Nice work as always Ron, even if the data doesn't present any real firm conclusions.

Did you also search "acrobat" in the first pass? Could well be that the person writing a report used "acrobatic" instead of "aerobatic", since the former is, after all, the word used in the regulations.

My Hatz had operating limitations prohibiting aerobatics. Not sure why, I don't know what the policy was in 1987 when it was built, but current policy is for the op lims to say "only those aerobatic maneuvers performed and logged during phase I" may be performed during phase II. No matter that the previous owners had all been doing loops and rolls in it. I applied for and got new limitations for my plane, put it back into phase I for the required 5 hours, and made the required entry listing the maneuvers flown, and am now legal for anything I'm likely to want to do.