on june 30, i had an apc 21x10 fail in flight. this prop had never been damaged in any way, but was about 15 yrs old. airplane is an aeroworks edge with a dle 55 engine.failure occured in level flight at 3/4 throttle. blades departed the hub about 1 1/2 inches from the center line. have not found the blades, but do have the hub. this prop was carfully balanced by scraping some material from the top surface near the tip. didn' require much. the throttle pushrod retained the the engine, so was able to glide in without much damage.

This is what we called ECO-friendly props. The plastic degraded early instead of predicted life of 500 years.

I believe that is why APC stopped producing the larger sizes. Too many variables outside of their control, and frankly, I would not trust any plastic prop over 18" in diameter.

I have a APC 18"W but most of my APC's are 16" or under. All my big props starting at 18" are wood and mostly Xoar.

I've run some 12-14" props for some 13 years and never an in-flight failure.

A 21-10 would seem a bit small for a DLE 55. I would be curious to know what kind of RPM it was turning.

15 years? Good Lord man, even full scale props have life limitations. That's why they have a TBO. Anything that flexes is life limited, and time alone impacts life cycle. Look at it this way, you finally have been forced to buy the right sized prop for the engine.......