, but staying out of the 2100-2350 is a piece of cake.  I wouldn't feel the same about the higher 2350-2550 range as I often operate at 2400-2500.  If the prop has that few hours on it, then the OH should be a no issue deal; why complicate and add cost? 

I was just curious if it made sense money wise because say in theory our prop is worth $7k with hub and blades, and the cost of the overhaul is $5k, you're already $12k into the new prop... so if you bought the Hartzell for $15k, and spent another $2k on shipping and installation labor costs--you would have to come up with another $5k...

Roughly... I'm guessing on those numbers. But you get the idea. I don't know. That's also a lot of flying gas.

[MikeOH]

21 minutes ago, ArrowBerry said:

I was just curious if it made sense money wise because say in theory our prop is worth $7k with hub and blades, and the cost of the overhaul is $5k, you're already $12k into the new prop... so if you bought the Hartzell for $15k, and spent another $2k on shipping and installation labor costs--you would have to come up with another $5k...

Roughly... I'm guessing on those numbers. But you get the idea. I don't know. That's also a lot of flying gas.

@ArrowBerry

Remember, you're going to spend money on R&R and shipping regardless of OH or buying new.  Also, your analysis assumes you can SELL your old prop to recoup the $7K; if not...even more difference.

I look at it as $5K for the OH plus shipping and R&R vs. $15K new plus shipping and R&R, which is $10K more out of pocket.  If you could really sell the old one for $7K then it would only be a $3K delta.  But do you truly think that's realistic?  I mean, in Canada, is someone going to pay you $7K for a used prop that MUST have an OH?  Even selling it in the US?  No idea what you can get for a used, good condition, but past calendar OH date prop?

But I get it, if you're trying to 'rationalize' having a spiffy new prop.  All of us do that just to 'rationalize' even owning an airplane

[RescueMunchkin]

I have a hub that requires the 100 hour eci. I looked into getting a used B hub but it wasn't economically feasible because the shop would require an overhaul charge to put that hub and prop on my plane. Not sure how that affects the demand of B hubs in general.

[Cody Stallings]

On 8/27/2024 at 11:09 PM, MB65E said:

I think the hub alone would be worth 5k. 
-Matt

$3K as Removed 

[McMooney]

On 8/27/2024 at 11:36 PM, MikeOH said:

No experience with anything other than my stock 2-blade "B" hub on my M20F, but staying out of the 2100-2350 is a piece of cake.  I wouldn't feel the same about the higher 2350-2550 range as I often operate at 2400-2500.  If the prop has that few hours on it, then the OH should be a no issue deal; why complicate and add cost? 

I have the scimitar, the 2350-2550 restriction is hardly noticeable, normal cruise is 23/23 down low and it can't make > 24inches even with ram air above like 7k or 8k

[Bart Chilcott]

I have a new two bladed Scimitar ready to be installed this month on my 65 E model with the IO 360 A1A.  I'll be happy to give a pirep once installed and I have a few flight hours behind it.

[Shadrach]

On 9/4/2024 at 10:40 PM, McMooney said:

I have the scimitar, the 2350-2550 restriction is hardly noticeable, normal cruise is 23/23 down low and it can't make > 24inches even with ram air above like 7k or 8k

That would not work well at all for my SOP in the Mid-Atlantic.

We can an easily make 24” above 7k here in the winter. 
 
If I’m staying low to avoid headwinds, I’m WOTRAO x 2500 and 25-30LOP at roughly 80% power.
23x23 LOP is less than 60%.  

At low altitude, the speed delta between those two settings would be nearly 20mph for my plane.

[Echo]

2 hours ago, Shadrach said:

That would not work well at all for my SOP in the Mid-Atlantic.

We can an easily make 24” above 7k here in the winter. 
 
If I’m staying low to avoid headwinds, I’m WOTRAO x 2500 and 25-30LOP at roughly 80% power.
23x23 LOP is less than 60%.  

At low altitude, the speed delta between those two settings would be nearly 20mph for my plane.

24” is fine. Can NOT exceed 24”. I DOUBT you are getting much over 24”…Just go higher and burn less gas if you do. 

[McMooney]

4 hours ago, Shadrach said:

That would not work well at all for my SOP in the Mid-Atlantic.

We can an easily make 24” above 7k here in the winter. 
 
If I’m staying low to avoid headwinds, I’m WOTRAO x 2500 and 25-30LOP at roughly 80% power.
23x23 LOP is less than 60%.  

At low altitude, the speed delta between those two settings would be nearly 20mph for my plane.

yeah, i never run her above 75% power except for takeoff, esp lop that high.  never bothered to really read the lop/red box thingy so just try to keep it simple.  23x23 per the poh is like 69%.

you are free to run it at 2600, 2700 @whatever rpm or even 

[MikeOH]

14 minutes ago, McMooney said:

yeah, i never run her above 75% power except for takeoff, esp lop that high.  never bothered to really read the lop/red box thingy so just try to keep it simple.  23x23 per the poh is like 69%.

That's ROP.  You can run 23 squared LOP at 8.7 gph for 65% vs. the 10 gph at 69% ROP

[Shadrach]

13 minutes ago, MikeOH said:

That's ROP.  You can run 23 squared LOP at 8.7 gph for 65% vs. the 10 gph at 69% ROP

That’s one impressive engine you have there. 23”x2350 at 100ROP and 9.8gph is 66.1%. Truly amazing that you are only losing 1.1% hp by reducing FF by 1.1 gph and rpm by 50.