14 CFR Part 91: General Aviation
Accident occurred Saturday, May 07, 2011 in Conroe, TX
Aircraft: WOODWARD HAROLD L RAVIN 500, registration: N913RA
Injuries: 2 Fatal.

This is preliminary information, subject to change, and may contain errors.
Any errors in this report will be corrected when the final report has
been completed.

On May 7, 2011, approximately 0855 central daylight time, a Woodward Ravin
500 experimental amateur built airplane, N913RA, impacted forested
terrain shortly after takeoff from Lone Star Executive Airport (CXO),
Conroe, Texas.
Visual meteorological conditions prevailed at the time of the accident.
The personal flight was being conducted under the provisions of 14 Code
of Federal Regulations Part 91. The pilot and student pilot rated
passenger were fatally injured. The flight was originating at the time
of the accident and was en route to Temple, Texas, for the airplane to
be displayed at an aviation event.

According to CXO tower personnel, the pilot was cleared to depart runway
14 with a right turn on course. The airplane departed and as the pilot
began his initial right turn he reported smoke in the cockpit. The pilot
was cleared to land on any runway and giving the wind as being from 160
degrees at 8 knots. The airplane was observed to perform an approximate
240 degree right turn and crossed back over the departure runway before
entering the left downwind leg for runway 14. While on the downwind leg
of the traffic pattern the airplane was observed flying,
�¢<80<9Cslow�¢<80<9D, wings level, at an estimated altitude of 700
to 800 feet above the ground. While approximately 4,500 feet along the
downwind leg the landing gear was extended. Shortly thereafter, the
airplane started a descending left turn towards the closer runway 19.
The airplane overshot the extended centerline to runway 19 and the
airplane�¢<80<99s bank angle increased. The airplane continued in the
descending left turn toward the runway until approximately
300 feet above the ground. At which point the airplane appeared to
�¢<80<9Cstall�¢<80<9D and impacted into forested terrain. A post
impact fire ensued. Tower personnel reported that during the event they
did not observe any smoke or flames coming from the airplane until impact.

A pilot rated eyewitness located near the crash site reported hearing
what he described as an engine that was �¢<80<9Cscreaming�¢<80<9D
and varying in RPM. When he saw the airplane it was flying
�¢<80<9Cvery slow�¢<80<9D at an estimated altitude of 300 to 500
feet above the ground. As the airplane made a high bank angle turn back
towards the airport the witness observed the nose and left wing drop
before the airplane went out of sight.
Seconds later he heard it impact trees followed by an explosion.

The airplane came to rest in an upright position about 1,600 feet out on
the extended center line from the approach end of runway 19. The
measured impact heading was 200 degrees magnetic.


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Sounds like they will never know what happened.

I am guessing. One possible scenario is the automotive clutch Bud used
started slipping causing the smoke and the �¢â?¬�?screaming�¢â?¬��
engine. The clutch disk could wear rather rapidly due to normal high
torque fluctuations at high continuous power.

IMHO the TBO on an automotive V8 in aircraft use should be 300 hours.
Any piston engine can develop a crack in the critical parts leading to a
hand grenade failure without warning. The main purpose of the TBO is to
magnaflux the critical parts to detect cracks early before the engine
explodes. Through years and millions upon millions of hours of
experience and detail refinement the TBO on aircraft engines has
increased to 2000 hours.

The TBO on my C182 engine was 1500 hours. By adding another torsional
damper on the crankshaft the TBO was increased to 2000 hours. However
unlike a piston engine in a car the aircraft crank and rods are made of
the finest material possible. Only the best methods of manufacturing and
finishing are used.

Parts in an automotive V8 are made as cheaply as possible as the average
required power is only about 40 HP despite a 400 HP rating.

We are so lucky the Wankel rotary does not see the same kinds of reverse
loading on the e-shaft and the rotor that are seen on a piston engine
cranksaft and rods.
Fatigue failures of the e-shaft and rotor are unheard of.


Paul Lamar



It sounds like the pilot might have stopped flying the airplane, but
instead was trying to save it. My training was that in case of fire, you
get the airplane on the ground immediately, as you really don't know
what's burning. I can understand the smoke could have been
incapacitating, so that might have been the issue, but if it was the
clutch burning, it seems unlikely somehow.


Matt-

I agree but people that build airplanes have so much invested in them
(more than money alone) they appear to be reluctant to crash land
straight ahead as we were all told to do in case of engine failure on
take off. Here is a map of the area and there does not appear to be many
clear fields other than on the airport itself. In the case of rotary
crashes at least two fatals were caused by the pilots attempting to turn
back. In both cases there were suitable fields straight ahead. One
rotary crash was caused by engine seizure after the loss of all oil
pressure due to a split cheap oil cooler and the other an interruption
in the fuel supply due to a poorly designed fuel plumbing system.

IMHO there is another more subtle factor. One is naturally reluctant to
do a 180 and land downwind on a controled airport or busy airport. We
had an incident at SZP where a pilot had an engine failure in a Bonanza
and successfully made a 180 and landed down wind. He slammed it in so
hard on the 2500 foot runway it bent the spar and broke the motor mounts
totaling the airplane but he was not hurt. He skillfully ground looped
it when it looked like he was going to run out of runway at thew other
end. I was standing 50 feet from the point of impact.

I think people should practice 180's at altitude with the engine at
idle. Just to get a feel of what the airplane will do. Note the loss of
altitude.

Paul Lamar

--
Persons close to the parties blame it on a bad oil line connection to
the engine....not the clutch......FWIW....
Marc

Why the "screaming" engine? Or did it sound like that all the time?


Paul Lamar


Have you ever oiled a clutch?


 Mark LaPierre


I can imagine what would happen. Lots of smoke.
Gear box input shaft seal failure?
Good call Mark.

Paul Lamar