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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