Empty Weight

There are no rules when the owners are making entries.
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Bullhockey. An owner performing maintenance is bound by the same rule you are as an A&P.

43.9 begins:
(a) Maintenance record entries. Except as provided in paragraphs (b) and (c) of this section, each person who maintains, performs preventive maintenance, ...
 
flyingron said:
Bullhockey. An owner performing maintenance is bound by the same rule you are as an A&P.

43.9 begins:
(a) Maintenance record entries. Except as provided in paragraphs (b) and (c) of this section, each person who maintains, performs preventive maintenance, ...
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Are all entries maintenance ?
Don't thing so.
 
Tom-D said:
Are all entries maintenance ?
Don't thing so.
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What entries besides maintenance entries goes into a maintenance record?

Are you saying that weighing an aircraft to determine the official weight and balance is not a maintenance activity? Or are you saying that determining the empty weight cg is not a maintenance activity as long as scales are not involved, ie. calculating a new empty weight cg mathematicaly after a change in equipment? I think that an owner operator can certainly determine the loaded cg and in fact is required to do so prior to flight but determing the empty weight cg is not preventive maintenance and must be done by an A&P or at the very least, supervised by an A&P as it involves maintenance not covered under preventive maintenance.
 
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Witmo said:
What entries besides maintenance entries goes into a maintenance record?
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anything owner likes. How about corrections. seems like A&Ps can't math. Can a owner correct these errors ?

Can any owner record history ?
If not there are a lot of stuff that is in logs that needs to be erased.
 
Witmo said:
Are you saying that weighing an aircraft to determine the official weight and balance is not a maintenance activity?
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It is, but any owner can place anything they like in the logs, they are owner's property.

there separate maintenance, and log entries.
 
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Tom-D said:
It is, but any owner can place anything they like in the logs, they are owner's property.

there separate maintenance, and log entries.
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No, there are not separate maintenance and log entries. All maintenance requires a log entry and anything other than maintenance is extraneous in a maintenance record (aka maintenance log) book. I'll concede that an owner can write whatever garbage he wants to in his own log books and they become "log entries" but it doesn't substitute for required maintenance entries signed by someone authorized to do the work and return to service. I'd also hazard a guess that extraneous entries in the maintenance log could detract from the value of the aircraft. An owner could record a new empty weight CG in the log just like he could record that he replaced a cylinder. Unless an A&P supervised and signed the return to service, both entries would violate part 43 since neither are preventive maintenance.
 
Tom-D said:
This isn't an issue of how much gas is in the tank. it is an issue of what the manual says to do.

do you know how to get every of gas your tanks. I will bet getting all the gas out isn't how you do W&B.
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Yes, do what the manual says. What I’m talking about is this, “...If there are no specific instructions, drain the fuel until the fuel quantity gauges read empty when the aircraft is in level-flight attitude. See post #5. Nothing was said about getting all the gas out of the tank. It’s about getting the ‘usable’ fuel out, leaving the ‘unusable’ to be part of the empty weight.
 
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Witmo said:
No, there are not separate maintenance and log entries. All maintenance requires a log entry and anything other than maintenance is extraneous in a maintenance record (aka maintenance log) book. I'll concede that an owner can write whatever garbage he wants to in his own log books and they become "log entries" but it doesn't substitute for required maintenance entries signed by someone authorized to do the work and return to service. I'd also hazard a guess that extraneous entries in the maintenance log could detract from the value of the aircraft. An owner could record a new empty weight CG in the log just like he could record that he replaced a cylinder. Unless an A&P supervised and signed the return to service, both entries would violate part 43 since neither are preventive maintenance.
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With that I give up. you fail to under the owner can place anything they want in the logs.

bye
 
luvflyin said:
Yes, do what the manual says. What I’m talking about is this, “...If there are no specific instructions, drain the fuel until the fuel quantity gauges read empty when the aircraft is in level-flight attitude. See post #3. Nothing was said about getting all the gas out of the tank. It’s about getting the ‘usable’ fuel out, leaving the ‘unusable’ to be part of the empty weight.
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there are many aircraft that have no instructions, either for the fuel to use for W&B and the method to compute the W&B.
But when there are those instructions should be used.
That is the reason the 43,13 was published.
and the reason the directive is a AC not a SB or directive

Plus, there is no published amount of fuel for gauge calibration. all it says is the gauge must to read when is empty.
 
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birdus said:
... If there are no specific instructions, drain the fuel until the fuel quantity gauges read empty when the aircraft is in level-flight attitude. Any fuel remaining in the system is considered residual or unusable fuel and is part of the aircraft empty weight."...
Thanks.
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Determining when you've drained all the usable fuel and left the unusable is very difficult since unusable fuel is that fuel that cannot be used in all normal flight attitudes--not just when the aircraft is level. Oftentimes, all the fuel can be burned if you maintain level flight. Cessna 150s have 3.5 gallons of unusable fuel according to Cessna. I've seen several accidents where the pilot ran out of fuel and the investigators noted there was not a drop of fuel remaining, indicating that all the "unusable" fuel was in fact used. If that pilot had not maintained level flight, say he began a climb or a descent earlier or some other normal flight attitude besides level flight, there might have been some unusable fuel left after the engine stopped due to the placement of the fuel pickup(s) in the tank and the subsequent unporting of said pickups.

For the above reason, it's probably best to fill the fuel tanks and subtract the weight and cg of whatever the manufacturer states is the usable fuel for that airframe when weighing the aircraft for an updated empty weight cg.
 
Tom-D said:
With that I give up. you fail to under the owner can place anything they want in the logs.

bye
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You really need to work on your reading comprehension.
 
Drain the tanks from the fuel line, then hit the fuel tank sumps, I bet less than a pint came out of the sumps on Cessna 177 I weighed. Jacked and leveled the airplane and hit all the sumps again fuel strainer, header tank and all. Look in tanks with a flashlight. That’s close enough to dry for me.
 
The only way to get the unusable fuel level is to completely drain the tanks, including getting the last of it by removing the sump drains, and then adding the unusable amount as per the TCDS or the AFM. Fuel gauges, even really accurate fuel gauges, are going to be off by a few pounds at least, and depending on aircraft attitude, they could be off a lot.
 
pigpenracing said:
My Cessna 175 says 52 gallons of fuel and 42 is usable. Kinda strange 5 gallons per side is unusable!
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Tank configuration can do that to you. Don't count on that last ten gallons; I know of a 150 that ran out of fuel on a full-flap, power-off approach because the dipstick was calibrated in total fuel instead of usable, and they ran out because they thought they still had reserve. With the nose well down, the unsuable fuel can't reach the outlet to the engine.
 
you can also rent scales and do it yourself. you could syphon or sump tanks and then remove the hose from the aux pump and run it til it cavitates then what you have left is literally unusable. That said, I wouldnt be too concerned about a plane being weighed full then calculated out. Defueling takes time and if you have to pay someone to do it the costs will go up.
 
Consider the following:

Ok..so you are fueling a taildragger like a 180 Cessna at the fuel pump area. When you have fuel to the top of the caps, is this the same as max fuel capacity in a level position....probably not, but it is realistically all we can add to the tank on level ground. I doubt you could add much more, but when weighing at full fuel weight, will this matter ?

Also, some test criteria calls for checking fuel flow in determining usable vs unusable fuel ...to find at what point the fuel flow drops below 150 percent of max fuel burn.

This is also the criteria used to determine if a high wing airplane such as a Cessna195 requires an engine driven fuel pump vs only gravity feed from the tanks.

I also fly a Bonanza with aux tanks in the wings placarded for “ level flight
only “. I know a guy who purchased a Bonanza and tried to takeoff with aux tanks..the engine quit when he rotated....might have saved his life...he read the POH after that happened.

All aircraft are different..research is your key to success.
 
Scott MacMoyle said:
you can also rent scales and do it yourself. you could syphon or sump tanks and then remove the hose from the aux pump and run it til it cavitates then what you have left is literally unusable. That said, I wouldnt be too concerned about a plane being weighed full then calculated out. Defueling takes time and if you have to pay someone to do it the costs will go up.
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You’ll lose useful load. Manufacturing makes sure tanks hold the published amount and then some (you can imagine the lawsuits if you shorted someone fuel capacity).


Tom
 
Doug Reid said:
Consider the following:

Ok..so you are fueling a taildragger like a 180 Cessna at the fuel pump area. When you have fuel to the top of the caps, is this the same as max fuel capacity in a level position....probably not, but it is realistically all we can add to the tank on level ground. I doubt you could add much more, but when weighing at full fuel weight, will this matter.
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Measure with a micrometer, cut with an axe.

Since you can’t fuel a tail dragged in a level position, it doesn’t make sense to fill it when level just to weigh it.
 
Dan Thomas said:
Some airplanes, like Citabrias and later 172s and a lot of larger Cessnas had outlets at the front and back, with the lines running down the doorposts and teeing together down low. Not much fuel unable to leave the tank in that setup.
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For those who are interested, that's how the Luscombe is set up.
 
Dan Thomas said:
If the OP's Luscombe has wing tanks, I'd bet there's unusable fuel. The TCDS is silent on it.
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A few folks on the facebook Luscombe group (frequented by the foremost Luscombe experts on the planet) said ALL the fuel in the Luscombe is usable. I may not understand exactly what that means or if it's backed up by government bureaucrats, but that's what they said.
 
Regardless how the aircraft is weighed there still is a requirement to follow an acceptable method per the performance requirements in Part 43. Most guidance points to using the OEM procedures, but any FAA procedures work as well. As to weighing with full fuel, in my experience, unless there's a published fuel qty/moment available for the aircraft, it usually is quicker and easier to defuel, drain and weight vs calculating the moment on full tanks.
 
Bell206 said:
Regardless how the aircraft is weighed there still is a requirement to follow an acceptable method per the performance requirements in Part 43. Most guidance points to using the OEM procedures, but any FAA procedures work as well. As to weighing with full fuel, in my experience, unless there's a published fuel qty/moment available for the aircraft, it usually is quicker and easier to defuel, drain and weight vs calculating the moment on full tanks.
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In this case,, the fuel tanks were removed, cleaned, repaired, and installed, isn't it better, to fill the tanks, then do the math?
 
Tom-D said:
the fuel tanks were removed, cleaned, repaired, and installed, isn't it better, to fill the tanks, then do the math?
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In my experience, no. Regardless whether a W&B was needed after that type of fuel tank mx I would always drain the fuel out to check for any debris/FOD and verify empty quantity readings. I'm just not a fan of full fuel weighing on light aircraft especially when you have to calculate the fuel moments and weight.
 
Bell206 said:
In my experience, no. Regardless whether a W&B was needed after that type of fuel tank mx I would always drain the fuel out to check for any debris/FOD and verify empty quantity readings. I'm just not a fan of full fuel weighing on light aircraft especially when you have to calculate the fuel moments and weight.
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You lost me when you stared talking about debris and FOD in clean tanks.
When we removed bags in the 182/185 the fuel is always found. it is never emptied completely
 
Tom-D said:
You lost me when you stared talking about debris and FOD in clean tanks.
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I believe my words were "after that type of of fuel tank mx." Never said it was in the tank. But a number of times found FOD/debris downstream after mx in the gascolator or other areas from the tank removal/install process. In one case the tank hoses were not changed and the new, clean tank fittings shaved copious amount of rubber from the interior of the old hoses during install. On that one the engine quit during ground run. But hey, that's just me.;)
 
Tom-D said:
In this case,, the fuel tanks were removed, cleaned, repaired, and installed, isn't it better, to fill the tanks, then do the math?
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In that case, why not just add what the book says is unusable fuel and be done with it? No additional mathematics necessary.
 
Greg Bockelman said:
In that case, why not just add what the book says is unusable fuel and be done with it? No additional mathematics necessary.
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because the fuel empty system always require more fuel to fill than the tanks.

Probably the 170 would take 2 gallons more than just the tanks, fill the system, the deduct the amount of the tanks.
and it worse when fuel bags are used, because of the wrinkles
 
Tom-D said:
because the fuel empty system always require more fuel to fill than the tanks.

Probably the 170 would take 2 gallons more than just the tanks, fill the system, the deduct the amount of the tanks.
and it worse when fuel bags are used, because of the wrinkles
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I don't think you'd get two gallons out of the tubing and strainer on a 170 or any light airplane. Even the header tank in a 185 doesn't hold that much.
 
Dan Thomas said:
I don't think you'd get two gallons out of the tubing and strainer on a 170 or any light airplane. Even the header tank in a 185 doesn't hold that much.
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probably, but still it enough to compute for W&B.

still the fuel system should be full and computed for W&B
 
luvflyin said:
Yes, do what the manual says. What I’m talking about is this, “...If there are no specific instructions, drain the fuel until the fuel quantity gauges read empty when the aircraft is in level-flight attitude. See post #5. Nothing was said about getting all the gas out of the tank. It’s about getting the ‘usable’ fuel out, leaving the ‘unusable’ to be part of the empty weight.
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As a mechanic, I can say that this would be a silly way to get unusable fuel. Those gauges are nowhere near accurate enough for that in most airplanes. The typical sender has a float on an arm that swings up and down and changes a resistance that varies current that works the gauge. In many airplane the unusable fuel is a gallon or two per side, and by the time you get down to a gallon or so the float is against its stop (proper) or striking the bottom of the tank (improper.) The float doesn't ride entirely on the surface of the fuel; it has weight and so it sinks halfway so that when it stops moving downward there's still too much fuel.

Moreover, ground attitude can give gauge readings different than flight attitude readings. The first time you ever do an actual W&B, you're astonished at the airplane's attitude on the scales once it has been levelled as per the maintenance manual. The nose is very low. When a 185 is on 6" tall scales and levelled, you can walk under the aft fuselage.

The requirement is that the gauge read Empty when unusable fuel level is reached. In practice, the gauge reads empty before that level is reached and the powers that be seem fine with that; they just don't want the gauge reading 1/8 full when there is only unusable fuel left.

The ONLY way to get the right unusable fuel level is to drain every drop out of the system and add the unusable as specified in the TCDS. If it's not specified, it's the difference between the usable (posted on the selector) and the total (posted near the fuel filler). Most TCDS have placard requirements and that's where you find the numbers.
 
Dan Thomas said:
As a mechanic, I can say that this would be a silly way to get unusable fuel. Those gauges are nowhere near accurate enough for that in most airplanes. The typical sender has a float on an arm that swings up and down and changes a resistance that varies current that works the gauge. In many airplane the unusable fuel is a gallon or two per side, and by the time you get down to a gallon or so the float is against its stop (proper) or striking the bottom of the tank (improper.) The float doesn't ride entirely on the surface of the fuel; it has weight and so it sinks halfway so that when it stops moving downward there's still too much fuel.

Moreover, ground attitude can give gauge readings different than flight attitude readings. The first time you ever do an actual W&B, you're astonished at the airplane's attitude on the scales once it has been levelled as per the maintenance manual. The nose is very low. When a 185 is on 6" tall scales and levelled, you can walk under the aft fuselage.

The requirement is that the gauge read Empty when unusable fuel level is reached. In practice, the gauge reads empty before that level is reached and the powers that be seem fine with that; they just don't want the gauge reading 1/8 full when there is only unusable fuel left.

The ONLY way to get the right unusable fuel level is to drain every drop out of the system and add the unusable as specified in the TCDS. If it's not specified, it's the difference between the usable (posted on the selector) and the total (posted near the fuel filler). Most TCDS have placard requirements and that's where you find the numbers.
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How about just draining at the inlet to the fuel pump. Or the fuel selector valve. Someplace where what is not usable won’t get to and remain in the tanks. To be weighed as ‘unusable.’
 
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