This is an excerpt from a report made to the Aviation Safety Reporting System. The narrative is written by the pilot, rather than FAA or NTSB officials. To maintain anonymity, many details, such as aircraft model or airport, are often scrubbed from the reports.
During the pre-flight of the DA20-C1 Eclipse, there was icing observed on the control surfaces that was carefully and thoroughly removed. The icing was a result of rain from the previous day that had frozen overnight. I would like to emphasize that all of the ice was removed during the pre-flight phase.
During takeoff, after rotating and becoming airborne, and while increasing airspeed, there was a violent fluttering of the flight controls observed that negatively affected the controllability of the aircraft. The effects were severe enough that I do not believe that we would have been able to successfully complete an entire lap in the traffic pattern to land back at the airport.
Fortunately, the runway was long enough that we were able to make a successful landing on the remaining runway and terminate the flight without further incident.
It was concluded after the flight that the most likely cause was that some of the rain from the day before had made its way into some of the flight control surfaces and caused the fluttering once we reached a high enough airspeed for the imbalance to cause the fluttering.
After temperatures warmed up above freezing, the airplane was flown again without issue.
My biggest issue with this occurrence is that there is really no way to check for icing inside of the control surfaces on any airplane that I have ever flown. As far as I’m aware, the only way to detect this issue is to fly the airplane and observe the fluttering.
Proper corrective action if this is observed in the future would be to abort the takeoff, if able, and if unable to abort, reduce to an airspeed that prevents the fluttering and return to land at or below that particular airspeed.
Primary Problem: Procedure
ACN: 1965711
Freezing weather plus high humidity may have caused additional icing during takeoff. [“After temperatures rose above freezing, the airplane was flown without issues.”] Also, after removing ice, the temperature of the airframe may have been below freezing, allowing new ice to form quickly. Glad the take off did not continue and all are safe.
Nope, there is a way to be certain there is no ice. Put the plane in a warm hangar to allow for all the ice, that which is visible and that which is not visible, to melt off. Also keep the plane out of freezing rain. Put it in a hangar, no matter the cost.
Another way would be to put covers on the wings to keep water out of the ailerons.
The elevator, as a T-tail, is much more difficult to cover, but the controls could be put in full up elevator, so no water can get in.
Actually, putting the controls, particularly the elevators, in the “up” position on some aircraft will aggravate this problem. The drain holes, where they exist, are usually at the trailing edge. When I rebuild fabric acft I usually put an extra set of flat drains just behind the front spar or tube. The typical control lock scenario is to pull back the controls with the seat belt.
The take away here is that your particular aircraft has unique elements. Learn them and account for them. Use your mechanic, CFI, type organization to identify these and the “best” solution.