Will master airsrew or the LHS exchange my 14x7 (3 blade)prop for a new one, the engine backfired and it took a small chunk out. This prop has about 15 seconds of run time on it. If not Is it possible to put some epoxy (20 bucks is a lot to just replace it) on the chunk to fix it. lastly how would I balance a three blade.

thanks, dave trimmer

How much will a visit to the emergency room cost compared to the price of a new prop? It's you're choice....

wow, anonymouse put it just right in so few words. I agree with you, $3 for a prop vs $300 for 3 stitches or $3000 for 30 stitches.

That degree of damage is far in excess than what could be dressed out. There is only one way I would ever reuse that prop and that would be trimming all three blades past the damage and rebalancing.

sorry to say that prop is done.
not sure how a backfire could do that unless there was something to strike it on,your using a elec.starter or a chicken stick I have beat my MAS props pretty hard,you might bring it back to the LHS where you got it from they might feel for you,I dont think there is any garentee on there props though.

are you mental?

Sorry you had the backfire, but damage from use isn't something the LHS or mfg should be expected to cover.

And the only safe repair would be what's already been mentioned, shorten all 3 blades and rebalance.

Dave,
I hate to break bad news to you, but that prop is finished. You'll need to replace it. Unfortunately your LHS (or wherever you bought it) isn't responsible for replacing as the damage to it occured from normal use, and not a defect in the prop itself. I know that is hard to hear as it was and expensive prop, but this is just part of the hobby. It's happened to most of us at one time or another.

Ken

Listen to the posts... get a new one... it is part of the game... but if it helps you out... I just ordered a new 3 blade prop for my Giant Scale 40%er.....and it will cost $160!!!!


So just go get a new one and enjoy

Severe and possibly life threatening injurys aside, if that came apart you will likely be looking at severe vibration induced airframe damage before you could shut it down.

i would just get another one, the damage done buy it to you ,someone else, or your plane is not worth it

Here's a good example of what darkbird (and many others) is talking about.

http://www.rcuniverse.com/forum/m_6066924/tm.htm

in the crash and rebuild thread.

Warrantees purposely cover "defects in materials and workmanship", but few seem to understand the explicit limits this places on the vendor.

For example: There has to be a abnormal variance in the plastic, wood or metal used, OR the person ( s ) who put together the item missed, or put in the wrong part... and that's really about it!


If the prop, plane, engine, etc. breaks because of anything you have done or influenced then the manufacturer is under no obligation. The wording is purposely vague to give the vendors the largest possible "out".


Even design flaws are not covered by most warrantees. So if your wings fall off in normal flight, the vendor can claim that the materials used are not defective ( unless you can prove otherwise ), and you are SOL.

To preserve customer loyalty however most vendors will attempt to help you out... and the amount of help you receive in an incident can be influenced by how much you've purchased and what your track record is in making claims.... I.E. the fewer claims you make the more creedence you receive when you make one.

I've seen this happen first hand with companies such as Tower.

Bottom line:

A cut or nicked prop will typically never be replaced by the vendor.

Sorry Dave, time to buy a new prop.[&o]

Dave, any damaged prop should be only used thereafter for stirring paint. Now a chip off the end can be fixed by, just for example, cutting and smoothing off that 14-7 to a 13.5 -7, but it looks like you need a lot more cut off. Of course if you have use for a 11-7 with a wide blade, then A-OK. You can work it out.

NEVER fix a prop with glue. When I was around 14-15, LOOONG time ago, I lived way out in the country, and all was mail order which back then was WEEKS. I had only one 12-6 for that old CL model and that O&R .60. I splintered it about 1/2 way out, but using weldwood (I think) I glued it up. Couple days later, I proceeded to start it up. About 3 pops and I went back on my butt.
That blade caught me right under the left eyelash on the bone just above the eye. I never forget just how close that one was.

NEVER take any chances with anything that can hurt you especially when so close to your eyes. CHUCK it or stir paint.

can anyone figure out the actual weight of each blade spinning at 12,000 RPMs? I bet if anyone can figure that out, a lot of people would think before using a slightly damaged prop.

Uh, the ACTUAL weight doesn't change whether at rest or spinning. The effective weight does. Much like a pilot FEELS heavier when he pulls high G's during aerobatics.

yeah, i was doing some research and (i don't know the actual weigth of each prop blade) the result was 1292 pound force per ounce. So i guess if we could get the actual weigth of the prop blade, we could figure out how much each blade is pulling in centrifugal forces from the prop hub.

if anyone can figure the weight of the prop, here's a good site to get the formula:

http://www.soft-calc.com/calculator/...culator_e.html

If your paying 20 bucks for that prop I would find another place to buy it. As for fixing it I cant add any more then the rest did dont do it but hey its your money and body.

http://www2.towerhobbies.com/cgi-bin...?&I=LXAA40&P=7
and don't forget he is talking about Canadian dollars. Add shipping too.

well, that sucks. and my engine hasn't even got tuned yet! If many of you don't know work has put me at a loss. a year ago it would be ok but with college a year away and work at a low this sucks. I will call master airsrew and see what they will do. as for "sky craft hobbies" in burlington ON. canada, they are a rip off and a half except for fuel. nice guys but harsh on price.

thanks guy for your response, I will see about ordering from tower.

thanks for your help, dave trimmer

I saw this post earlier, before any one responded, but couldn't think of an unsarcastic way of saying just what others have already said.

Failures most often happen during a change of status. That is to say, when going from not running to running and from idle to any other power setting. I'm speaking in very general terms here. That means that this prop will never ever fail as long as you dont start the engine. BUT if you do start it then it might fail in the start up process. Do you want to be right next to it if it goes? If it doesn't fail on start up then it will likely fail when you are messing around with the throttle. Do you use throttle when you fly?? every time you do, you risk failure. If it fails in flight during throttle transition, would this prop maintain proper balance with an inch missing from one blade??? If not then what possible effect could that have on the airframe. Does your plane as a whole cost more or less than the prop alone?

The real question isn't whether or not it CAN be fixed but SHOULD it be. answer those above questions honestly then you tell us whether YOU think it SHOULD be done.