[BarryP-51]

I just sanded off material. As I do with every prop. Not sure how this all happened.

[Flypaper]

Could you see any white stress marks on the hub where the blades were attached? A buddy bad a blade depart on an electric Twist 150. Took the firewall off the front taking all the wiring including the batts out of it. Got tail heavy real quick Checking things out afterwards, the blade that was still on the motor had white stress marks about an inch out from the hub, ready to go too. I checked the APC 13-6 prop on my Twist 40 and both blades had the white stress marks. I promptly went to a 13-6 gas/glow prop with the heavier hubs. I think the 3D gyrations are very hard on the props.

[williame3590]

Has to be something to do with the grain and maybe a tempreture factor outside.
Do you know what wood was used and how cold was it outside?
Very strange for sure.

Bill

[Cougar429]

If it was an MA prop it would have been plastic. I have run MA props in all seasons with no problems. Having said that I tell myself this is a hobby and generally refrain from suffering too much when going flying. My Saitos also do not like to turn over when excessively cold anyway.

I've read posts of the APC props coming apart from stress bolted to 4-strokes and I refuse to use them for that app. However, this is the first instance I know of it happening with MA.

If you have any remains other than the hub I would document whatever you can and contact MA about sending the remains back to them. If there is a safety issue lurking hidden we all may benefit from what is found. Due to liability they may not admit to a flaw, but it would hopefully press for a fix.

[Xanadu]

I remember one time where I mounted an APC prop on a prop saver to my hand launch P-51 foamie. The second I hit the throttle(about 1/2 +), the prop immediately tore itself from the prop saver. I heard it hit the ground, so looked down and there it was IMPALED into the ground almost 1/4 the length of the 9x6 prop!
Just missing my foot by 3 inches...........whew....
Never used an APC prop on a prop saver again, they just pulled too muvh torque for the o-ring.

[Guest]

I haven't used a M/A prop in probably 15 years so I can't comment on their current quality, but the reason I stopped using them was countless failures on many club members aircraft over the years. The ONLY props that were worse back then were the white nylon props (can't remember who made them, maybe graupner?)
I saw everything from small 8" diameter M/A props right up to the (then really big) 15" props come apart.
The truth of the matter back then also, was that the black M/A props were so inneficient that we were happy to switch anyway. I never had an APC prop come apart on me, even on the big YS 4 strokes, not to say it can't happen, just never did to me.
As mentioned, I don't know if M/A quality has improved over the years, but I've stayed away from them for a long time and I just can't see myself ever going back to them.

[Arn]

The ONLY props that were worse back then were the white nylon props (can't remember who made them, maybe graupner?)

I remember those .... from back in the late 80's, actually found one in the bottom of my prop box ..... the hub has a moulded MK above what looks like the "Nike" check mark .... no idea who made it ....

Oh did I say that I'm a chronic sufferer of "Pack-rat-itis"

[paulbipe]

I was on the Master Air Screw website and they state: "Maximum recommended RPM for Master Airscrew propellers is 165,000 divided by diameter in inches" that statement is here:http://masterairscrew.com/manualinst...tructions2.pdf. so at 6000rpm you were in the safe limit at the time.

There is a similar statement on the APC site as well. Thought it was interesting. glad that you didn't get your eye damaged. I had a wooden prop (18") break on me due to a blade/earth strike and I found the broken blade at the end of the runway a couple of hundred feet away. They do fly a long distance....hence the MAAC safety rule about getting people out of the prop arc when starting an engine.

Paul

[Cougar429]

I have been running MA props for over 25 years and the only time they have come apart was with a ground strike or when the airplane was following them much deeper into it, (what I call a "Goat"). Nor can I recall any instances of other flyers having a failure. There may have been, but I would expect some prior damage was the culprit.

My only complaint is the work required on their new props to sand off the mold flash, (very sharp) and balancing.

I too remember those white plastic props. Don't know the maker, but also remember they were so flexible you could practically tie them in knots. Never personally used them, but can't imagine they were very efficient. I just recently acquired a few Graupner props and can't wait to see how they perform.

Your reference to the MAAC warning was a good one. I just wish it were enforced more as I see far too many instances of operators or spectators well within the danger zone. There is ABSOLUTELY no reason to lean over top or stand directly in front of the plane when above idle and I cringe at the number of videos posted online taken from that perspective or showing others there.

[Kargon]

The white nylon props that you could tie in a knot were Top Flite, I still have one or two, kept as souvenirs of the 1980's