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ACCIDENTS AND INCIDENTSFrom CP57, Page 9 (October, 1988)
A TEXAS HOMEBUILDER took
eight years to complete his VariEze. His total experience consisted of about 150 hours in
Cessna 150's and 172's. He had not flown solo for some time. He called RAF and explained
what had happened. He successfully made his first flight, although it was very short and
he had a lot of trouble with pitch control. On the second flight, during the take-off and
climb, he again had difficulty with overcontrolling in pitch. At higher speeds, it flew
great, but when he slowed down to land, he got into a PIO (pilot induces porpoising), got
slow while trying to get it under control, the EZ pitched up then pitched down, crashing
hard on the runway. The nose gear and left main gear were torn off; the prop and lower
winglets were broken.
By his own admission, this pilot said he was anxious to fly, but
he overstepped his ability and his experience. He says, "Don't lie to yourself, don't
fool yourself. If you are not ready, get someone else to fly it and check you out, or get
the necessary training".
We appreciate this pilot's honesty and his guts in calling us
with this accident report. Don't kid yourself into believing you can do it if you know in
your heart that you are not ready - profit by this pilot's experience - it cost him his
airplane and eight years of hard work. Don't let it happen to you.
A CENTRAL CALIFORNIA VariEze experienced in-flight severe
flutter of the elevator and canard which caused a structural failure of the canard, and
the pilot was killed when his VariEze crashed on a wooded hillside. He had about eight
hours in his VariEze before the crash.
He had not built the airplane but had purchased it with all of
the structure done. He then completed the finishing and systems installation. The
elevators were carefully checked for correct balance and some weight was added inboard on
each elevator to bring the elevators into the proper balance tolerance.
Prior to the fatal flight, the pilot had removed the canard to
check something in the nose. Previously, a friend had helped him to install the canard and
noted that he had had great difficulty in getting the canard attach bolts to line up and
thread into the nutplates.
A very careful post crash investigation by the FAA, as well as by
RAF, determined that the probable cause of the catastrophic flutter was that one of the
canard attach bolts was not correctly installed. Either it was not torqued up at all, or
it was cross threaded. In any case, it did not clamp the aluminum lift tab to the F-22
bulkhead. This resulted in the natural frequency of the canard being lowered considerably
since it was only firmly attached on one side. A gust, or something, excited the elevators
driving the canard into a divergent destructive flutter mode.
Although the elevators were balanced, they were very heavy,
having been modified from the original short chord design to the long chord by the
addition of a large, heavy piece of balsa wood and several plies of BID. This caused the
elevators to have a lower natural frequency of oscillation. Thus, these overweight
elevators may have contributed to this accident, however, the primary cause was the
failure of the pilot to properly install the canard.
This tragic accident brings it home to all of us, just how
careful we must be as we work on our aircraft. When you are doing a critical job such as
as installing a wing or a canard or a control surface, you, and only you, are responsible
to ensure that all fasteners are correctly installed and properly torqued. Too often we
get sidetracked while working on a critical installation when we get interrupted by a
friend or passerby. Should this happen to you, do not stop until you have the critical
part installed and safetied - even if you have to be rude to your visitor.
Accidents such as this have been caused by an interruption or
disruption of your thoughts while working on an important aspect of the aircraft. A simple
example is changing the oil. The oil is drained, the drain plug replaced, then a visitor
shows up with a bunch of questions - you forget to fill the sump with fresh oil and -
presto - a destroyed engine when you start it. It happens so easily, it seems so unlikely,
but it happens. Be conscientious, use checklists, be very particular and careful if you
have removed a canard or wing or canopy, etc. Be absolutely certain you have
adequately completed any task you do on your airplane. Last of all, be very
conscientious about doing a thorough preflight on your creation before you commit your,
and perhaps a member of your family's or a friend's, life to your workmanship.
As you know from past Canard Pusher newsletters, the subject of
flutter has been a major concern for years. CP numbers 17,18,19 and 21 have reported
discussions and/or warnings relative to the importance of conformality in the fabrication
of the canard and elevator system. It is extremely important to be aware
that elevators improperly fabricated, too heavy or with the
incorrect bending or torsional stiffness characteristics which result from improper
materials, or fiber orientation, cannot be balanced with any
A mass balance called out for the elevator and the
specification for balancing them, applies only to an elevator fabricated with the same
weight and stiffness as that which has successfully passed all the flutter testing. It is
extremely important, and life-critical, that the manufacturer or owner of each VariEze,
Long-EZ or any plane for that matter, assure, without a doubt, that the control surfaces
are conformal to those which have passed flight tests and been shown to be flutter free.
The advisory shown in the plans change section must be followed
to assure that there are no non-conformal elevators that could contribute to, or result
in, an accident. Do not take this situation lightly. As we have indicated before in the
CP, - IT COULD KILL YOU.!