Hello Belinda!
I am really sorry to hear of this unfortunate incident but am happy to
hear of your
successful (mostly) off field landing.
I run the Subaru engine as well and have been extremely happy with it
although mine
has been highly modified for more power. I no longer use the NSI redrive
but still have
their dual belt alternator pulley setup. I don't know if this applies to
your situation, but
I have been warned not to get the alternator belt too tight as there are two
of them
in parallel where the engine in the car only has one, putting twice as much
strain on the
alternator bearing. I have noticed that it is actually necessary to set
them fairly loose as
when the engine is hot, all the aluminum in the engine expands a
considerable amount,
tightening the belts significantly. I couldn't believe how much until I
checked the belt
tension right after a flight and they were incredibly tight. I have been
mostly concerned
with cracking the NSI alternator bracket which I have read some reports on,
probably
due to the same overtightened belts.
I had also heard of some seized alternators on NSI Kitfox installations
some years ago
and had been warned to provide good cooling around the alternator. I added
a fairly
large reverse vent right behind the alternator to provide a good flow. My
alternator
does have its own internal cooling fan as well.
I never considered that a seized alternator could stop the engine though.
Thats
a tough one. I'm thinking loosen the belts even more or just use one belt.
That way
at least the engine could still turn.
Sure hate to hear of your loss. I really appreciate the incident report.
I sincerely
hope G-BWCV is repairable!
Glenn
Golden, Colo USA
>From: "Belinda Glover" <belinda@gloverb.freeserve.co.uk>
>Reply-To: europa-list@matronics.com
>To: <europa-list@matronics.com>
>Subject: Europa-List: NSI Subaru owners please read.
>Date: Wed, 2 Aug 2006 23:40:51 +0100
>
>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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