Would you fly this Aircraft?

I'd be interested in "go/no-go" opinions of others, based solely on the
following information ...

"Naturally aspirated, carburated, light twin (C172 engines) - hasn't been
flown for 3 weeks - at the conclusion of last flight was fueled to the max.
Has since been observed to have fuel dripping from the right-hand engine
nacelle. Has been checkd by engineer who has put it down to "full tanks +
volume change due to temperature changes".

No other information available.

My initial thought was "why wouldn't the excess fuel get forced out through
the tank vents, rather than through "something" within the engine bay.

How many of you would / would not fly this aircraft based on the above info?

(I appreciate that more info would be nice, but it's all I have available).

Many thanks,

Cheers,

Based on that, I would NOT fly the aircraft UNTIL I had
personally inspected it to see what was leaking and from
where. If the float valve was leaking, the fuel level would
rise and over-flow from the vent on the carb. That is an
easy fix. If a fuel line is leaking, it is also an easy
fix. If a crack is in the float bowl, you replace the carb,
also easy but more expensive.

What is the history of the airplane before and on the last
flight? Was is parked with the fuel valves OFF or ON?


--
James H. Macklin
ATP,CFI,A&P

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.


"C J Southern" wrote in message
...
| I'd be interested in "go/no-go" opinions of others, based
solely on the
| following information ...
|
| "Naturally aspirated, carburated, light twin (C172
engines) - hasn't been
| flown for 3 weeks - at the conclusion of last flight was
fueled to the max.
| Has since been observed to have fuel dripping from the
right-hand engine
| nacelle. Has been checkd by engineer who has put it down
to "full tanks +
| volume change due to temperature changes".
|
| No other information available.
|
| My initial thought was "why wouldn't the excess fuel get
forced out through
| the tank vents, rather than through "something" within the
engine bay.
|
| How many of you would / would not fly this aircraft based
on the above info?
|
| (I appreciate that more info would be nice, but it's all I
have available).
|
| Many thanks,
|
| Cheers,
|
|
|

"Jim Macklin" wrote in message
newso6Tf.118036$QW2.75471@dukeread08...

What is the history of the airplane before and on the last
flight? Was is parked with the fuel valves OFF or ON?

Several years ago the aircraft showed the same symptoms - on that occasion
the leak was due to a fractured primer line.

Prior to the last flight there were no know issues.

Aircraft is always parked with fuel selectors ON, but following the leak the
right hand fuel selector has been turned off to stop any more leakage.

Personal investigation would be difficult - it would require removal of the
cowling (which presumably the engineer has done). If the cowling isn't
removed, then the only place you can see anything is via the oil filler
flap - which lets one see very very little.

"C J Southern" wrote in message
...
I'd be interested in "go/no-go" opinions of others, based solely on the
following information ...

"Naturally aspirated, .......

Pointless question. Insufficient data for any kind of decision.
Presumably, you'd preflight the aircraft anyway, which obviates your above
question.

The crux of the question really is "if the licenced and qualified engineer -
who would get paid for fixing the problem if there was a problem - says that
it's OK, does one trust that?

Do you trust the FBO? Why or why not? Follow the money.

Part 2 of the question is "why would full tanks cause this - why wouldn't
the excess get squeezed out the tank vents"?

That by itself, and no explanation from the "licensed and qualified
engineer" as to what caused it, would cause me to let somebody else be
the guinea pig.

Jose
--
Nothing takes longer than a shortcut.
for Email, make the obvious change in the address.

"John Gaquin" wrote in message
...

Pointless question. Insufficient data for any kind of decision.
Presumably, you'd preflight the aircraft anyway, which obviates your above
question.

Not really. For me, the question is do I bother making the trip to the
airport, or do I wait for someone else to be the "canary in a cage". I've
also got a slightly nervous a passenger to consider - last thing I want is
an engine fire with a nervous passenger sitting right next to it.

The crux of the question really is "if the licenced and qualified engineer -
who would get paid for fixing the problem if there was a problem - says that
it's OK, does one trust that? As a pilot I won't be able to see where the
leak is coming from without removing the cowling - which is engineer only
territory.

Part 2 of the question is "why would full tanks cause this - why wouldn't
the excess get squeezed out the tank vents"?

Removal of the cowling is required and I would want to
either do it or be present. Fuel lines can leak due to
loose fittings, broken lines that crack from fatigue or
abrasion. I would want to visually inspect for any signs of
fuel stains and any damage.

The problem is not just possible engine failure, but fire
and explosion inside the wing or cowling.

Since mechanics {engineers} often won't fly in airplanes
they have performed maintenance upon, you, the PIC must be
able to inspect the airplane and satisfy yourself.


--
James H. Macklin
ATP,CFI,A&P

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.


"C J Southern" wrote in message
...
|
| "Jim Macklin" wrote
in message
| newso6Tf.118036$QW2.75471@dukeread08...
|
| What is the history of the airplane before and on the
last
| flight? Was is parked with the fuel valves OFF or ON?
|
| Several years ago the aircraft showed the same symptoms -
on that occasion
| the leak was due to a fractured primer line.
|
| Prior to the last flight there were no know issues.
|
| Aircraft is always parked with fuel selectors ON, but
following the leak the
| right hand fuel selector has been turned off to stop any
more leakage.
|
| Personal investigation would be difficult - it would
require removal of the
| cowling (which presumably the engineer has done). If the
cowling isn't
| removed, then the only place you can see anything is via
the oil filler
| flap - which lets one see very very little.
|
|
|

#2 Full tanks increase fuel pressure, a poor seal on the
carb float needle valve will leak and fill the bowl, which
then over-flows. The tanks have about 10-15% free space
even when full to allow parking on non-level surfaces before
the tank vents begin to drain.


--
James H. Macklin
ATP,CFI,A&P

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.


"C J Southern" wrote in message
...
|
| "John Gaquin" wrote in message
| ...
|
| Pointless question. Insufficient data for any kind of
decision.
| Presumably, you'd preflight the aircraft anyway, which
obviates your above
| question.
|
| Not really. For me, the question is do I bother making the
trip to the
| airport, or do I wait for someone else to be the "canary
in a cage". I've
| also got a slightly nervous a passenger to consider - last
thing I want is
| an engine fire with a nervous passenger sitting right next
to it.
|
| The crux of the question really is "if the licenced and
qualified engineer -
| who would get paid for fixing the problem if there was a
problem - says that
| it's OK, does one trust that? As a pilot I won't be able
to see where the
| leak is coming from without removing the cowling - which
is engineer only
| territory.
|
| Part 2 of the question is "why would full tanks cause
this - why wouldn't
| the excess get squeezed out the tank vents"?
|
|
|

Fuel has weight, a little less than .5 pounds per foot of
distance. A high wing Cessna has about 3-4 feet between the
fuel tank and the carb float. The float in the bowl is
raised by the liquid fuel in the bowl and by a lever,
presses the needle valve closed, stopping the flow of fuel
by gravity.

If the needle valve is leaking, there are two problems,
during engine operation, the fuel level will be too high
making the mixture too rich, although this can be manually
leaned, but the bowl may still fill to over-flow and this
will cause a lose of fuel which can result in an fuel
starvation accident.

When parked, it can cause a fire hazard and certainly waste
expensive fuel.

For a science experiment, take a straw and place it in a
glass of water and place your finger over the end of the
straw. When you lift the straw, the water won't flow out of
the straw because it isn't vented, but the pressure of the
water is due to the weight of the water caused by gravity.

Low wing airplanes and some high wing airplanes with carbs
also have fuel pumps, all fuel injected engines have pumps
because gravity is not powerful enough to operate the
injection system.


--
James H. Macklin
ATP,CFI,A&P

Just to explain this, ATP is Airline Transport Pilot
CFI, I have Gold Seal Airplane SMEL and Instrument
A&P Airframe and Powerplant mechanic



--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.


"Morgans" wrote in message
...
|
| "Jim Macklin" wrote
in message
| news:II7Tf.118045$QW2.26850@dukeread08...
| #2 Full tanks increase fuel pressure, a poor seal on
the
| carb float needle valve will leak and fill the bowl,
which
| then over-flows. The tanks have about 10-15% free space
| even when full to allow parking on non-level surfaces
before
| the tank vents begin to drain.
|
| Hold the phone, here.
|
| You mean fuel tanks can build up pressure with functioning
vent lines?
| Hummm.
|
| If it is a bad (plugged) vent, then I'm not going to fly
it until *that*
| detail is fixed.
| --
| Jim in NC
|

"John Gaquin" wrote

Pointless question. Insufficient data for any kind of decision.
Presumably, you'd preflight the aircraft anyway, which obviates your above
question.

Insufficient date, yes.

Do tell, what is preflighting the aircraft going to tell you, other than
there is fuel leaking from a "bad place (tm) and to get to the bottom of it,
some dissassembly will be required?

Sounds like a no go, to me.
--
Jim in NC