> I would like to report a broken housing due to a
hard landing.
> Actually, in
> my case it was a wave on the water, same
consequences. Included are
> pictures to show the details. I use Tracy's
redrive and adapter
> plate. I
> have one engine mount under the adapter plate.
The force applied
> to the
> mount applies a force on the engine rear housing
right at the oil
> filterboss. My rear housing broke at the dowel
hole next to the
> oil filter boss.
> The new rear housing I bought is stronger in that
area, there is
> more metal
> around the dowel hole. One photo shows the broken
housing and where
> I tried
> to weld it. One photo shows where the forces are
applied. One
> photo shows
> the new and old housings.
>
> Rino Lacombe
> I am a bit skeptical that a hard landing caused
this. In order to
> do that
> all the other ten MM bolts holding the PSRU plate
to the engine
> throughthe spacer would have to deflect. This
dowel hole has been
> known to crack
> in car use. That is why Mazda beefed it up in the
third gen engine.
> Whattype of intake system are you using? It is a four
> port engine. Is it a turbo charged four port? NOS?
>
> Paul Lamar
>
> Did the engine ever back fire Rino?
>
> Paul Lamar
Rino,
Did the bridge for your rear plyon mount sustain any
damage? (this is the single, center mount for
non-Glass Goose types). It would seem that this
relatively flexible mounting structure would have a
hard time imparting large enough loads to break the
rear engine housing.
Could you tell if the housing break seemed to be
from a compression force (upward/forward) shoving
the redrive into the engine, or a
bending/distraction force (aft displacement of the
break) from the rear mount acting as a fulcrum
between the engine and redrive?
BTW, how has your cooling system been working? Any
other flight or engine performance you'd like to share?
Scott Gettings
Or torsion. Torsion is the usual failure mode as that dowel
pin is subject to all engine torque. Detonation can also
cause these kinds of failure.
Paul Lamar
Very interesting Paul. I did end up with one broken apex seal on the front
rotor!
I did not hear detonation and I have no gauge.
I am using Tracy's engine controller and the timing was about 10 deg. BTDC.
I also know that at wide open throttle the engine was surging which I
interpret as too lean mixture.
Two things must have happened at the same time, detonation and hit the wave
because right after hitting the wave the engine stopped and the oil spilled
out. The wave hit hard enough to damage the trailing edge of the two
sponsons and some minor damage to the hull (bottom of the boat).
Paul, I included a photo of the intake system and the turbo. It is a
turbocharged four ports 1988.
Scott, a bad landing that would hit that hard would probably end up with no
landing gear left under the plane. The plane went flying for a minute or
two.
When I removed the engine, that is the first place I looked for damage, rear
pylon mount. I had painted the mounts when I made them so that stress
points would show better. There is no sign of stress on any part of the
two mounts, I must say that I was surprised. The propeller did touch the
deck and made a small dent. It was not high enough, only 3/4", I raised to
1-1/4".
Scott, I cannot comment on the cooling system, the plane did not fly yet. I
was away from it for about 14 months, building a house. I hope it will fly
in a couple of weeks. The engine is back in the plane with apex seals from
Tracy. I cannot tell what kind of force was applied to the rear housing.
Rino
-------------------------------------------------------------
Ah Ha broken apex seal and turbo! Strong indication of detonation.
It is easy to make a detonation monitor with an amp and
ear phone. I'll upload a schematic if anyone is interested.
Also MSD sells one with a visible indication of detonation.
Unfortunately once it happens it is usually two late.
Were you using 3 piece 2 mm seals? Do you have an intercooler?
Also it is possible a prop strike could break that end housing
Prop strikes usually crack an aircraft piston engine's crank.
Since the oil squirted out right after it hit the prop
strike is a more likely scenario for breaking the end housing.
Paul Lamar
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2005 All world wide rights reserved.
