On 2010-08-30 6:04 AM, John Cooper wrote:
OK, then why did Erco require the trim tab when installing the C-85 if it is not necessary? For that matter, why did they introduce it at all?
That was the time period when the FAA (and the industry) were realizing it was a darn good idea to have a backup system for all essential controls.
The rudders act as a backup system to the ailerons. On most aircraft, the ailerons can do their job without the rudders (though sloppily).
If the elevator cable(s) break, the spring trim system provides no backup at all. You are dependent on the plane's natural pitch stability and trim with a loose elevator. Bill points out that this should be something controllable. Me, I don't know.
However, with the aerodynamic trim tab, the plane should remain controllable in pitch and airspeed sufficient to make a walk-away landing. With a skilled pilot, the aerodynamic trim should let you get down undamaged.
Ed
