Prop torque

[egp8111]

Guys,

Maybe I'm telling you something everyone already knows here but be sure and check the torque values on your Ivo (or anyother for that matter) prop on a regular basis like every 10 hrs. or so. I've found mine to have be under the recommended value by concerning amount a time or two. Composite props are certainly not effected by weather like wood props but seasonal temp changes are bound to have some effect. Being a bit old fashioned I was a little uneasy with Ivo not specifying the prop bolts be lockwired, but it does make it an easy and quick job to check and re-torque.
Like voting, torque early and often !

EG

[DanB]

EG,
Respectfully speaking...I'm not positive that is sound advice. The logic to tighten every so often seems like the thing to do, but I wonder if continuing to crank on those bolts too much would be a bad thing. This is a good topic and I would like to hear from others. What is the consensus?
Dan

[rwaltman]

With a good torque wrench you should not add anything, if the bolts are already at (or above) the specified torque.

Roberto.

PS: A bit of trivia - On my 3-blade Powerfin, which I re-pitched several times in the recent past, I found that of the two bolts around each blade, one and only one needs to be retorqued after ~1 hour at high power settings. Think it was the one on the leading edge side, not sure.

[egp8111]

I didnt say over torque, only check to make sure the bolts are up to the specified values as set on your torque wrench. I agree, you shouldnt go just cranking haphazardly on your prop bolts but with your wrench set to the correct value you shouldnt be adding any tightning to a correctly torqued bolt. On periodic checking of mine I've discovered more than once that over time they had dropped significantly below the torque value the prop manufactor recommend and I just brought them back to the correct value. To each his own.
EG

[Dorsal]

I have my bolts safety wired and check the torque (without removing the SW), so far no changes in 250 hrs. Popper methods may suggest backing off and re-torquing which I have only done at annual time.

[Geowitz]

One notable difference with the IVO(as compared to blades with a hub like a Warp or Powerfin) is that you are actually torquing on the blade sandwiched between aluminum plates, not an aluminum housing. The composite blade is what is actually being compressed and does give slightly, at least initially and possibly beyond that time frame as the engine is run. Rechecking of torque is necessary due to that compression and wearing in/impression setting of the knurled plates. Also, remember that torque is a relative value and does not always correlate with the actual tension(squeezing power) of the bolt assembly - It just happens to be our best guess.

[P Morel]

I'd like to add one more bit of information that has happened to me on two different occasions with my IVO 3 bladed prop. The prop bolts have broken at the shank/thread location due to the shank bottoming out prior to the actual torque value being reached. I never imagined this happening since the spacer washers were installed. As George stated, the composite blade material is being compressed. Check your prop bolts often. I recommend at every oil change at the very least.

[DanB]

Thanks for the posts guys...I also have the three blade Ivo and have only been running for a little over 30 hours now. I checked the torque after running it in the pattern for an hour and it did need a smidgen more. I then checked it again at 10 hours...just a wee bit more. It might be good to check again now, but my concern is over time (say a few years) would it be prudent to continue to compress the composit? Wouldn't the material eventually loose its integrity? Im just surprised to hear the need is out there after a few years go by. When would you know when it's time to replace the blades? Nt really a fan of oops, there goes one
Dan

[Renard]

Dan B brings up an interesting question. Does anyone have any ideas on if/when the blades should be replaced on the IVO prop. I have never heard any of any time/hour line. Is there any check or suggestion other than just waiting till one flies off.

[rwaltman]

Incident report, from the Rotary Wing Forum:

--- WARNING!!! Check your prop bolts! ---
http://www.rotaryforum.com/forum/showthread.php?t=27690