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#1
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Hartzelll 3 blade prop
Anyone here converted an Arrow 180 to a three-blade prop? My flying club recently converted its Arrow when the two-blade prop was found to be shot during its overhaul. The three-blade was cheaper than a two-blade, which seems odd to me still, so that was the choice. The problem is that it vibrates a lot, especially at lower RPM (below 2200). I joined the club just after the replacement so I don't know what the two-blade was like, but it now vibrates a lot more than my Skylane did (I realize the 6 vs 4 cylinder engine likely makes some difference here). However, other club members say it vibrates a lot more. We were told that the prop could be mounted in one of two possible positions, 180 apart and that there was no way to know in advance which position was correct (this also seems odd to me). After the first test flight, the prop was remounted and the vibration was less, but still seems excessive. I'm just curious if others have noticed this. I would have thought the three-blade would have been smoother if anything, but that certainly isn't the case. We're considering taking the plane to a shop that can do a prop balance, but the engine is near overhaul so we're considering waiting until next winter when we'll get both done. Matt |
#2
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if installed properly.. the tach should be marked for non continuous
operation in a range somewhere between 1900 and 2200 RPM.. (don't trust my memory.. look it up) I've flown a 3 bladed arrow.. and yes.. when you pull the power back.. it does vibrate as it comes down through that RPM range.. BT "Matt Whiting" wrote in message ... Anyone here converted an Arrow 180 to a three-blade prop? My flying club recently converted its Arrow when the two-blade prop was found to be shot during its overhaul. The three-blade was cheaper than a two-blade, which seems odd to me still, so that was the choice. The problem is that it vibrates a lot, especially at lower RPM (below 2200). I joined the club just after the replacement so I don't know what the two-blade was like, but it now vibrates a lot more than my Skylane did (I realize the 6 vs 4 cylinder engine likely makes some difference here). However, other club members say it vibrates a lot more. We were told that the prop could be mounted in one of two possible positions, 180 apart and that there was no way to know in advance which position was correct (this also seems odd to me). After the first test flight, the prop was remounted and the vibration was less, but still seems excessive. I'm just curious if others have noticed this. I would have thought the three-blade would have been smoother if anything, but that certainly isn't the case. We're considering taking the plane to a shop that can do a prop balance, but the engine is near overhaul so we're considering waiting until next winter when we'll get both done. Matt |
#3
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BTIZ wrote:
if installed properly.. the tach should be marked for non continuous operation in a range somewhere between 1900 and 2200 RPM.. (don't trust my memory.. look it up) I've flown a 3 bladed arrow.. and yes.. when you pull the power back.. it does vibrate as it comes down through that RPM range.. Our tach was not remarked and there is no placarded prohibited range. Ours vibrates from 2200 down to about 1200. Matt |
#4
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Matt... the rental Arrow POH (in the airplane).. has information for both 2
blade and 3 blade prop installations from the factory... it has the limits on the non-continuous operations in there.. and with a 3 blade prop installed.. the limits should also be placarded and marked in red on the tach.. Sounds like an incomplete installation... unless the STC that governs the installation does not mention it... would be surprising.. The arrow performs nicely with a 3 bladed prop on an ILS approach.. configured and keeping the RPM as desired.. you need to practice the approach speeds and "fly by the numbers".. screw up the configuration.. ie needing idle power to get down to the glide slope and that prop really complains... or when pulling the power during the flare after breaking out at 200ft. BT "Matt Whiting" wrote in message ... BTIZ wrote: if installed properly.. the tach should be marked for non continuous operation in a range somewhere between 1900 and 2200 RPM.. (don't trust my memory.. look it up) I've flown a 3 bladed arrow.. and yes.. when you pull the power back.. it does vibrate as it comes down through that RPM range.. Our tach was not remarked and there is no placarded prohibited range. Ours vibrates from 2200 down to about 1200. Matt |
#5
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Sounds like the prop needs balanced. You have a four cylinder engine with at three bladed prop. The cylinder and prop impulses are oddly synched. More mass and inertia than with the two blace. |
#6
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I did the conversion on my Arrow and had the same problem. I had it
dynamically balanced and rotated 180 and it is now very smooth. There should be a placard to avoid continuous operation at low power settings within a certain range - can't remember the numbers, since it's not a range I normally use for any length of time. Be careful of power off approaches with prop in high pitch. Those 3 blades form a very effective speed brake in idle mode. It's useful to do a crowbar approach while staying above jet vortices but requires some practice. |
#7
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PaulH wrote:
I did the conversion on my Arrow and had the same problem. I had it dynamically balanced and rotated 180 and it is now very smooth. There should be a placard to avoid continuous operation at low power settings within a certain range - can't remember the numbers, since it's not a range I normally use for any length of time. That's encouraging to hear as we're considering a dynamic balance. The prop was already rotated 180 and that made some difference, but not much. No RPM prohibition was mentioned, but that may have been an oversight. Be careful of power off approaches with prop in high pitch. Those 3 blades form a very effective speed brake in idle mode. It's useful to do a crowbar approach while staying above jet vortices but requires some practice. Yes, we learned this very quickly. At less than 1600 RPM the airplane drops like a rock. Matt |
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