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converting from fixed pitch to constant speed

J

jeff beckley

Well Known Member
I am kicking around the idea of converting my RV7 to constant speed.
I have a lyc A3A hollow crank. I need some advise as to how i would go about this. Like how do I go about converting the crank and does it have to be removed to install the rear plug. What to look for in buying a used setup. AD's and things. Anything would help me .
 
Your insight as to why you are switching?

I would be very interested to hear why you want to switch. I see FP/CS constantly debated but it is usually more about defending the choice made. You obviously have made the choice to switch so it would be great to hear what about the FP you don't like and why you think CS will be better (as it pertains to your "mission").



Thanks in advance!

Mike
 
charger81 said:
I see FP/CS constantly debated but it is usually more about defending the choice made.
Click to expand...

IMO, many go with the fixed pitch prop because of the initial expense of the constant speed.

I went with the C/S right up front because I knew of all the advantages before hand. I had switched from F/P rentals to C/S rentals a long time ago. There is no way that I would have been content with a fixed pitch RV, and purchasing the Hartzell was probably the number one priority above all else.

Better takeoff performance. Much more choices for landing. Quieter in flight.
Excuses such as C/S maintenance are only that. We re-grease during the condition inspection, and that's about it.

If you just transition from a Cessna 172 or Piper Warrier, to the RV, then you probably wouldn't realize the vast difference between the two props. But if you had flown something more complex, then the difference is quickly obvious... :D

My choice was made from prior & positive "experience". And BTW, I know of no RV owner around here.............who wouldn't prefer a C/S over their F/P. Just stating the facts. :)

L.Adamson ---- RV6A Hartzell C/S
 
Weight diff?

Anyone know the all up weight diff between an alum Sensenich and a two blade Hartzell? I came by a "used" Sensenich and was surprised how heavy it was...
 
It should be around 16lbs.. (Sensenich is 40 and Hartzell around 55 or so)... but you'll almost always gain more if you convert after a while.. somehow planes gain weight over time :)

Been through that process recently.. it wasn't all that bad...
 
I did it on my RV6

Jeff
Feel free to give me a call to discuss this project. I did it on my RV6, but the discussion is more than I care to type.
210 289-3984
 
jeff beckley said:
Right now what i am most interested in is installing the rear plug. What is the procedure for that?
Click to expand...

There is a Lycoming document that cover how to do that.

In short, I made sure the inside of the crank was clean, put a little RTV on the plug, slid it in place - bubble out, took a long square piece of oak that just fit inside the crank, grabbed a four pound sledge hammer and creamed that thing. The trick is to depress the bubble so it pushes the plug outward, sealing the crank.

If you have one of those newfangled cranks with tubes that cross through it, you might have to modify that wood block a bit or use a long socket extension.
 
N941WR said:
There is a Lycoming document that cover how to do that.

In short, I made sure the inside of the crank was clean, put a little RTV on the plug, slid it in place - bubble out, took a long square piece of oak that just fit inside the crank, grabbed a four pound sledge hammer and creamed that thing. The trick is to depress the bubble so it pushes the plug outward, sealing the crank.

If you have one of those newfangled cranks with tubes that cross through it, you might have to modify that wood block a bit or use a long socket extension.
Click to expand...

A crank with the oil tube in the center of the bore really does complicate matters. My hangarmate recently made the switch and before all the old rear plug was cleared out a cylinder had to be removed to pick out the remains of the rear plug that had been pushed down the crank. Be sure you have somebody close by who has experience with working around the oil tube if your engine is so equipped. Getting the old rear plug out is the biggest hassle.

Having said that, Bob loves the C/S prop.
 
Converting from FP to CS

Sam's right the removal of the punched rear plug is challenging. But there are ways to remove the old plug without destroying it and having to remove a cylinder to retrieve the pieces. If there is no rear plug installed then it's pretty easy to install the new rear plug, even around the transfer tube. There may be different configuration crankshafts that challenge this conversion?
Randy
P.S. However, there is also the installation of the external transfer tube, governor adapter, governor, prop control and c/s spinner to do as well...
It was well worth the effort!
 
My crank does not have the plug in the rear. It does have an oil tube that i have to get around. What is the procedure to install the plug when there is a oil tube.
 
I just finished removing my pierced rear plug and the crank has the oil tube. It bypasses the tube easily as the oil tube is off center in the crank. Soon as I obtain the p/n 61510 lycoming plug or equivalent, I'll let you know how easy it is to install.
 
Update--

New plug is installed. Goes in easily---tapped into position with a long brass drift. Worst part was thinking about it so long!!
 
So is anyone finding a bunch of sludge build up in the crank snout when they pull the outer cap off? I have an engine that has no "rear plug", but the crank was packed full of sludge... I can scrape it out, but I fear contaminating the bearings in the process. I will likely just tear down the 350hrs SMOH engine so I can be sure the crank gets properly cleaned.
 
Lycoming "built in" centrifuge and SB 505B

Toobuilder said:
but the crank was packed full of sludge
Click to expand...

I also noticed mine was full of sludge when I went looking to see if I could do a constant speed conversion. I was concerned about having the dregs move backwards and fall in the crankcase, but turned out it wasn't a big deal. I used an old hacksaw blade, plus a narrow nozzle on a shop vac. Broke it loose with the blade, then vacuumed it out.

I thought I was done, but just now noticed a Lycoming service bulletin on cleaning and checking this area, 505B. Much detail here about what to check for. Purely optional for non-commercial flyers, but a good to-do list if you find corrosion. I think I'll go back for a second look, might as well, it is still apart.

This area of the crank reminds me of a bowl centrifuge, a device that works wonderfully at isolating particles that might take weeks to separate at only 1 G. I'd be very surprised if this wasn't the intent of a couple smart old Lycoming engineers. It has a high G environment, almost 200 g's at 2700 rpm, a pond area offering retention time for the oil (widest diameter), a dam (narrowed diameter) is the exit area back into the crankcase for the clarified oil. Only thing that isn't real obvious, how does the fixed pitch engine feed this tiny oil clarifier? Is it the front main bearing or splash though the end? Seems like whether fixed or constant speed, the solids are retained in the pond and removed either at rebuild or when inspecting. Removing the solids seems like a good thing to do once in a while, since once the "pond" fills with sludge, you've got no retention time nor anywhere for the solids to sit, so they are going right back into the crankcase. Once again very impressed by this decades old engine design.
 
Converting my engine back to constant speed

I recently purchased a 'previously loved' IO-360-A1A which was set up for fixed pitch props. It doesn't have the stainless steel (or flexible) oil line, shown below from the Lycoming service bulletin No. 1435 for converting to or from constant speed props. Lycoming wants $500.00 for this part! Is this something that can be fabricated, or do I just need to pony up the cash?

FP06022010A0007S.jpg
 
On my present O-320 that I converted to Constant Speed operation, I purchased a custom 3,000 psi Aeroquip PMA Teflon stainless steel braided hose ($53 USD) from the local Aeroquip supplier.

For the 360 core that I have in my hangar and am building up, I purchased the governor drive adapter and stainless steel line from an RV-9A builder / flyer at my airport that went fixed pitch and says he will never go Constant Speed.

Check the Classified section here on VAF or place a WTB in the classified section here at VAF.
 
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I have the return tube I took off my YIO-320, as I am converting it from a CS to FP. Not sure if it will fit a 360, though.
 
Thanks guys!

Thanks for everyone's help. Bruce fixed me up so I should be good to go.

Lovin' this forum!! Thanks Doug!
 
N941WR said:
There is a Lycoming document that cover how to do that.

In short, I made sure the inside of the crank was clean, put a little RTV on the plug, slid it in place - bubble out, took a long square piece of oak that just fit inside the crank, grabbed a four pound sledge hammer and creamed that thing. The trick is to depress the bubble so it pushes the plug outward, sealing the crank.

If you have one of those newfangled cranks with tubes that cross through it, you might have to modify that wood block a bit or use a long socket extension.
Click to expand...

Not surewhat is meant by ?bubble out? here, but the lycoming install guide shows this to be an interference- fit plug, bubble end in, not out.
See p2 here: https://public.fotki.com/Hartstoc/cs-prop-install-sb-1435/?view=roll
 
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