The spectre of ‘Weight & Balance’ follows me about constantly.
Those of you who know me can appreciate that I am easier to walk over
than around. I have the centre of gravity of a weeble, you can knock me
down but I can’t fall over!
And
then, after having stumbled into the helicopter world, I thought I
could concentrate on the more important aspects of my new job. For
various reasons, some of which are described below, it came as a
surprise that W&B is indeed one of the more important topics we
cover in ab-initio flight training. Although I was encouraged by the
cockpit limitations listed for the 206: Minimum pilot weight: 170
pounds (I have that conquered); maximum cockpit weight: 500 pounds
(OK…if I stay between 170 and 500 I have it cinched!).
I know
this may not apply to everybody, but as experience accumulates I
sometimes take W&B for granted. Unlike our fixed-wing brethren, we
can tell pretty easily when our aircraft is overweight or out of
balance just by doing a hover check. It tends to make one a little
rusty on the fine art of W&B calculations and determining if indeed
we are out of limits. My first encounter with the phenomenon of
W&B, and indeed, many of the basic principles of inertia, mass,
etc., came at a relatively early age. While growing up in central
Newfoundland we had a cottage at Sandy Point. Most of the summer was
spent in and on the water and I had laid claim to several large ‘boom
sticks’ which had broken free from their pulpwood corralling duties
up-river and had washed up on our small shore. I joined three abreast,
added a plywood seat amidships and I had my first boat!
The wood
was as close to waterlogged as one could get and still stay afloat and
I added about 30 pounds of nails to keep the scurvy vessel together.
The only part of the boat that showed any enthusiasm for floatation was
the plywood back on the seat.
The weight of the thing was
incalculable and the balance was irrelevant. The specific gravity of
the whole affair was very close to that of water and the deck was
constantly awash, even tractor fore or aft and it would not make any
difference as to how she sat. I christened her the ‘SS Go Nowhere.’
I
fashioned a kayak paddle of sorts, sat on the thing and began to row …
and row … and row. It was difficult to get moving, but once motion was
achieved, it was impossible to stop. I learned very quickly to always
traverse parallel with land because the only way to finish the day’s
sail was to abandon ship and swim ashore. This would allow me to feed
myself and sleep while an onshore breeze brought the beast back to its
launching point. I had a very short memory for traumatic experiences
and all the lessons learned the previous day would evaporate during the
night. A new day would bring a fresh desire for adventure and the whole
affair would repeat itself. This was to the great delight of the
neighbours who found it wonderful entertainment. Mother was neither
entertained nor amused, but simply delighted that I was offshore as
opposed to under foot. This whole affair caused no end of confusion
during my initial pilot training as it came as quite a surprise to
learn that craft of a nautical or aeronautical nature have weight
limitations and are subject to balanced loading. My boat wasn’t, and it
took a while to appreciate that I could not treat the Bell 47G4 the
same as the ‘Go Nowhere.’
While I cannot cite accident data
regarding events which may have been caused by overloading or
out-of-balance conditions, it does not take a great leap of reasoning
to appreciate that too heavy a load drastically affects our ability to
react in an emergency or safely negotiate low-level operations.
Out-of-balance conditions can cause no end of excitement when
struggling with a sloped-ground landing. In a rather interesting role
reversal, some of our light-helicopter clients have recognized the
safety potential of this issue and insist on all cargo and passengers
being weighed before flight to ensure staying within the limits.
Considering we have such little leeway between max gross and empty
weight, we might do well to pay a bit more attention to aircraft
loading (he said sheepishly). In the meantime, I am going back to
trying to save a percent or two of torque by amending the pilot weight.
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