"About three failures of the 1200 hubs" is absolutely unacceptable for a part that is critical for safety of flight. Shipping a part with a nick in the edge of the central hole is unacceptable - period.
Almost all manufacturers use Six Sigma quality control. Six Sigma measures the capability of a process to perform defect-free work. Six Sigma means a failure rate of 3.4 parts per million or 99.9997% perfect. This is the defect rate in the field which includes design, fabrication, shipping, and installation.
3/1200 broken prop hubs is complete show stopper.
Would you fly in a helicopter with parts that had 3/1200 failure rate?
Sorry for the rant...
PPL/ASEL 1970 - Sport Pilot since 2004
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 400
LSRM-A Certificate 2016
Special Thanks to EJ Trucks
Last edited by Piper J3 : 09-29-2018 at 06:03 PM.