LucasC Posted June 22, 2018 Report Posted June 22, 2018 After my flight yesterday and while cleaning bugs I noticed a little divit about 1/8" wide on backside of prop in meaty section close to spinner area. I brought it up to my mechanic and he is concerned because after inspecting it with one of those jeweler magnification things he noticed a pinhole inside the divit. Prop was OH'd with one new blade and hub in 2005 and has about 700hrs since. What do you think are my options? Does insurance cover things like this? Close up pics below are with magnification. Lucas 1962 M20C
Yetti Posted June 22, 2018 Report Posted June 22, 2018 Does it look like something hit it or did something flake off? @Cody Stallings
LucasC Posted June 22, 2018 Author Report Posted June 22, 2018 looks to be a sharp rock. There has been a lot of drainage excavation work going on at airport. I didn't here it happen so that's just a guess.
carusoam Posted June 22, 2018 Report Posted June 22, 2018 Expect it picked up something from the ground... A really odd spot to get a stone to hit it ..... Looking forward to See what Cody says... Best regards, -a-
LucasC Posted June 22, 2018 Author Report Posted June 22, 2018 1 hour ago, carusoam said: Expect it picked up something from the ground... A really odd spot to get a stone to hit it ..... Looking forward to See what Cody says... Best regards, -a- Really odd spot. Boggles my mind but here we are.
Marauder Posted June 22, 2018 Report Posted June 22, 2018 9 hours ago, LucasC said: After my flight yesterday and while cleaning bugs I noticed a little divit about 1/8" wide on backside of prop in meaty section close to spinner area. I brought it up to my mechanic and he is concerned because after inspecting it with one of those jeweler magnification things he noticed a pinhole inside the divit. Prop was OH'd with one new blade and hub in 2005 and has about 700hrs since. What do you think are my options? Does insurance cover things like this? Close up pics below are with magnification. Lucas 1962 M20C What's the face of the prop look like in this area?
kmyfm20s Posted June 22, 2018 Report Posted June 22, 2018 I have scratched but not chip my prop in that location when putting my cowl back on. Do you have any sharp corners on you cowl that could have done that? Just an idea.
Marauder Posted June 22, 2018 Report Posted June 22, 2018 3 minutes ago, kmyfm20s said: I have scratched but not chip my prop in that location when putting my cowl back on. Do you have any sharp corners on you cowl that could have done that? Just an idea. I was wondering about that as well. If you look at the pictures, there clearly is a scratch headed to the chip.
N6758N Posted June 22, 2018 Report Posted June 22, 2018 27 minutes ago, Marauder said: I was wondering about that as well. If you look at the pictures, there clearly is a scratch headed to the chip. No way could the cowling have made that deep of a crater, this definitely happened with the prop in motion...I fear the worst for that prop blade
Guest Posted June 22, 2018 Report Posted June 22, 2018 I’ve seen damage in this area when a screw fell out of the cowl, but the pin hole at the bottom is interesting. Clarence
LucasC Posted June 23, 2018 Author Report Posted June 23, 2018 3 hours ago, Marauder said: What's the face of the prop look like in this area? Face looks great, no sign of anything.
jetdriven Posted June 23, 2018 Report Posted June 23, 2018 That picture of the damage is on the blade face. I’d have a look at the manufacturer’s specs for blade damage and if there is none, this AC is a good reference. Proceed with caution and sound measurements and data Link https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_20-37e.pdf and relevant section
Cody Stallings Posted June 23, 2018 Report Posted June 23, 2018 (edited) That’s a very Odd place for rock damage. However, depending how many times that Propeller has been O/H that is the thickest part of the blade. That being said, at 2700rpm there is a lot of tonnage being supported in that area. If that nic was 3 inches in from the tip it wouldn’t be nearly as big of issue as it is where it’s at. You will want the bottom(deepest) portion of that damage relived before it has a chance to propagate. Very high Stress in that area. I will attach photo of what that can end up looking like if not addressed. Same area of the blade In my Opinion: Both Blades should be ground in that area to keep weight an aerodynamic contouring between the blades consistent while removing the damage. To do a localized grind on that in the field will take care of the bottom of the damage, but it will also lead to potential balance issues an aerodynamic differences in the blades which cannot be dynamic balanced out. Edited June 23, 2018 by Cody Stallings Picture to Large 1 1
LucasC Posted June 23, 2018 Author Report Posted June 23, 2018 Thanks Cody will relay that to my mechanic. Is this something you’re shop would look at?
Cody Stallings Posted June 23, 2018 Report Posted June 23, 2018 Yeah, we could handle it. We are located in Arkansas, not sure if that is near you or not.
DXB Posted June 23, 2018 Report Posted June 23, 2018 A few weeks ago, I found a gouge on the backside of my prop at an almost identical location to that of the OP's, so his type of damage is not a totally unique event. I thought my defect was tiny -- barely 1/16th of an inch at widest diameter and maybe 1/32 of an inch in depth in the middle of the thick heavy part of the prop - I just ignored and kept flying. I imagine there are are tons of folks flying with this type of damage, though blade failures are a rare event. Now this thread makes me uptight enough look up the specific guidance in my Hartzell's manual posted below. I'm surprised it requires reworking an area almost an inch wide. I presently have nicely balanced blades with minimal vibration .
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