I am posting this event on behalf of a friend who does not wish to enter
the conversation directly. It is however a potentially catastrophic
safety issue which should be brought to the attention of the RV
The aircraft, an RV-8 was not built by the current owner… Because he is
uncertain of the extent of possible hidden damage he is replacing the
* Torsional failure of an unbalanced elevator through flutter or metal
* If you did not personally balance your elevators (or trust the person
who did), it is suggested to check the balance.
* When doing so, it is suggested to disconnect the elevator pushrod to
check the balance of each elevator independently.
* Aircraft - RV-8
* Total Time - 580hr
* Conditions - Moderate Turbulance
* Duration of incident flight - 32min
* Airspeed well under Vne due to turbulence.
My friend was returning from a fly-in under turbulent conditions. He
noticed the autopilot release following which the aircraft started to
climb. He reset the trim, reset the autopilot and continued to home
base, about a 20 minute flight. He did not notice any changes to the way the
While putting the aircraft away he noticed some cracks in the right
elevator which he did not notice during the pre-flight inspection. On
further investigation he discovered that the elevator had lost torsional
rigidity and was well on it’s way to complete failure.
He found the right elevator was overbalanced to the front by almost 9
oz. It had the old style weight installed which looks like a rudder weight.
When the video was made, the left elevator did not appear to be cracked and already had the trim tab and motor removed and installed on the new one. As a result, the left elevator was not checked for an accurate balance but appeared to the owner to be slightly underweighted when removed from the aircraft.
It is suggested that it may be prudent to advise owners that have not
built their aircraft of this potential failure mode. Since the state of
balance of the other elevator can mask an imbalance situation it is
suggested that the elevators be disconnected from each other to check
Scale shows 8.7 oz leading edge heavy
Pens point to cracks