Hi Steve,
Let's put this "greater chance" thing, which is correct, into
perspective as an overall and properly comparable risk.
First off, any aircraft design with tankage above the centerline of the
engine (i.e. all that have gravity fed systems) have a "greater chance"
in hard contact with terrain, etc. that ruptured tanks will spill fuel
on a possible ignition source. Balancing that should be statistics
that show aircraft designs with gravity feed fuel systems have a
significantly reduced chance of off-airport landings resulting from
fuel pump or electrical failures.
The Ercoupe is a hybrid, of sorts, since our "fuel pump" does not
directly supply the engine with fuel, but serves instead to transfer
fuel from tanks mounted low in the wings to the higher fuselage tank.
Accordingly, the five or six gallons in the fuselage tank would
logically pose a somewhat lesser threat than high wing designs that
carry most fuel directly above the cabin and its occupants.
Many of the high wing designs have "conventional gear", and so if not
flown so as to touch down fully flared at minimum speed would quickly
tip forward and flip alighting on a soft surface with more vertical
velocity. Aircraft with tricycle gear, as Linda has recently
demonstrated, can touch down in a freshly plowed field. The tricycle
gear actually helps to prevent nose-over and flipping so long as the
landing is not at high speed and a full flare is possible prior to
contact.
The "bottom line, here, is that the pilot's goal should be to reduce
forward speed to a minimum and land aligned with and not across furrows
or other features of terrain. Then, even if the nose gear does
collapse, there should be insufficient forward energy to rupture any
tanks. When landing on water it would seem that the risk of fire would
be minimal, but one would still best either land aligned with the waves
or try to touch down in a trough to minimize the danger of being
incapacitated by impact and to assure that the aircraft structure
retain maximum buoyancy as long as possible.
On the other hand, if one is in a high density altitude condition and
takes off but cannot climb, the possibility of flying into rising
terrain at full power is a real one likely to result in fatalities.
Accident statistics that include post-crash fires following essentially
uncontrolled impact should be omitted from any evaluation of dangers
posed since risk that is not or can not be "managed" reduces any result
to one of mere "luck of the draw", the study of which would seem
pointless.
In any survivable accident, I believe it to be unlikely that the
firewall will push back so as to rupture the fuselage tank. The danger
I see is that the steel control column mounted vertically just below
the fuselage tank is driven upward into said tank with sufficient force
to rupture a seam (and cause a spark?) or fuel then escapes onto radios
mounted below the panel. I don't know if gasoline could short out a
radio, etc.
In every case, then, it would seem that the risk genuinely posed is
best managed by getting instruction and maintaining proficiency in
engine-out procedures that assure (in most cases, not all) that
touchdown is at low forward speed and near zero vertical speed.
Regards,
William R. Bayne
.____|-(o)-|____.
(Copyright 2010)
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On Jul 10, 2010, at 14:17, ke1lg wrote:
On another GA Yahoo group I belong to,someone remarked that the
Ercoupe, especially the 415-C, had a greater chance of fire during
off-airport/rough-field landings due to collapse of the nose gear, and
the firewall pushing the fuse panel into and igniting the header tank.
He even said he personally knew of two pilots who had lost their lives
to fire in that circumstance. As a prospective 'Coupe owner, and
ex-Luscombe driver, I am really curious if their is any truth to that.
My guess is that this has been discussed before, but I have been
unable to find any archive information on the topic.
Many thanks,
Steve in Maine
