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Propeller indexing

P

Postulator

Member
Hello all,

New to VAF. I have a RV6-A with a O-320E2A engine. My IA stated that the prop was not in the proper position to allow for hand propping if needed. I took the prop off to replace the alternator drive belt, explored info regarding proper indexing and found that I cannot index my prop correctly. The master bushing is in the correct position in the crank flange, but none of the four oversized holes are in a position to allow the prop to be horizontal with the engine at #1 TDC. The prop I have was supplied by Van's for this engine. I have not contacted Hartzell or Van's yet, but would like to know an opinion or whether anyone else has noticed this with their engine/prop combination. Thanks in advance.
 
Prop is now at 11:30 as viewed from front. By the time the prop comes down to spot where hand propping can be done, it has already pulled through TDC on compression.
 
Lycoming SB 1098 Q
Read it closely as it is not referring to TDC for crank positioning. They use #1 con rod bearing aligned with the case split line.
Clear as mud.
 
Ralph Inkster said:
Lycoming SB 1098 Q
Read it closely as it is not referring to TDC for crank positioning. They use #1 con rod bearing aligned with the case split line.
Clear as mud.
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That SB details the prop bushing locations and says nothing about the correct propeller location. If his crankshaft does not have the bushings in the correct locations then the prop cannot be installed in the desired orientation.
 
n721dp said:
That SB details the prop bushing locations and says nothing about the correct propeller location. If his crankshaft does not have the bushings in the correct locations then the prop cannot be installed in the desired orientation.
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The bushing is in the correct spot per the SB.
 
n721dp said:
That SB details the prop bushing locations and says nothing about the correct propeller location. If his crankshaft does not have the bushings in the correct locations then the prop cannot be installed in the desired orientation.
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Most props have an indexing hole (wider diameter or flat face) that determines the blade clocking. Check the bushing specs & you can Lycomings preferred prop angles.
 
On the Mooney 201 after the first year of production they indexed the prop to horizontal because it had less vibration. Lycoming even changed the designation, on replacement engines from IO-360 A1B6D to -A3B6D, same engine just a swap on where the indexing bushing is located one hole further around the crank flange.
 
The prop lug bushings on my O-320 with FP prop from Vans do not determine the position of the prop to a specific lug. The oversized lug does however determine the correct position of the ring gear carrier.

The prop had a '0' mark stamped on it and I aligned this with the corresponding '0' mark on the ring gear carrier and this places the prop blades in 11 o'clock and 5 o'clock position, at the start of compression, viewed from the front, which is convenient for hand propping.
 
PaulvS said:
The prop lug bushings on my O-320 with FP prop from Vans do not determine the position of the prop to a specific lug. The oversized lug does however determine the correct position of the ring gear carrier.

The prop had a '0' mark stamped on it and I aligned this with the corresponding '0' mark on the ring gear carrier and this places the prop blades in 11 o'clock and 5 o'clock position, at the start of compression, viewed from the front, which is convenient for hand propping.
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That would be preferable as then the prop could be pulled though to TDC and past TDC to start the engine. My prop is indexed that at TDC, the prop is at 11 o'clock facing the prop. Pulling through in this position is useless as the mag has already fired.
 
I'm going to call Hartzell in the morning and see what they say (if they haven't taken time off for Christmas). I'll post back what they offer.
 
Ralph Inkster said:
Most props have an indexing hole (wider diameter or flat face) that determines the blade clocking. Check the bushing specs & you can Lycomings preferred prop angles.
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Pretty sure that is not correct. Yes there is a larger index bushing, but the larger portion only extends an 1/8” or so from the flange and is for indexing the flywheel, which does have one larger hole for this, not the prop. Some props only have 4 receivers for bushings and in these cases, you may have to move bushings around to change the prop orientation or even buy short bushings that don’t go past the flywheel in some crank setups. Often the index bushing is one of the two short bushings. If you need to move the index bushing around to a location with a receiver on the prop, you will need the special long index bushing. My 540 was that way when i reclocked it.
 
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lr172 said:
Pretty sure that is not correct. Yes there is a larger index bushing, but the larger portion only extends an 1/8” or so from the flange and is for indexing the flywheel, which does have one larger hole for this, not the prop. Some props only have 4 receivers for bushings and in these cases, you may have to move bushings around to change the prop.

Often the index bushing is one of the two short bushings. If you need to move them around, you will need the special long index bushing.
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Your mag should be firing at TDC for starting not 22 to 25 degrees before that is for the running timing.
 
lr172 said:
not understanding your point. I was speaking about props and ring gears, not mags and timing.
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Sorry, somehow my response ended up in the wrong spot. It should have been a response to Postulator after he said about 1100 that his mag had already fired.
 
lr172 said:
Pretty sure that is not correct. Yes there is a larger index bushing, but the larger portion only extends an 1/8” or so from the flange and is for indexing the flywheel, which does have one larger hole for this, not the prop. Some props only have 4 receivers for bushings and in these cases, you may have to move bushings around to change the prop orientation or even buy short bushings that don’t go past the flywheel in some crank setups. Often the index bushing is one of the two short bushings. If you need to move the index bushing around to a location with a receiver on the prop, you will need the special long index bushing. My 540 was that way when i reclocked it.
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Yes, bushing positioning dictate proper flywheel positioning for timing, but also are used on some props for blade orientation. Example Twin Comanche (1 flush / 5 long bushing), Hartzell c/s 360 flange (2 flush / 4 long) as you described & reclocked. Or Sensenich 360 fix pitch aluminum (1 thick long / 5 thinner long, or the 4 c/s long). Other prop brands get around this by machining their prop flanges with wider shouldered holes all around so you could pick your own prop angle.
Note bushings come in various dimensions, narrow shoulders, wider (positioning) shoulders, longer shanks, shorter shanks, depending on what generic or specific aircraft/engine model require.
Or, as you did, reclock it by moving bushings around.
Correct or not
 
Ralph Inkster said:
Yes, bushing positioning dictate proper flywheel positioning for timing, but also are used on some props for blade orientation. Example Twin Comanche (1 flush / 5 long bushing), Hartzell c/s 360 flange (2 flush / 4 long) as you described & reclocked. Or Sensenich 360 fix pitch aluminum (1 thick long / 5 thinner long, or the 4 c/s long). Other prop brands get around this by machining their prop flanges with wider shouldered holes all around so you could pick your own prop angle.
Note bushings come in various dimensions, narrow shoulders, wider (positioning) shoulders, longer shanks, shorter shanks, depending on what generic or specific aircraft/engine model require.
Or, as you did, reclock it by moving bushings around.
Correct or not
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Thanks. Didn't realize they sold the bushing in a version that was .040 wide beyond the shoulder for the ring gear.
 
Norman CYYJ said:
Sorry, somehow my response ended up in the wrong spot. It should have been a response to Postulator after he said about 1100 that his mag had already fired.
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With the current indexing of the prop, the prop is at 11 o'clock at #1 TDC and the mag has already fired, so pulling through to start from that position is just going to be moving air out the exhaust without and compression as that stroke has already come and gone. The prop needs to be horizontal at TDC so that at 10 o'clock you are pulling into compression just before the mag fires. So my prop needs to be indexed about 45-60 degrees opposite the direction of rotation. There is a hole in the prop flange, but it is a small hole that won't accept the master dowel. I guess the master dowel could be relocated, but I'm not doing this until I hear from Hartzell or someone who has done this successfully. The master dowel is in the proper location per the before mentioned SB.
 
Just got off the phone with Hartzell. Their recommendation follows what I have seen. The prop should be horizontal at #1 TDC. The tech stated that they have moved the master dowel around to accomplish this as the dowels can be driven out to repair/replace/reposition. So now that I have some kind of "official" okie dokie, I will move the dowel. Hope this helps anyone else with a similar state of affairs.
 
Not sure what you mean by master dowel, but assume you mean the indexing dowel, the one that is larger than the others. That CANNOT be moved. It can be replaced with the short version if there is no hole for it in the prop or replaced with the long version, but it cannot be moved. Otherwise your flywheel / ring gear will be in the wrong position with no way to set timing.
 
lr172 said:
Not sure what you mean by master dowel, but assume you mean the indexing dowel, the one that is larger than the others. That CANNOT be moved. It can be replaced with the short version if there is no hole for it in the prop or replaced with the long version, but it cannot be moved. Otherwise your flywheel / ring gear will be in the wrong position with no way to set timing.
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Dang! You're right. Back to drawing board.
 
But the tech did say that the master dowel has been moved in some instances. I'm at a loss to see how that was accomplished given the need to maintain flywheel timing.
 
The only way I see that happening is to oversize another hole in the flywheel and marking with witness marks. It is an experimental engine now, and there isn't any balance weights cast on flywheel so there is no reason that can't be done.
 
So, your problem is that there is no hole in the hub where you want the index dowel to be, correct? They sell a version of that index dowel that is short and stops before it protrudes from the ring gear. Replace with that.
 
What nobody has mentioned is that prop starting an A model RV puts your head very very close to the prop as you pull it through. I hand propped our 6A once and I will never do that again with an A model. Better to charge up the battery, replace the starter solenoid or whatever else might be necessary. It ain't worth a prop strike to the noggin. If you aren't getting bad vibration, why not leave it where it is?

Ed
 
Bicyclops said:
What nobody has mentioned is that prop starting an A model RV puts your head very very close to the prop as you pull it through. I hand propped our 6A once and I will never do that again with an A model. Better to charge up the battery, replace the starter solenoid or whatever else might be necessary. It ain't worth a prop strike to the noggin. If you aren't getting bad vibration, why not leave it where it is?

Ed
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Yeah, You think an RV-xxA is bad, I had to hand prop my Mooney once. Of course being short helped a little.
 
Got news for ya…this is a good way to get hurt. Seriously.

Buy a spare starter and at the first hint of a starter issue, replace yours with the spare and get the out of rotation one rebuilt.
Don’t even think about hand propping.
 
Another consideration, hand propping cos of dead battery will lead to a takeoff with a dead battery which might turn out to be another whole level of bad. Alternator either doesn't come on line or works itself to death trying to charge it from nothing and there you are with a dead battery and a dead alternator, and seeing how this kind of stuff works, probably deteriorating weather. :oops:

Ed
 
Mel said:
Unless you grew up with it and know what you're doing!
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Mel, I grew up learning to fly in a Champ and hand starting was easy. But starting an O-320 witho a light prop is a bad practice unless it’s done all the time.
Doing it, because you have a dead battery or broken starter…isn’t a solid idea, even if you grew up doing it.

I’ve started my 4 once, but Champs Cubs, Vagabonds and even my Staggerwing by hand propping…literally thousands of times…that doesn’t make it make sense on an RV.
 
Postulator said:
But the tech did say that the master dowel has been moved in some instances. I'm at a loss to see how that was accomplished given the need to maintain flywheel timing.
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First post you stated you have a O320E2A. According to the SB you should have 3/8” prop bolts and all 6 bushings should be the same length (one with the shoulder a bit wider to index the flywheel for timing). Is this what you have?

Do you have a Hartzell constant speed prop? I wasn’t aware you could install one on an engine with the small 3/8” prop bolts.

If you have a fixed pitch like Sensenich, you should have a spacer between the prop & flywheel that uses a dowel to lock & position them together. Please state what make / model prop you have.

If in fact you have a fixed pitch prop, maybe the Hartzell tech was confusing a master dowel with the indexing bushing we were talking about earlier in this thread. I have never seen a master dowel on a Hartzell prop, but I haven’t seen every possible combination either.
 
Ralph Inkster said:
First post you stated you have a O320E2A. According to the SB you should have 3/8” prop bolts and all 6 bushings should be the same length (one with the shoulder a bit wider to index the flywheel for timing). Is this what you have?

Do you have a Hartzell constant speed prop? I wasn’t aware you could install one on an engine with the small 3/8” prop bolts.

If you have a fixed pitch like Sensenich, you should have a spacer between the prop & flywheel that uses a dowel to lock & position them together. Please state what make / model prop you have.

If in fact you have a fixed pitch prop, maybe the Hartzell tech was confusing a master dowel with the indexing bushing we were talking about earlier in this thread. I have never seen a master dowel on a Hartzell prop, but I haven’t seen every possible combination either.
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My prop is constant speed type and was purchased through Van's. The securing hardware has 5/8" nuts fixed to studs by roll pins. It has 4 holes that will accept the master dowel. It has 2 that are smaller that won't. According to Hartzell, the prop should be horizontal at TDC #1. In order to do that, I will have to relocate the master dowel and enlarge one of the flywheel mounting holes to allow proper flywheel timing at TDC. The tech at Hartzell said that people have relocated the master dowel in the past without any problems, but it will make a certified engine experimental. As mine already falls into that category, this is the path I will take.
 
Bicyclops said:
What nobody has mentioned is that prop starting an A model RV puts your head very very close to the prop as you pull it through. I hand propped our 6A once and I will never do that again with an A model. Better to charge up the battery, replace the starter solenoid or whatever else might be necessary. It ain't worth a prop strike to the noggin. If you aren't getting bad vibration, why not leave it where it is?

Ed
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Not planning on hand propping as a habit. But for that instance where you are stuck... And Hartzell recommends the horizontal position for best balance. There are other balance factors involved like power pulses and the like. I learned at Lycoming school that a prop can be out of balance to the point where YOU don't notice it, but bulbs and aluminum brackets do.
 
justa6ereh said:
Got news for ya…this is a good way to get hurt. Seriously.

Buy a spare starter and at the first hint of a starter issue, replace yours with the spare and get the out of rotation one rebuilt.
Don’t even think about hand propping.
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I'm not going to get into the habit of carrying every possible components that might fail. Might as well drive a one ton truck at that point. I have hand propped planes before. It is definitely the time to have your thinking cap on snug, but can be done safely.
 
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Postulator said:
Not planning on hand propping as a habit. But for that instance where you are stuck... And Hartzell recommends the horizontal position for best balance. There are other balance factors involved like power pulses and the like. I learned at Lycoming school that a prop can be out of balance to the point where YOU don't notice it, but bulbs and aluminum brackets do.
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The problem as I see it is that if the prop is horizontal at TDC hand starting will be very dangerous because you will be leaning down and forward as you pull it thru. It may give you the least vibration there but bad for manual starting.
 
Bicyclops said:
Another consideration, hand propping cos of dead battery will lead to a takeoff with a dead battery which might turn out to be another whole level of bad. Alternator either doesn't come on line or works itself to death trying to charge it from nothing and there you are with a dead battery and a dead alternator, and seeing how this kind of stuff works, probably deteriorating weather. :oops:

Ed
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A fully dead battery may cause problems, but can be brought back to enough life after 30 minutes of charging if you know how. That will prevent problems with charging system, but engine won't start at that level of charge. I'm not new to engines having been a master auto tech for over 40 years.
 
Norman CYYJ said:
The problem as I see it is that if the prop is horizontal at TDC hand starting will be very dangerous because you will be leaning down and forward as you pull it thru. It may give you the least vibration there but bad for manual starting.
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No, that is not the place to hand prop the engine. That is the proper placement of the prop at #1 TDC. That will put the prop at about 10 am (as you face the engine). That will be about 45 degrees before TDC. When you pull the prop through at that point, you are pulling into compression (which you want) and before the mag has fired, letting inertia carry the engine through TDC.
 
Postulator said:
No, that is not the place to hand prop the engine. That is the proper placement of the prop at #1 TDC. That will put the prop at about 10 am (as you face the engine). That will be about 45 degrees before TDC. When you pull the prop through at that point, you are pulling into compression (which you want) and before the mag has fired, letting inertia carry the engine through TDC.
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I thought that the mag fired at TDC when starting not before.
 
OK, I resolve we have a terminology difference, what I (& Lycoming literature) call a crank propflange bushing is what you are calling a dowel. I also resolve your E2A has been reconfigured from 3/8” threaded bushings (standard E2A six long bushings setup) to two short & 4 long 7/16 bushings to accommodate a Hartzell cs prop. I guess I can’t offer advise on juggling the bushing placements to clock your prop to your desired angle.
I can wish you good luck though
 
Norman CYYJ said:
I thought that the mag fired at TDC when starting not before.
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The mag with impulse coupling does fire at TDC. That's why you have to start the process before TDC. You grab the prop at 10am position and give it a yank. The engine then builds compression on its way up to TDC (after bringing air fuel mix into cylinder on previous hand crank), the mag ignites the mixture at TDC and the engine starts. Hartzell's recommendation that the prop be time to horizontal at TDC allows the hand propping to start at 10am position. I don't know how many more ways I can say this. My original question was has anyone else noted the position of their props.
 
Postulator said:
. In order to do that, I will have to relocate the master dowel and enlarge one of the flywheel mounting holes to allow proper flywheel timing at TDC.
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you really need to better processes the advice you are getting here or find some assistance. Your approach is not wise and could lead to engine damage if it results in someone incorrectly setting your timing, as you will have the only lycoming with two index holes in the ring gear. A mistake waiting for an opportunity to present itself.
 
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Postulator said:
The mag with impulse coupling does fire at TDC. That's why you have to start the process before TDC. You grab the prop at 10am position and give it a yank. The engine then builds compression on its way up to TDC (after bringing air fuel mix into cylinder on previous hand crank), the mag ignites the mixture at TDC and the engine starts. Hartzell's recommendation that the prop be time to horizontal at TDC allows the hand propping to start at 10am position. I don't know how many more ways I can say this. My original question was has anyone else noted the position of their props.
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Most 4 cylinder props will stop on compression at 10:00 and left there so you won't walk into the tip of the prop. The only time to place it at 9:00 by hand, is when you park near a taxi lane.... So, just look at all the parked aircraft and notice where the prop sits.
 
I want to thank all who replied with constructive ideas, they have enabled me to come up with a solution to my problem. Happy New Year to all!
 
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