CEFOSKEY,
Because I work with helicopters
Too true, and I can tell you they are thankfully not the same and some are better than others. Certification standards are the minimum standards and don't infer quality.
Quote Helicomparator
In the case of the first S92 oil system problem that nearly caused a ditching in the Norwegian N Sea, the problem was that when one of the oil pumps stopped being driven, it became a turbine and allowed the oil pressure from the good pump to escape back through the failed pump because there were no check valves. The comment from the designers was "we didn't consider this failure mode".
As Mr Einstein said:
Many of the things you can count, don't count. Many of the things you can't count, really count.
You can never solve a problem on the level on which it was created.
Everything should be made as simple as possible, but not simpler.