Originally Posted by
Paul Cantrell
So, for 30+ years I've been told by various maintenance organizations that the MM ends up requiring 100 hours in Robinson helicopters, regardless of whether they are commercial use or not. I did a bunch of research and must admit that it appears you are correct and that I was wrong. Sorry for the bad information!
I think we would all agree that doing the 100 hr, notwithstanding any possible maintenance errors that might happen in the course of maintaining a machine, is a good thing and represents a reasonable although arbitrary time interval to catch problems. An owner would either be a cheapskate, incredibly lazy or not the brightest bulb in the box to skip it because it isn't a legal requirement. There is nothing magic about 100 hrs. Somewhere back in the mists of the past, someone thought it would be a good interval based on the rates of wear and tear in aircraft that are now antiques.
Maintennce shops are in business to provide maintenance. Of course they will imply 100 hour inspections are truly mandatory because the maintenance manual says so. Robinson and perhaps others say that because they can see the liability issues with some joker flying his toy 400 hours in a year and doing only one inspection. Same thing with service bulletins . A manufacturer can call it mandatory because in their eyes it is, even though regulation doesn't say that unless it is in your ops specs. Think about it. If a manufacturer could actually make something mandatory, they would in effect be legislating. In the US and other places that is not allowed. That is why the Airwortiness Limitations schedule in the maintenance manual is the only FAA approved part of the book. They have made it into regulation by doing so. The type certificate backs that up, as does the US Code of Federal Regulations.