I do agree with Red Baron and Clair, about the use of soft mount, for engines that run at relatively low RPM, as today's pattern, F3A goes, for example. That is, less than 10,000 RPM.

I do understand that noise is a categorical problem and that these expensive soft mounts, do reduce it very significantly.

The break-ups I encountered were headers on TT, OS and MVVS .40-.50 engines, that were mounted on elastomeric, quiet mounts and were pipe equipped to spin at 14,000 to 16,500 RPM. The end of the header was only in the pipe coupler, in all cases. None were rigidly connected to the airframe.

The mounting lug broke (and the opposite one was cracked too) on an old TT .46.

The mounting frame that connects a Textron-Lycoming, or a TCM engine to the body of a full-size Cessna, or Piper is also equipped with elastomeric shock absorbers and grommets, to isolate the vibrations from the airframe.


Let us agree that the cheap soft mounts, when used with high RPM engines, could spell breakage.