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Lot's of value to cross posting stuff like this Ed. When we look at auto
conversion history, it's clear that loss of electrons is one of the top
10 causes for dead stick. We know there are patterns to failure causes.
If our plane crashes, it will be a repeat of something from history.
In this case, sounds like this guy was flying engine that was last made
in 1981 or so. I wonder if he was using alternator that already had over
1/4 million miles on it?
I've never heard of bearing failure on any modern engine. Regardless of
operating rpm. I suspect this is because of OEM engineers being so
skilled at adding safety margin to each of the components.
I agree, likely engine quit because he throttled back when he noticed
symptoms.
-al wick
Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk assessment, Glass panel design info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
On Thu, 3 Aug 2006 07:36:01 -0400 "Ed Anderson"
<eanderson@carolina.rr.com> writes:
> Here is a story failure mode of an alternative engine on another list
> that
> I found interesting. I rather doubt that stuck belts would cause a
> rotary
> to stop - although if at idle rpm, it just might. I recall one of
> rotary
> flyer who had a bolt jam the water pump pulley, but this caused both
> belts
> to jump off the water pump pulley. No coolant circulating, but
> pilot made
> it back to the airfield, had to make a go-a-round due to conflicting
>
> traffic, but landed safely. Engine was toast but still running when
> he shut
> it down.
>
> Ed
>
> >
>
-------------------------------------------------------------------------
-------
> >
> > Our recently rebuilt Europa G-BWCV is again in pieces after we put
> only 30
> > more
> > flying hrs on this engine to add to the 50hrs it had done in the
> hands of
> > the
> > previous owner.
> >
> > We had just received the new full permit to fly when recently,
> heading for
> > Lundy
> > Island just South of Bristol Docks , the cockpit filled with smoke
> as if a
> > smoke
> > bomb had gone off and the engine stopped! I could not discern
> whether the
> > smoke
> > was electrical in origin but assumed as the engine had stopped it
> had to
> > be.
> >
> > The cause and subsequent sequence of events has now been
> established.
> >
> > Alternator bearing seizure initiated dual rubber v-belt slip at
> the
> > crankshaft
> > pulley.
> > In 2-3 seconds 50 cruise hp turned both rubber belts into smoke
> and
> > vulcanised
> > them instead of driving the now freewheeling prop (no flywheel
> effect to
> > snap
> > belts).
> >
> > The alternator was switched off immediately but to no benefit
> since its
> > load was
> > not the issue.
> >
> > So instead of the crankshaft pulley driving the alternator, the
> alternator
> > now
> > seized was now driving the engine to a stop! A relatively minor
> accessory
> > failure
> > had initiated a cascade of events equivalent or even worse than a
> major
> > engine
> > failure.
> >
> > Ofcourse this should not happen should it?
> >
> > Little did I know I had become an involuntary test
> pilot!!!!!!!with an
> > observer!!!!!
> >
> > The idea of a re-start attempt was not surprisingly quickly
> rejected.
> > However, as
> > I now know it would obviously have been a futile exercise, the
> engine
> > stopped
> > from 50hp running so the starter did not have a chance.
> >
> > Two other aspects of this incident made for an extremely high
> workload.
> >
> > 1. I had to switch off all electrics to prevent any further risk
> of smoke
> > (if
> > only to be able to see out for a forced landing) or worse still
> fire. This
> > meant
> > I lost the electric trim.
> >
> > This may appear a small thing but believe me, this meant the
> constant use
> > of one
> > hand flying the stick without feel and as a consequence one eye
> glued to
> > the ASI.
> > A workload I did not need at this time. Mechanical trim would have
> helped
> > enormously.
> >
> > Try your practice forced landings in cruise trim to see what I
> mean. "It
> > could be
> > you."
> >
> > 2. The other aspect which is a little more difficult to practice
> was the
> > free
> > wheeling prop. All practice forced landings to date had been with
> the
> > engine at
> > idle as is usual. In this condition increasing speed, by diving,
> increases
> > engine
> > rpm so the sprag clutch is effectively connecting engine and
> propeller
> > like any
> > other engine.
> > When the engine stopped, I was quickly aware of an abnormally high
> rate of
> > descent. The prop ran away like a wind generator in hurricane, the
> feel of
> > the
> > stick was abnormal due to the out of trim load and I think also
> the
> > braking
> > effect on the airflow over the tail.of the prop now in drag
> parachute
> > mode.
> >
> > The location was far from ideal for a forced landing and with the
> high
> > rate of
> > descent meaning short time for descent we could easily have come
> off far
> > worse
> > especially since the area was well populated with power lines of
> different
> > sizes
> > forcing a late rejection of the primary field selection.
> >
> > Having taken the diagonal in anticipation of the limited field
> size We hit
> > the
> > far hedge in a 290 meter 30+ Celcius almost max gross with wind
> light and
> > variable as the sea breeze was backing up the Severn valley. The
> near
> > hedge
> > incidentally was a 6 foot steep bank from a wide drainage canal.
> This,
> > coupled
> > with the unusual deck angle in the glide which only got worse of
> course
> > when I
> > put the coupled gear and flap down on the Mono, requiring an
> unusually
> > long
> > duration flare as if landing up hill, put our aiming point
> considerably
> > before
> > the actual touch down point so we were going to hit the hedge. The
> last
> > trick I
> > had up my sleeve from my cross country gliding days was to drop
> the gear
> > in order
> > to minimise the ground roll. This in retrospect, although it did
> no such
> > thing,
> > probably stopped us flipping upside down. I never considered
> applying the
> > brake
> > but the wheel just keeps turning judging by our grass marks.Which
> > fortunately I
> > was able to pace out having vacated the aircraft.
> >
> > I am giving a talk to Gloucester strut about the Europa rebuild
> and now
> > have a
> > new chapter.
> >
> > It is in the Aeros flying club building next Tuesday at 07.30 pm
> and would
> > welcome anyone especially Subaru owners to come along.
> >
> > I still like the Subaru engine and would be happy to fly it again
> once
> > this
> > single point failure has been addressed. If the Europa flies again
> it will
> > be
> > called hedgehog!
> >
> >
> >
> >
> >
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-al wick
Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk assessment, Glass panel design info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
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