Bart asked: > Are we talking about > the same elevator trim mechanism between the split tail and solid > elevator birds and would it make a difference in flutter onset?
In the Sebring crash, the ATP witness reported aileron flutter in both ailerons. We have no indication of elevator flutter in the Sebring crash. That got us talking about flutter in general and I brought up a 1994 crash thought to have been caused by trim tab problems allowing trim tab flutter causing elevator flutter which broke off the empennage. As far as we know, that's the only crash that's thought to have been caused by elevator flutter. As I recall, in the 1994 crash, the investigator commented that the spring on the crashed aircraft may have been too weak to hold the tab against the stop. The strength of the spring should be checked at least annually, IMHO. I'd urge owners to make sure that check is on their personal annual inspection checklist. All the models built with the split elevator have an aerodynamic trim tab on the elevator. As I recall, the D conversion requires the large (later designed) aerodynamic trim tab that was installed on all Ercoupes after serial number ????. So, the discussion of elevator flutter applies to all Coupes. Some early models may still have the bungee system with the crank in the cockpit. Most Coupes now have an aerodynamic trim tab on the elevator. No matter what you have, if the trim arrangement fails, there's a very remote chance of flutter causing a crash. The aerodynamic trim tab is required to have a spring and stop. If the control cable becomes disconnected, the spring will push the trim tab up against the stop and hold it there in the high speed position. The spring and stop are required on the older planes by AD 50-07-01 and the later planes were manufactured with the spring and stop. I'd bet the newer planes MUST have the aerodynamic trim tab with its spring and stop for the plane to be in compliance since they were manufactured that way. Ed
