Date: Tue, 18 Nov 1997 01:12:09 -0800
From: Johnny <email@example.com>
Subject: Fuel System Design and Management 101 [very long](was: Denver Crash,
Craig P Earls wrote:
> Scott Derrick <firstname.lastname@example.org> writes:
> > there was one key statement that indicated the cause of the crash.
> > **He was between 300 and 500 ft agl. **
> > Traveling at 200mph, you don't fool around with fuel switches or
> > mirrors at that altitude, unless you have a death wish.
> > I'd call the cause stupidity if Denver was actually reaching over his
> > shoulder with a pair of vice grips to change the fuel selector at 300
> > agl.
> Now, that is the voice of reason.
I thought I might just post a little bit of common sense about fuel
systems just as a reminder to those of us who haven't killed ourselves
yet in a fuel system related crash.
The following will be boring and mundane, but apparently there is some
need for it.
# Fuel System Design and Management 101
To review some of the basics about deleivering fuel to the powerplant of
a powered aircraft.
Grade point required to pass the class:
Must still be living after your most recent flight. And no, the class
will not be graded on a curve.
It seems that more fatal crashes of GA , or "sport", aircraft are
attributable to mismanagement of the fuel system, than any other
singular cause. As rational and responsible pilots we have to pause for
a second and wonder why the hell that is. We are trained in fuel system
management. We practice fuel system management every time we fly. We do
the same when we drive a car, mow the lawn, or even take the kid out
with the go-kart. Why is it that when we fly we have so much trouble
managing our fuel systems?
Is it that the fuel system itself has problems that we can't overcome?
Sometimes. In the case of a plugged vent or a calapsed or piched line,
or a faulty valve, or a stuck float, or bad pump, that might be the
case. If that is so, how do we design around those possible incidents
and what can we do in maintaining our aircraft to avoid these things?
Maybe the Human is the faulty part of the system. It is the one key part
that if it fails, the question of all the other parts working or not
becomes a non-issue. We must remember that the goal is to provide the
engine with fuel, on more a less a non-stop basis. That doesn't just
mean getting the fuel from the aircraft's fuel tank to the engine. It
ultimately means getting the fuel from the fuel truck at the airfield,
to the engine. The best fuel system in the world and the most alert
pilot doesn't mean dick if all the fuel is still sitting on the ground 2
hours into a 3 hour flight over water, rough terain, or conjested areas.
I could just write "common sense" in here and leave it at that, but
apparently that isn't enough. So let's explore for a minute some of the
possible solutions to the fuel system management crisis.
First, how can we design and build a more foolproof fuel system?
Starting with the beginning (the filler cap) and working to the end (the
cylinders on the engine), one might want to look at the following
questions and see if they can answer "no" to any of them.
1. Does the tank filler cap have a secure locking mechanism, cover door,
or other means to keep it firmly attached at all possible flight
2. Is the filler neck grounded to the airframe on a metal aircraft, or
is there a means for attaching the ground clamp from the pump to a spot
other than right there where the fumes are, on a non-metal aircraft?
(compost builders will have to fight this one out amongst themselves)
3. Is the vent on the fuel tank of sufficient size and correctly located
to allow fuel to flow at a positive pressure from the tank under all
applicable flight conditions... even including icing conditions if you
are exposing yourself to them?
4. Do you have a means for draining any possible water contamination
from the tanks, and are the drain valves correct for the application and
located at the lowest point in the tank when the aircraft is sitting at
rest on the ground?
5. Are there finger strainers on the fuel pickups inside of the tanks,
and are they of sufficient size to flow fuel under the most demanding
engine requirements even when they might have a partial blockage?
6. Are the fuel pickups at the next lowest point in the tank after
taking into consideration a sump level for the water drains? (there must
be a small volume between the drain point and the pickup point... an
unusable volume for water to collect and reside)
7. Are the fuel pickups at that low point when in level flight?
8. Are they still the at the low point when in a climbing attitude?
9. If not, is there an alternative pickup, second sump, header tank
arrangement, placard, or some other means to either supply fuel to the
engine in a low fuel climb out situation, or a means to help prevent
operation under those conditions? (this is the "low fuel go-around"
10. In attaching the fuel lines to the tanks and everywhere else they
go, is there a securing device to make sure the lines don't fall off,
like a hose clamp, AN fitting, etc? (don't laugh... it's happened, more
11. If they are AN flare fittings, did you use "anti-tamper" paint to
12. Have you actually looked at the condition of the lines lately to
check for cracks, kinks, chafing, fraying, splits, holes, or just plain
13. If the lines pass through any bulkheads or other airframe members,
did you use bulkhead fittings?
14. If not, did you use at least use a rubber insulator of some sort?
15. Are the lines clamped down in often enough intervals to keep them
from looking like a guitar string in motion when the engine is running?
16. Are they free from stress from one clamp to the next?
17. Are the clamps insulated, like an Adel?
18. You did use either aluminum, stainless, or MIL-H-6000 lines, right?
19. Do you have a fuel shut-off valve?
20. Is it marked correctly to plainly show tank selection and/or the
21. Is the knob or handle the correct color? (I like white, some like
22. Does the valve have a detent system or lockout device to "tell" your
hand what's going on?
23. Does it move freely enough so that you can actually feel the detent
system that it might have and can you tell where you are without
24. If the system uses a primer plunger, is there a means for locking it
into the "closed" position?
25. Can you slide and turn the plunger freely enough to actually know
without looking when it is in and locked?
26. If there is a fuel pump or pumps in the system, can the fuel still
get from the tank to the engine if the pump fails?
27. If the fuel tank is below the engine, is there more than one fuel
28. Are the pump(s) of the bypass type? (this means, do they still allow
fuel to flow through them when they are shut off? something to know
about when trying to use automotive electric pumps)
29. Is there a fuel filter in the system?
30. Can fuel still get from the tank to the engine if the filter gets
31. Is there a convenient way to inspect the condition of the filter,
either visually or by taking it apart and looking inside?
32. Is there one lowest point in the whole system which has an
"unusable" volume for the collection and removal of water and other
contaminants? (could be a gascolator, sump, water-trap, etc)
33. Does that lowest point have a convenient means of draining the water
[34-36 apply to carburetor engines]
34. Is there a means of draining the float bowl?
35. Is the material of the float chemically compatible with the fuel you
36. Is there a means for heating the air intake to prevent icing of the
37. Is the throttle self opening in the event of a throttle cable or
38. Is there an air filter for the intake air?
39. Is there a way to bypass that filter if needed?
[40-46 apply to the system as a whole]
40. Is the system leakless?
41. Did you pull the line off of the carburetor, fuel spider, fuel rail,
etc. to test and measure the amount of fuel that is being delivered by
42. Did you perform this test with the aircraft in many different
attitudes on the ground? (ramps, jacks, trailer bed, truck, whatever it
takes to tilt the aircraft severly and see if you still get the amount
of fuel you need at the outlet of the system)
43. Did you do these tests with varying amounts of fuel in the tanks?
44. While doing these tests, did the fuel system continuously deliver
fuel at a rate that was many more times that than the engine will
actually ever need?
45. Did you do similar tests with the engine actually running? (be
careful here, this can get a little tricky. secure the aircraft well,
and make sure everyone is well clear)
46. Are you comfortable with the design and construction of the fuel
I'm sure there are many many many more things that can be added to this
list. This is just off the top of my head. Feel free to expand this to
take into consideration some of the more unusual situations out there.
Other things to look out for are:
Loops and high spots in a gravity feed system. Places where an air
bubble might cause a "vapor lock" or a siphon action to stop. On a high
tank gravity system, you want it to be downhill all the way. It's not
supposed to be a siphon. If this is unavoidable, then you will have to
have a pump either at the top, or at the bottom, and if it is electric,
then you will have to have another mechanical one on the engine. Now you
have what is more like a low tank system.
Watch out for low spots that have no drains. Make an intentional low
spot and put a drain there.
Never, Never, Never, have a tank pickup without a finger strainer. Those
stories about the dead mouse and the golf ball and the ping-pong ball
are all true. Make sure there is nothing in the tank when you are
closing it up or done working on it. That story about the shop rag is
Now, let's look at what we can do about the biggest fault in the
system... the Human element.
Again, see if you can answer no to any of these:
1. Did you really ground the aircraft before filling with fuel?
2. Is there a placard in the area of the filler that indicates what the
correct fuel is for the aircraft?
3. Do you know what the different fuels are, and what you can safely
substitute for the "correct" fuel in the event of non-availability?
4. You are responsible for knowing what you actually did put in the
tank. Did you smell it, taste it, look at it, feel it, or what ever you
need to do to actually, positively, absolutely, know beyond a shadow of
a doubt that what you just filled up with was really gasoline... before
you filled up with it?
5. Is there a chain, string, cord, wire, flag, placard, buzzer, light,
horn, or some other mechanism that will prevent you from leaving the gas
cap off after you are done filling the tanks?
6. Do you know where and how to drain all the drains and how to check
for water and other contaminants?
7. Is doing all this part of your preflight checklist... you know, the
written one, not the one in your head?
8. When you get in the cockpit and are seated for flight, can you read
the fuel selector valve?
9. More importantly, can you feel it?
10. Before you start the engine(s), did you check what the fuel gauges
or site tubes said and compare that to what you know is actually in the
11. Can you trust your fuel gauges? (that's a trick question)
12. When you are doing your run-up, did you try selecting all of the
fuel tanks individually, waiting for a while on each one, and monitoring
the fuel pressure guage to make sure that you can actually get fuel from
all of them to the engine, BEFORE you try and take-off?
13. Did you do all this with the boost pump off?
14. Are all of these things on your pre-takeoff checklist... you know,
the written one, not the one in your head?
15. You did use the checklist, right?
16. Before you depart, have you planned your flight enough to know how
much fuel you will need to get to your destination?
17. So, if your final destination is farther then you can go on the fuel
you have, then your real destination for this flight is to where you can
get more fuel, right?
18. Have you confirmed that there is actually fuel where you think there
is? (how many of us have gotten somewhere that was supposed to have fuel
only to find everything closed up for the day and the next fuel too far
to go, on what's left in the tank... ain't that a bitch? how many tried
to make it to the next fuel anyway? how many won't try that again? ;)
19. Have you planned an alternate fuelling destination just in case you
can't get through weather, or everyone is gone, or they are just simply
out of fuel there that day? (for all you easterners, this can be a real
situation out here in the west where the next dot on the chart can be
more than 100 miles away)
20. Now that you have finally departed, have you devised some sort of
system for monitoring and managing your fuel consumption?
21. Is it a timer, a buzzer, a fuel flow device, part of your GPS, your
22. Can you still do it correctly without any of those things to help
23. Is it part of your in-flight checklist... you know, the written one,
not the one in your head? (is there an echo in here?)
24. A lot of pilots put the checklist away once they are up to cruising
altitude, that's not you is it? (watch out for the negative in the
[25-27 are essay questions]
25. On many aircraft with multiple tanks, and a selector that will only
select one tank at a time (like my AA-1), it is proper proceedure to
switch tanks every so many minutes during the flight. When you get low
on fuel, is it also proper proceedure to run one completely dry so that
you know that you have nothing left there and what you see on the
remaining tank is what you got?
26. On aircraft with aux fuel systems that allow feeding directly from
the aux fuel tanks, is it best to run those aux tanks dry before
switching to main tanks?
27. On aircraft with aux fuel systems that are of the pump transfer
type, is it best to transfer from the aux to the main only after you
have almost exhausted the mains?
28. When you see that you are not getting the milage that you expected
to get (high head winds, whatever) do you start looking for a closer
refueling destination than you originally planned... BEFORE YOU ARE FUEL
29. When you ARE fuel critical, and you can't find a place on the chart
to land and can't see the ground because you are "vfr trapped on top",
and your GPS is not working, and all you have is a radio, do you call in
right away and confess to the person on the other end as to what a
dumbshit you have been and start promising anything to get some help
down through the clouds to a place that might have a survivable landing
Again, there are many more that can be added to this little self help
quiz. The main thing is to be VERY familiar with your fuel system and
how it works and where everything is, by feel. Know exactly how much
fuel you have at any given point in the flight and be able to closely
estimate your remaining endurance and how far that will take you. Don't
try to stretch. If you do burn yourself, know how to manage your power
to increase your endurance and range if you have to. But mostly, plan,
plan, plan and USE THE CHECKLIST.
I know guys that have many many many thousand more hours in the seat
than I have, and most of them still drag out that silly, tattered, "been
re-laminated 20 times", checklist. And they actually put there thumb on
there and go down the list, before, during, and after the flight.
Obviously, this behaviour is more common on the more complex types, but
that doesn't mean that it is any less important on the simplest types.
Any type with an engine is a type that needs fuel to do what it is
intended to do, or at least what it is expected to do. It's way less
skin off your ass to use the checklist, than to screw up because you
Now, to reward all of those that stuck through all of this tedious
review, here is the first in a small series of corny but true tales
about a low timer that got lucky... not once, not twice, but three
Once upon a time, there was a low time pilot that had just got his first
non-cessna checkout. It was a Cherokee 140 it was, and boy, did it fly
way nicer than those stupid C-150's he'd been flyin'. ;-P
He had flown the Cherokoee just enough hours to not be scared of it
anymore, and was ready to impress a lovely young female with his
pilotage and high-rolling "see, I can even rent a Cherokee" lifestyle.
After a lovely lunch flight together and an extended tour of the
islands, with many touch and go's included, it was time to get the girl,
and the plane, back to where they each came from.
The Cherokee has a fuel selector that is off-right-left. The Cessna's he
was so used to just always were set to "both", and didn't really require
much attention. Even though he was aware of his new fuel management
duties involving the Cherokee, and had "selected" his way through a few
flights in it before, he hadn't flown the plane enough for it to become
second nature, and was too busy being impressive to be draggin out a
cruddy ole checklist while in the presence of female company... uh, very
close presence that is.
While making a perfect pattern and one of his better landings of all
time at her home field for everyone to see, he had completely forgotten
about the fuel selector and was running on the left tank which was just
about exhausted of the precious fuel. To make matters worse, after
landing there was quite a fairwell that took place at the terminal,
between the girl and himself, and by the time he finally got back to the
plane to go home, he was, well, in lust, to say the least.
Trying to shake it off, but in a hurry to get the rental back home now
that it had served it's purpose, the beater that it was, and the fact
that it was now pretty much dark and there were no lights at his home
field, he again ignored the fuel selector, and the checklist which was
now lost and gone forever. This meant that he was about to takeoff still
selected to the left tank that probably had less than a gallon usable in
it, to depart with a left hand turn out. If he had done at least a half
ass run-up before try to depart, the thing would have probably run outta
gas right there on the ground. It wasn't to be however, as he hurried to
the end of the runway to start his doomed takeoff roll.
With only himself aboard and something less than 10 gallons fuel total,
he thought to himself "man, this thing is really running good today" and
he slammed it into a steep left climbing turn as he cleared 500 agl
taking off out over Puget Sound. It was then that, yes, the engine quit
making power extremely suddenly.
Immediately, all of his training came into play. First thing, fly the
damn airplane... whew, yep still flying... confirm fuel to the
engine...pump...fuel selector...mixture...gauges... FUEL SELECTOR!!!
Right guage, Right tank, ok, the boost pump is stil on... why is the
engine still not running??? As the lights on the shore and their
reflection on the cold water drew closer and closer, it was becoming
obvious that there was no way he was going to make the little patch of
grass he had mapped out and was flying towards. It was time to ditch it
near the shore and see what 40 degree water felt like that night.
Mags... radio...hell, no time for the radio... rechecking fuel, yep,
it's all on... then all of a sudden, that sweet mother of all inventions
burped back to life and just in time to regain a positive rate of climb
while skimming along the shoreline escaping his probable watery grave.
"Man, was that close", he thought.
Time from 500 agl in a steep turn at slightly over Vy, to a recovered
glide just a few feet from impact was much less than a minute, but I'm
sure it seemed more like an hour to the poor guy.
On the 15 minute hop from there back to home base he had a small amount
of time to reflect on where he had gone wrong. Oh, there were several
mistakes along the way, but lack of planning, failure to use the
checklist on an airplane he was not familiar with, and severe
distraction (and I heard she was QUITE a distraction, to say the least)
were among the biggest boo-boo's on the list.
-j- (other 2 tales of fuel mismanagement to come later...)
Date: Tue, 18 Nov 1997 15:53:06 -0800
From: Johnny <email@example.com>
Subject: Re: Fuel System Design and Management 101 [very long](was: Denver
Crash, Design Flaw)
Kenny Danielson wrote:
> Great post, Johnny.
> Now, a question: Is there any technical reason to take-off with the Cessna
> selector on "BOTH" rather than on "RIGHT" or "LEFT" ??? It seems to me that
> experiencing an engine problem with the selector on one tank, all the pilot
> need do is switch to the other tank to be assured he had done all that is
> possible with that part of the system. Note, I asked about a technical
I was thinking C-170 or -172 or something when I wrote that, but
actually refering to the C-150 which I think is just "on-off". So, it's
really "both" no matter what on that airplane. It's the bigger Cessna's
that have the "both" position on the selector. It's been a while since I
flew a Cessna, so I am having trouble remembering which is which.
My hangar friend dumped his C-170 into Martha Lake not too long ago, and
the feds said it was a case of vapor lock. He had his selector set to
"Both" and had about 15 gallons on board to make the 10 minute flight
back to WA38. When he banked left after take-off, the engine quit and
didn't restart. They went swimming.
After hauling the plane out and getting it back to WA38, they cleaned up
the engine and drained the fuel tanks, put new gas in, and the engine
fired right up and ran flawlessly. The pilot thinks that perhaps his
left turn maybe wasn't as coordinated as it should have been, and that
maybe one of the fuel pickups pulled some air, which then evacuated the
line because the selector was set to "both", which in turn killed the
engine, and the fuel system didn't have time to recover with more gas in
the line before they hit the water.
Someone else was muttering something about the C-170 having a placard
about not setting the selector to "both" with less than a certain amount
of total fuel aboard, but I don't know enough about that plane to
comment on that.
It does seem that if you had two high tanks on a gravity system, and a
selector that had a "both" setting, that if you did suck air on one of
the tanks it could play hell with getting fuel to the engine after that.
In revamping my BD-4, which is a design that is notorious for having
"unique fuel delivery issues" because it has no dihedral and no sumps, I
opted for no conventional fuel selector valve. Instead, I just use
individual valves right at the wing root because I am also using an
"always full" header tank behind the back seat and then I pump from that
through another "on-off" valve between the header and the engine. Having
EFI, I have to pump anyway, so I figured that wasn't a big deal, and the
header tank allows me to have momentary losses in delivery from the wing
tanks without there being a problem. The header tank is vented back up
at the level of the wing tank vents, so it is always full. The header
tank is 5 gallons and I am putting a low fuel sensor in it that lights
an indicator on the panel if the level drops below 4 gallons or so. That
way I have a little advance warning of a potential delivery problem from
the wing tanks, before it becomes more serious.
I went to a huge pickup and line size from the wing tanks to the header
tank, so I am using the "kitchen sink drain" method for the fuel to run
down to the header tank. There are no loops so fuel can actually run
down past air that is on it's way back up if it gets some air in there,
and it will when you get down to less than a quater full on the wing
tanks... that's just how the BD-4 works. I also have 2 separate pickups
in the wing tank. One at the low spot when in cruise, and one at the low
spot when in climb. They just "T" together at the shutoff valve, which
is lower then both of them at any given flight attitude, except inverted
of course. The theory is that no matter which way you are uncoordinated
or turbulance or whatever, one of the wing tanks will have some fuel
running down it's line to keep the header tank filled. This is about the
only thing I could think up for a hershy bar wing with no dihedral and
not willing to add an ugly sump to the bottom of the wing.
That's not true. First I came up with all sorts of exotic "one-way"
baffling for the inside of the tank, and then there was the "false
bottom with an angle to it" idea, followed by the pressurized bladder
method, and a few others. The header tank was decided on as the cheap
and dirty way out of the problem, and I needed a little ballast back
there anyway. In an emergency situation, I can still use the 5 gallons
that it contains, and it gives me my "lowest drain point", especially
with the tail sitting on the ground.
As a side note, the BD-4, which is a great, cheap, tough, ugly, fast,
little 4 place, can probably attribute more of it's accidents to fuel
starvation than any other singular cause. That's fuel starvation with
quite a few gallons still left in at least one of the tanks. The old
"2-into-1" gravity system, like found on the C-150 just doesn't cut it
on that airplane.
Date: Wed, 19 Nov 1997 01:31:02 -0800
From: Johnny <firstname.lastname@example.org>
Subject: Adventures of the Low Time Pilot (2 of 3)
As you might recall, we last left our low time pilot friend just after
he had almost crashed his rented Cherokee into Puget Sound after gross
mismanagement of his fuel system...
Subsequent flights in that same Cherokee were made with due caution and
attention payed to managing the fuel system with the "Off-Left-Right"
fuel selector valve, and the appropriate fuel guages. It didn't take
long though for our hero to find new and more effective ways to live the
risky life that all pilots seem destined to pursue. Soon, he found
himself tiring of the flight characteristics that the rental Cherokee
had to offer, and went looking for a plane he could call his own.
After counting up all his pennies, while looking desperately through the
Trade-a-Plane for something he could afford, it became very clear that
his purchase choices were going to be slim. The biggest bang for the
buck seemed to be found in the Grumman column. After test driving many
different types of nice airplanes that he could never afford, he ended
up with a pumpkin orange AA-1 for a modest price.
How proud he was, and he just couldn't wait to take her up and get to
know all of her little secrets. But first he needed a good checkout. It
took a little while to find an instructor that had Grumman experience
that was also willing to help a 100hr pilot transition into what some
people refer to as "the small orange coffin". One brave soul stepped up
to the challange, and it wasn't more than a couple days later that our
low timer, and his master, were out joy riding the beans out of that
marvelous little airplane.
The check out was easy. The airplane flew the way an airplane is
supposed to and all the stuff in the cockpit was laid out almost exactly
like the C-150 that he had trained in, with the exception of 3 small
items... the fuel selector valve, boost pump switch, and the fuel
gauges. After already burning himself with the Cherokee fuel system, the
low time pilot wanted no more of that kind of trouble and listened very
intently as the master explained how to manage the fuel system which
included the same style "Off-Left-Right" selector valve as the Cherokee
had, and a boost pump, and something new... Site Tubes for fuel guages,
located on each side of the cockpit.
The low time pilot didn't seem to have any trouble with this. He was
very aware of the selector valve now, and knew about switching from one
tank to the other every so often to keep a little weight sensitive ship
like this balanced in flight. He liked the idea of the site tubes,
thinking they were more honest than an electric guage bouncing around.
They were easy to see, and one thing for sure, if you didn't see any
fuel in the tube, you could pretty much count on the fact that you
didn't have any fuel in that tank. "What could be any simpler?", he
After dazzleing the master with great feats of natural piloting skill
and talent, the master signed off the checkout flight and the newbie
dropped him back off at the airfield where they had started. Realizing
that he was in love with the the new airplane, and wanting to take her
up all by himself now that he was officially a "Yankee Pilot", he taxied
over to the pumps and filled her up.
That first AA-1 solo flight pretty much set the pace for many more to
follow with good by-the-book and by-the-numbers proceedures, or so it
seemd. But those first flights were just local hops and to practice all
of the basic manuvers over again to get the feel of the new ship and
find the "corners of the envelope". While the new yankee pilot was using
the fuel selector valve and boost pump the way he was supposed to, there
was something going seriously wrong with the proceedures in the cockpit.
The other airplanes he had flown all had regular fuel gauges on the
panel, while the AA-1 had those glorious site tubes to indicate fuel
level on the sides of the cockpit. They were easy to see, and easy to
read, but they were not on the panel. With all of the first flights
being local, and starting out with full fuel, fuel level and tank
selection had not been an issue in those first habit forming flights in
this new type, and somehow looking at the site tubes had not become part
of the regular scanning of the panel process. They were basically being
ignored except for at the beginning and end of each flight and maybe one
time in between while switching tanks.
Almost 90 days had gone by since his last night flight in the Cherokee,
so he thought he had better get that taken care of and take the little
AA-1 out for his first "under the stars" cruise in it. Being summer time
and school was out, he took his little girl with him to enjoy the clear,
warm, night flying conditions.
They had a ball that night, flying all over the place. They had eaten at
least $200 dollars worth of $100 hamburgers, the plane was performing
very well, and they had laughed hard from making gross sounds into the
intercom's clearance recorder and then playing it back over and over
again. Life was good.
The little one was starting to yawn though, and it was time to head back
to home base, which at the time was a well lit runway of about a mile in
length. Just perfect for doing those after dark takeoffs and landings to
keep night current.
The first landing was set up off of a long straight-in final. On the way
down, our loyal checklist using low time newbie went down the pre
landing checklist for that very simple airplane. ...boost pump
on...check, fuel selector to fullest tank... "hmmm, I can't see the site
tube over on her side of the airplane that well, because the light bulb
in there isn't that bright and she is slumped over a bit sleeping", he
murmered. "The site tube on my side, the tank we are running on, looks
about empty". "Good thing I used the checklist and caught that", he
shuttered to himself, as he switched to the other tank, the one that he
couldn't see the site tube very well for, but it looked like it had more
than the other one, so it was indeed the fullest... check. This was the
first mistake... misinterpreting the site tube. Yes, the tank he
switched to was probably the fullest, but not for long.
The runway is wider than what he was used to, and being a night landing,
it looked closer then it really was as well. Damn thing swallowed them
up and he thought for a second that someone had pulled the ground out
from under them. BANG! "Oh well, that wasn't my best landing for sure".
"Better do a few more patterns to get the hang of the way it looks while
landing at night in the new ship", he thought.
Around and around they went. He was required to do three takeoffs and
three landings to a full stop, but he wanted to get that perfect greaser
to end the night on. It took several more trips around the pattern to
really feel comfortable with the wide runway at night and the new plane.
All the time, boost pump on, mixture rich, throttle full, just like the
Being a perfectionist of sorts, and deverting more and more attention to
the perfect night pattern and landing certainly didn't help him to
remember to include the site tubes in his panel scan. Being barely lit
and out of the way, it was truly "out of site, out of mind". Not
esablishing proper scan habits that included looking down at the fuel
site tubes regularly, was about to take it's toll.
He finally got that perfect "squeaker with full stall" that he was
looking for, and thought he would go around just one more time to see if
he could repeat it. Big mistake here. NEVER say "just one more time"
when refering to flying. Climbing out, he got to 500 agl and made the
left turn to crosswind, and then it happend. It was very quiet all of a
sudden, and here we are again in a pretty good bank, less than 500 feet
off the ground, in pitch darkness but this time in a plane that likes to
glide best at about 90 mph.
He immediately knew what he had failed to do, and grabbed the fuel
selector without looking, and switched it to the other tank. Boost pump
was already on and mixture was already rich, and the engine came back to
life almost immediately, but the whole incident had still taken enough
time for them to sink 200 feet into to the black abiss below.
After getting a positive rate of climb going again, and his wits
restored, and the plane pointed in the right direction on downwind now,
he looked closer at the site tubes to see what he really had left for
fuel. The one on his left had the same small amount in there that it had
when he swtiched away from that tank on that first approach to landing.
The one on his right, which was no longer partially obscured by the
sleeping child because she had been awakend by the stark change to quiet
a few moments earlier, still looked like it had more fuel in it. He
brought the plane in, landed and taxied to the hangar. While sitting in
front of the hangar with the engine still running, he bent down and took
a really close look at that right side site tube. It was then that he
realized that what looked like fuel, was just a distortion in the tube
caused by the way the light bulb was positioned, and some scratches in
the glass. At night, once it was at or below 1/4 tank, it ALWAYS looked
like it had a 1/4 tank. Oooops.
During the drive home that followed, the little girl inquired "why did
it get quite all of sudden and feel like we went down?" Not wanting her
to be as scared as he was, the father replied, "Oh, just testing out
that boost pump to see how fast it gets the fuel to the engine." "Was it
fast?" the little girl probed. "Oh yes", replied the father. "It only
took about 200 feet to get it going again."
That night our newbie low-time pilot took several large leeps towards
shedding the newbie part of that title. He never again had a problem
monitoring his fuel system, not in any airplane, and has developed
several "little rules" that he applies to panel scanning and systems
awareness. He also replaced the site tube that had the optical illusion
and replaced and repositioned the lightbulb for it to prevent a repeat
of the misreading that initially lead him to beleive that he had more
fuel than he really did. But most importantly, the harsh reality of the
consequences that result from not knowing exactly how much fuel you
have, and where you have it, at all times, was driven deep into the the
low time pilot's proceedural cortex.
With all of that learning going on, how could he possibly have a fuel
management problem again??? Stay tuned for the final installment of the
Adventures of the Low Time Pilot.
From: Johnny <email@example.com>
Subject: Adventures of the Low Time Pilot (3 of 3 - the final saga)
Date: 21 Nov 1997
By popular demand, we again drop in on the now famous, low time pilot.
The last time we saw him, he had just evaded yet another crash into the
darkness due to a lack of fuel system awareness. Some time has passed
and he has been flying his AA-1 most vigorously, racking up over 100 hrs
in it in just six months. Having about 200 hrs total time now, with over
half of it in this airplane, he has entered the "invicible stage" in his
piloting career. That's the one where he is competant enough to fly
himself into many a situation that he doesn't have the wisdom or
experience yet to fly himself back out of. The following is a brief
accounting of one of those situations.
On a Sunday flight out to the ocean beaches, "Low Time" and his trusty
co-pilot "Half Pint", find themselves enjoying an unseasonably warm and
sunny day in the middle of what would normally be a wet and dreary
Pacific Northwest winter. They had departed with less than full fuel,
and the plan was to fill up on the way back from the coast, in Astoria.
Though they had never actually refueled in Astoria before, they had
landed there a few times, and found it to be a large multi-strip
airport, which seemd to have plenty of facilities. During the pre-flight
planning process, the "little black book" showed it to indeed have all
sorts of fuel available, so it was included in the flight plan. The
other small strips along the coast in that area didn't have any fuel,
hence the careful planning regarding a return refueling stop.
All of the usual ground antics involving these two flyers took place
that day, including the flying of kites at Seaside, a trip to the salt
water taffy store, a visit to the future site of a home for a famous
whale, some carousel rides, and much to much candy and ice-cream. As
with all good things, the day was coming to an end and Low Time wanted
to get back before he had to navigate the hills between the coast and
the inland metropolitan area, in the dark.
They piled into their trusty Yankee steed, and after letting out their
seatbelts out a bit to get them buckled, they were ready to roll. After
departing, it was just a 5 minute hop to the Astoria fuel pump. One of
those deals where you takeoff, make a jog or two, and then get lined up
for a straight in to the next runway. The sun was on it's way down, and
he was glad they had left when they did as it looked like a few clouds
were starting to appear behind them. They made the landing, and headed
over to what appeared to be the only gas pumps on the field.
The place was a ghost town. Not a soul in site on the whole field.
Nothing nowhere. As they neared the pumps, it became obvious that the
place was closed and their hopes of refueling had been dashed. Shutting
off the engine and coasting up to the locked pumps, Low Time pulled out
the airport guide and the chart and started looking for another place to
get some gas, while Half Pint started asking questions.
"Are they closed", she asked? "Looks like it", he replied. "But where
are we going to get gas?" "Not sure yet." "Do we have enough to get back
home?" "Nope, we're already pretty low and almost into our 30 minute
reserve." "Do we have to stay here tonight?" "I have school in the
morning you know" she said, already sounding like somebody's mother,
even at the age of 6. Pondering the thought of staying in Astoria for
the night, Low Time looked around a little and things were starting to
look pretty grim. With weather closing in behind them, darkness on the
way, and obligation of school in the morning, the first twinges of "get
home itis" were starting to set in.
The closest "real" airport on the chart was Hoquium. It was directly to
the north and although they would be landing without the required 30
minutes of reserve fuel on board, they would be able to make it OK, and
skies were clear in that direction. If they did go that way though, and
there was no fuel there either, they would have shot their only chance,
and would have to stay there for the night for sure, because there is
just nothing else around there. Thoughts of trying to find a place to
stay for the night in Hoquium were pretty dismal, and just about as grim
as staying right where they were, in Astoria. Besides that, they wanted
to go to the east to get back home.
What did lie to the east? Some hills to get over, and a bunch of little
airstrips that also have no fuel, or at least no fuel on a Sunday
evening. There was Elma. "We could make that", he thought. But then
visions of that little run down airport with a stinky but good little
cafe, and a fuel pump that usually had a sign that said "out of service"
hanging on it came to mind, and crushed his hopes of getting anything
there, except a cold while sleeping in the plane. He started to look
around in the plane to see what the blanket situation was like, and it
was grim as well. It was going to get plenty cold that night, and since
they had planned to be back before dark, they hadn't really come
prepared for camping out in the airplane.
[they should have just parked it at this point, and called for a cab,
gone to whatever hotel there was - even with cockroaches - and spent the
night there on Mr. Visa]
What else was to the east? Well, way out there, and pretty close to the
flight path we would take to get home anyway, there is always Olympia. A
pretty good size "real" airport that even has a tower, and two different
FBO's with fuel, with at least one of those being open late enough to
have refueled in the dark there before. "Can we make it", he thought?
Getting out the straight edge, the POH, and the calculator, he went to
work trying to calculate their probable demise.
"Let's see." "To take the straight line we gotta climb pretty good
initially to get over the first set of hills." "Then we can hold that
altitude all the way to here, at which point we can make a 500 fpm
decent to here, and from there get lined up for a glide to a landing if
we had to". Does it sound like it would be too close? Why chance it?
What was it that was so bad about staying there for the night? So what
about the little one missing a day of school. And why would anyone want
to risk not only their own life, but their whole family's life as well?
Is "get home itis" that powerful? He had read about "get home itis"
before in the various flying magazines and been warned by his primary
instructor about it, but he always thought "how absurd, that would never
happen to me".
The other factor working here was the fact that he really thought they
could make it to the destination airport. He had calculated it very
carefully, and confirmed the calculations with a "does this seem right"
angle, based on quite a bit of recent flying experience in this same
airplane. He knew the airplane pretty well, and had used it mostly for
cross country flights of full tank leg distances, and he knew pretty
much exactly what it would take to make the hop to Olympia. The biggest
unknowm was; "exactly how much fuel do I have onboard?"
[There is a reason for the 30 and 45 minute reserve rules. They are
there so that you never have to know to the drop how much fuel you have.
They give you a margin of error. A much needed one in this case.]
He knew that when he left he was slightly under full, but how much
under? He pulled out his log book and had a look at it. It showed about
30 minutes of flight from the point where he filled up, to the point
where he landed and where they had left from initially that day. Then he
calculated where they had gone that day and the flight times, and then
checked all that against what the fuel sight tubes actually said. It all
seemd to jive about down to the penny... which is too close when it
comes to fuel and flying over rough terrain.
He had made up his mind, and they were going to give it a shot. He took
out a pen and circled all of the little private fields along the flight
path, just in case. He extended VOR lines to them so he could use that
to better identify them as he flew. He double checked his power settings
chart to figure out what rpm was going to give him the best gas milage.
He fired it up, and off they went.
[What... are we going into battle here or something? Do you have to save
the world tonight? Are we taking the President to the nuclear fall out
shelter before the bombs hit? What's the big godamn emergency? Stop,
turn back, get out the Visa card and spend the night on the ocean
They departed with the flat angle climbout one would use in a race.
Aiming the angle with just enough climb to clear the first set of hills.
They were already out over water, the mouth of the Columbia River, and
visions of other "emergency situations" in the past were entering the
pilots mind. He was already using a somewhat reduced power setting to
conserve a little even while climbing, and the little bird, being
lightly loaded, was performing well.
Half Pint, in all of her worldly wisdom, was monitioring the fuel sight
tubes and barking out the fuel status report about every 10 seconds it
seemed, while Low Time held a dead straight course, monitored their
position on the chart and identified the small "farm airfields" as they
went. They had cleared the first set of hills, and had leveled off while
going to their reduced power "maximum range" cruise setting. At that
point he switched tanks to make sure they were both working like they
were when they departed, and then switched to the lowest tank, with the
plan being to run it all the way dry. Half Pint was watching intently as
her's was the lower tank. Low Time looked over and said, "we'll have to
run your tank dry, then switch over to mine". She got a scared look on
her face giving the impression that maybe if "her tank" went dry, her
half of the airplane would fall down or something. Low Time reassured
her that "everything would be fime", but nobody in the plane that night
really believed a word of it.
As the engine sputtered and tried to quit, he hit the boost pump and
switched to the last tank. The sight tube had some fuel in there, but
not a whole lot. Low Time rocked the wings a bit and watched the sight
tube. He tried to get one more click lean on the mixture knob, but the
engine sagged a little when he did. The engine was as tuned as it was
going to get already, and with no EGT in the plane, engine sag was about
all he had to go by. It was going to be very close, and he started to
calculate the exact distance remaining to Olympia, while switching the
radio over to the tower frequency.
It was getting much darker now, and the tower closed at 7 pm. While
keeping COM1 tuned to the tower, Low Time switched COM2 away from 121.5
and over to the unicom frequency at the airport to see if there was
anyone there to give them some fuel. They were still quite a ways out,
but they were able to hear the tower, so maybe unicom at the FBO could
hear them. "Olympia unicom, american yankee xyz". Nothing. "Olympia
unicom, this is american yankee xyz". Still nothing. With much more
urgency this time, "OLYMPIA UNICOM, THIS IS AMERICAN YANKEE XYZ, DO YOU
READ?" Still nothing. He sitched to the other unicom, and repeated the
attempt, and agin, nothing. Low Time looked at the fuel sight tube.
There was just barely enough fuel to make the little red ball bobble
intermittently. Thoughts of having to spend the night in Olympia were
only blocked out by the thought of running out of gas before getting
Being just a couple minutes before 7 pm., Low Time thought he'd better
call up the tower and see if they would be any help. He thought at least
that way someone would know that they were out there, and supposed to be
landing soon. They were still farther away than the standard call up
would occur from, but it was now or never. "Olympia tower, american
yankee xyz 10 miles to the southwest (he lied), landing with whisky."
"xyz, we will be closing in just a minute or two, at that time you will
need to monitor 124.xx during your entry into the pattern", they
replied. "xyz roger 124.xx, by the way, is there still anyone over at
either of the FBO's?" "xyz, you will just have to try calling them on
either unicom fequency 123.xx or 122.xx." "Yes, I already tried that,
more than once, and got no reply, do you still see any lights on over on
that side of the field?" And in usual ATC fashion they replied with,
"Olympia tower is now closed, tune to...". "Sheesh, a lot of help they
were" he thought.
With the VOR still indicating a straight line to the Airport, and being
about 5 miles out, Low Time once again looked at the fuel site tube. The
little red ball wasn't bobbling at all any more, and the airport still
wasn't in sight. It was a minute or so later that the aiport beacon
finally showed itself, but it still looked so far away. Low Time keyed
the mike to turn on the runway lights. 3 clicks made them come on, but
they were still so dim and distant. OK, how about 5 clicks. That's a
little better. Hell, let's shoot the works... 7 clicks for full
brightness. Yes, much better.
The VASI came into sight, and Low Time set up a slightly high long
straight in approach while reducing power. He wanted to at least be able
to make the runway if the engine quit right there. No Flaps, no power,
just an idling glide pointed at the about a third of the way down a
5400' runway. He was pretty sure he was going to make it now, and tried
to concentrait on flying the airplane and making a decent landing. They
touched down, rolled out and the engine was still running. "Amazing", he
thought as he looked down at the totally empty sight tube.
They looked around and headed for the lit up "76" ball in the distance.
He thought for sure that the engine would quit before they got all the
way over there. As they pulled up to the pumps, and he reached down to
pull the mixture to "lean cut-off", the engine sputtered and died just
as he pulled it out. He looked over at Half Pint, who had been rather
quiet throuhgout the whole ordeal, smiled and gave her a big hug.
"What", she said. "Oh, I just thought I'd give ya a hug, that's all", he
The line boy came out asked the usual stuff, and Low Time grinned and
said "just fill it up till it won't take anymore, it's proably pretty
hungry, we're going to go use the restrooms". "Oh by the way, how late
are you open anyway?" "Well", he said, "We normally close up about now,
but the other FBO with the Cheveron sign up there has a self serve
credit card pump that is open all night." "That's good to know", Low
Time replied. "How about over at Hoquium, do you know when their fuel
closes up?" "Oh, they have a 24 hour credit card pump over there as
well." "It's about the only place out on the coast to get gas after 5
oclock anymore", the line boy replied. "Uh ya, well, that's good to know
too." "I'll have to make a note of that", Low Time said.
The line boy proceeded to put 23.2 gallons into a plane that has 22
From: Johnny <firstname.lastname@example.org>
Subject: Re: Seawind Amphibian
Date: Wed, 09 Sep 1998 05:18:02 -0700
Mike Goodyear wrote:
>Just an update, the seawind that crashed on takeoff did not have a screen
> behind the foam air filter and it was ingested into the engine causing it
> to flood and stop at a hight of about 150ft. During the emergency landing
> the right wing touched first and caused a cartwheel, destroying the
> aircraft.The pilot will be a long time recovering from the crash but he
> also remarked that it was "one strong aircraft"
> We all wish him a speedy recovery.
When I wrote the 'Fuel System Design and Management 101'
article some time back, I think I neglected to include this scenario.
Thinking back now though, I'm pretty sure this exact same thing has
brought down more than a couple other aircraft in the past. Was someone
maintaining this article for their chapter members? I can't recall who
it was. I was hoping that it would get added on to and corrected by
builders as they thought about the subject and designed and built their
own fuel systems. This somewhat common air filter problem should be
added to that list.
-j- (gliders can't run out of fuel, especially if they aready did)
Was there anything in particular that caused the one wing to dip into
the water hard enough to cause the cartwheel? I'm not trying to be
critical of the injured pilot here. Just wondering if this is a trait of
this design. Isn't the wing float supposed to prevent this, even if the
one side does plop in a little hard? Should there be more hull out there
at the end?
From: highflyer <email@example.com>
Subject: Re: Help for choice, plan built?
Date: Tue, 15 Sep 1998 08:29:06 -0500
Owen Davies wrote:
> FWIW. My wife still isn't happy about having a tank in her lap,
> but it looks like an okay compromise to me.
> Owen Davies
Owen made some good points. Typically the early tandem high wing
aircraft had straight gravity feed fuel systems. The best solution
I found I had in my old Taylorcraft DCO about forty years ago.
There was a five gallon header tank behind the instrument panel
above the rudder pedals. This tank had no fuel filler. It had
two fuel lines that ran down from the two wing tanks, one from
either side, that entered it at the ends near the bottom. Above
each of those, at the TOP of the header tank was a vent line that
ran back up to the wing tanks and enterer them near the top front
of the wing tank. Next to where the vent from the header tank
entered the wing there was a "cross vent" line that ran over to
the opposite wing tank. There were two fuel lines coming out of
each wing tank in the bottom. One forward, and one aft. The
line coming out of the aft of the wing tank ran down and forward
along the side of the cockpit. The line coming out of the front
bottom of the wing tank came straight down and joined the line
from the rear of the front tank. The line continued into the
fuel inlet fitting on the bottom end of the header tank.
In the bottom center of the header tank a fuel line came out that
ran down to the gascolator on the bottom front of the firewall.
From there it ran up to the carb on the engine. Where it came out
of the header tank there was a simple brass shutoff ball cock that
could shut off the carb so fuel wouldn't leak through the float
bowl with a seeping needle valve in the carb.
I made the two vent lines that ran from the header tank up to the
wing tanks from clear tygon tubing. When there was fuel in the
wing tanks this vent line would fill up with fuel. As long as the
vent lines, which ran up alongside the braces from the center of the
cowling to the wingroots, were RED, I had fuel in the wings. As the
wing tanks emptied I could see the fuel drop down the vent lines
until it disappeared into the header tank. When that happened I had
exactly one hour of fuel, so it was time to find an airport and
It was a simple system and worked great.
Wing tanks are generally favored for two reasons. The reasoning is,
in the event of an accident, the wings are usually stripped off
before the wreckage comes to a stop, leaving your flammable fuel
behind you. The other reason has to do with loading. All weight
carried in the wings, tends to reduce the bending moment on the
spars at the center section. Weight carried in the fuselage tends
to increase the bending moment. The worst place to put fuel is
behind the passenger area, or beneath the cockpit.
Many wing tank systems work fine without a header tank. However,
the header tank works well.
Make sure that you bring fuel down from wing tanks from both the
forward and the aft ends of the tanks. That ensures feed as the
pitch angle changed.
ALWAYS, when installing a fuel line into a fuel tank, ensure that
there is a finger strainer on the end of the fuel line to catch
and stop anything that gets in the tank that could possibly cause
an obstruction in the line once it enters. Lost an engine on takeoff
once because the finger strainer was missing in a fuel tank. It
could spoil your day as well!
The best way to put a fuel line into a tank is to put a female pipe
threaded socket through the tank wall. Thread a brass fitting into
this socket to fit it to your fuel line, either flare fitting, ot
a tubing connection. In the back of this brass fitting drill a
counterbore just large enough to accept a cylinder rolled from fine
screen wire. Solder an end cap on the screen cylinder, solder the
side seam on the screen cylinder, and then solder the screen cylinder
into the brass fitting. Then thread the whole thing into the tank
fitting. That allows you to pull the fitting and clean and inspect
the tank strainers when you do your annual inspection.