EARLY DT PROBLEM
We are hearing reports of the DT occurring during engine run when using the scroll for a Quick DT. This can be disastrous, resulting in a folded wing and massive damage to the plane. And, there is the danger of injury to those on the ground.
We do not have a quick solution here as the cause can be one of three things.
If we learn of a sure fire way to cure this, we will publish it here. The user is strongly encouraged to carefully check his methods before flying. Run the engine and hold the plane by the tail so typical "in the air" fuselage vibration is present. Test the timer for correct operation. If it is marginal, do not fly. Correct the problem on the ground.
Use of the 3F model timer does provide a sure fire solution to a Quick DT. Use the upper disk for Quick DT during testing, and then move the release line to the normal DT post for regular DT. A number of fliers are doing this.
Something else to watch for is a burr forming on the end of the DT wire where it rests in the scroll grooves. This burr can cause excessive drag on the scroll and cause the time to stop, particularly during the latter part of the DT run.
Some timers will develop a burr on the scroll where the wire exits it, The metal on the scroll is thinner there, and if it gets hit by something, this burr can stop the wire from releasing right at the end of the run. If you see such a burr, simply carefully file it off.