stuff up his descent this badly?
Of course I don’t know what he
was doing, but whatever it was,
it makes a strong argument for
keeping the threshold within
gliding distance, especially when
the tanks are low.
Anyone who has f lown a
C210 will know that if you put
out the gear and full f lap, the
aircraft doesn’t so much descend
as plummet. But this may not be
what actually happened at all. The
CAA have once again excelled
themselves with a really crappy
investigation here – so the "facts"
may not be facts at all.
So, we have this experienced
pilot thinking he is very high on
base leg. Then he sees that he is
not too high at all – in fact he is
not going to get to the runway. He
opens the throttle, but nothing
happens, so he throws it in a field.
But wait a minute – the wheels
were up when he landed. Why
would that be? He was on right
base for landing on 11, and he was
too high. Surely he would have
had the wheels down?
OK, now let’s look at the
Cessna-specific fuel problems,
which are largely caused by
two things. The first is that the
small dihedral means that the
ball doesn’t have to be far out of
the middle for the fuel to move
laterally in the tanks. Second,
Cessnas–for reasons that I don’t
fully understand–are inclined to
allow fuel to cross-feed both on
the ground and in the air.
On the ground, this means that
the aircraft must be absolutely level
when you refuel, otherwise you are
in danger of not properly filling
the tanks. In fact, I have it seen
it recommended that after filling
both tanks, you then top up the
first tank again because while you
were filling the second, some fuel
has already cross-fed from the first.
Then if you leave the aircraft
parked on a lateral slope, fuel willWhat Can We Learn
- Plan the descent
well in advance. - It is vitally important to
understand your fuel system. - When sideslipping, always
select the upper tank. So, for a
left sideslip use the right tank. - The fuel goes where the ball goes
- in the air and on the ground.
- Visually check the fuel no matter
how inconvenient this is. - Never trust an aircraft fuel gauge.
- With a small dihedral you are
more likely to have sloshing
and unporting problems. - Don’t expect a Cessna single
to give you the same amount
of time out of each tank. - If both tanks are low, it is better
to run one tank dry at altitude,
rather than have a nasty shock
in the circuit.
He opens
the throttle,
but nothing
happens,
so he throws
it in a ield.Aiming to make safer pilots of us, here veteran instructor Jim Davis looks at extracts
from oficial CAA Accident Reports from his homeland of South Africa and analyses
why things went wrong and how we may all avoid making similar mistakes.australianflying.com.au 79
July – August 2018 AUSTRALIAN FLYINGSurely, we were all taught, on
our very first f lying lesson, that
you should never believe aircraft
fuel gauges. Secondly, he didn’t
understand the simple principle
that the fuel goes where the ball
goes. If the ball is to the right,
then all the fuel–in all the tanks–
moves over to the right-hand
side of the tanks. So, if the fuel
is lowish, it can slosh away from
a tank ’s outlet pipe, and cause a
condition known as unporting.
This means that the outlet pipe
is sucking air–no fuel is getting
through to the engine–so it
will stop, which is exactly what
happened to this bloke.
This is so unnecessary –
it didn’t have to happen. It
endangered lives and put up all
our insurance premiums.
The pilot should have been aware
of possibility of unporting if he
didn’t keep the ball in the middle
when the tanks were low. Once
he started manoeuvring for the
landing his attention would have
been largely outside the cockpit and
not watching the ball. This is just as
it should be – but not when the fuel
is dangerously low.
Now we come to a part that I
find difficult to understand. The
report says that the pilot joined
right-hand base for Runway 11,
but it seems he must have been too
high, otherwise why use full f laps
at that stage?
Can a 2000-hour pilot reallycross-feed to the lower tank and
overf low. So if you leave a full
aircraft overnight on the grass,
it could easily have dumped an
hour’s fuel by the morning.
Cross-feeding in the air, due to
the ball being slightly out of the
middle, has two results. It can lead
to fuel overf lowing from one tank
and going out of the vent, so you
have no reliable way to manage
your fuel by timing. If you get say
three hours out of the left tank,
you could get only an hour-and-a-
half out of the right one.
Finally, on all high-wing
aircraft, pilots are inclined to skip
the all-important duty of visually
checking the quantities through
the filler cap. It’s just too damn
difficult to get up there and do the
job properly.
All these little problems
can quickly combine to give you
an engine stoppage when you
think you have a comfortable
BOB ADAMS hour to spare.