December 1982 - American Bonanza Society

COLVIN'S CORNER (Continued) ______ _
installed the newly-overh auled engine in
our 3 5, N4560V.
Now a second questi on: We also
operate a second Bonanza, SI N 0-911 ,
N3705N, formerty owned by Mr. Russelt
Rink . This, of course , has the original
firewall-mounted tank and radiator. On
this airplane we have a problem with
high oil temperature. We had planned
to Instalt on this airplane the later-type
oil radiator in hopes of lowering the oil
temperature. Do you think th at such a
change would accomplish the desired
result
Always enjoy your column.
Lewis C. Criley
ABS #3497
Dear Mr. Criley:
The radiator and oil tank were built
by Beech. It is not uncommon for one
or more tubes to leak: however, several
can be plugged without imparing
cooling capacity. The oil cooler and
lank were coated with slushing
compound at the time of manufacture to
protect the inner radiator tubes and
tank, so your best bet is to repair this
tank.
The tank from the E-225 series
engine could be used with FAA
approval, but it wou ld entail
considerable modification of the rear
engine baffle.
Now, for Bonanza SI N 0 -9 11 : there
is always the possibility that the oil
cooler needs to be cleaned. Soak it in
solvent and slosh the solvent good.
There is a possibility that the engine
sump pump is worn and is not returning
oil to the cooler at a rapid rate. There
is also the possibility that the pump is
not the high capacity. The high
capacity pump gears have eight teeth
per gear; the standard has six.
FUEL GAUGING SYSTEM
PROBLEMS
Oear Norm :
Our fuel gauges are acting up.
Sometimes they work - partially,
sometimes - not at all. I've searched
the Newsletter for an article on where
to start first. I suspect it is the sensing
element in the tanks, but I don't want to
pull them out if that's not the first place
to investigate. I've talked with several
A&Ps, but no one has a hint on how to
diagnose the problem. Are float units
available for older Bonanzas like my
J-Model Is there a way to test whether
or not that's the problem Someone
should have had this problem before
and developed an optimum procedure.
"m amazed the Newslett er has no
listing in the Index . Thi s is not a real
serious matter, as I can fly by time; but
I would like to get the system working If
it is not too expensive.
James D. Johnson
ABS #1731
Dear Mr. Johnson:
First, is the fuel gauge for both tanks
erratic Are the connections loose or
corroded Poor ground connections are
frequently the cause of erratic
operations. Remove the fuel caps and
physically lift the transmitter floats. If
the fu el gauge does not respond, hook
a meter to the transmitter and measure
the resistance. If the transmitters are
defective, they must be replaced by a
different brand; and thi s requires a kit
which requires some rewiring.
Next, check the bottom tank to see
that there are no wrinkles to interfere
with the float.
BRITIAIN TIP TANK
DRAINS/ FUEL FUMES IN
CABIN
Dear Norm:
I have an H-35 with Brittain tip tanks.
The dump drains need replacing, and
I cannot find them - even though they
were Beech approval. Can you help me
locate a pair Or, was there a Directive
saying they could be plugged due to
having a central drain
I have also been getting gas fumes
when in a left turn or using fu el from
the right wing. The selector has been
checked and no stains show under the
wing nor spills on the floor.
Walter C. Harbeck
ABS #1 3 152
Dear Mr. Harbeck:
Osborne Tank Company, Star Route,
Box 12, Oro Grande, California 92368,
is currently building the Brittain tank.
They are the most logical source of
parts.
There is no set pattern for gas fumes.
8 e sure the tank fuel vents are open
and that they point forward. It would be
well to look inside the fuel well,
especially where the main fuel line exits
the tank. There is a 90-degree fitting in
th e fu el tank vent line, located at the
forward end of the root rib. This fitting
is out of sight but is adjacent to the
wing fresh air duct. If this fitting is
seeping, you would get fumes in the
cabin. Unfortunately, the only way to
inspect it or fix it is to pull the wing. It
is not good to have fuel leaks; but
should it be this fitting, a slight seepage
would not be dangerous.
OPERATION OF 10-520-BA
BEYOND RECOMMENDED TBO
TIME
Dear Norm:
The engine in 7985M is still purring
- using approximately one quart of
AeroShell W-50 wt oil per six hours,
maintaining compression readings in
th e low-to-mid seventies on all cylinders
(a s checked during annual inspection
earli er this month) and is leak free as it
passes the 1 ,400 hour-since-new point.
My local Beech service people have
hinted that I should be thinking about
majoring the engine pretty soon. I have
been under th e impression that the
TBO on the IO-520-BA Teledyne
Continental Engine is now 1,700 hours
- having been raised from 1,500
hours by the manufacturer last year.
With th e awareness that these are
" recommended " times and not
intended to be taken as absolute, I
persist in the view that this engine will
require majoring when it begins to
display the symptoms that warrant the
turn around: excessive oil consumption,
rough running, leaks, etc . Of course, if
the bloody thing decides to cease
performing suddenly - without being
considerate enough to exhibit
symptoms, then I guess the laugh and
the dead sti ck landing will be on me.
Foolishness aside, I would like to
hear some sincere comments and
remarks relating to engine turn around
time and also the names of some
reputable rebuild shops.
G. B. Ross
ABS #12144
Dear Mr. Ross:
In this case, Continental Motors has
recommended that their engines be
overhauled at 1,700 hours. This is a
conservative figure, based on the
experience of inspecting a number of
run-out engines. I'm sure experience
has shown that at 1,700 hours the bulk
of the engine components show a
minimum of wear, which means that in
most cases the engine could be run
longer. However, it must be
remembered that fuel pumps, oil pumps,
generators and vacuum pumps also
run beyond the recommended TBO.
Once an engine is run beyond TBO,
parts wear accelerates; so it may
require more part replacements when it
is overhauled.
Where the engine is flown makes a
difference; so there are lots of variables.
If you should elect to go beyond
1,700 hours TBO, it would be wise to
use oil analysis which would forewarn
of upcoming wear or part failure.
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american bonanza society