Zero Fuel Weight?

[MichiPilot]

I've recently been flying a great cherokee six and love the thing. Most of my flights have been one one or two people so useful load has not been an issue. Though, I'm planning a flight soon that will carry a few more people. I've seen "zero fuel" weight a few places and am having trouble translating it to the calculation.

I understand that it is essentially the weight above which any additional weight should only be fuel. Is that correct?

Does this change with payload? How do I calculate it? I don't seem to find it in the POH.

Thanks!

 

[JHW]

it's simply how much you can put in the fuselage. Do your W&B and put in zeros for the fuel and see if the resulting gross is over the ZFW. This is one of the rare cases that the name is exactly what it means. The PA32 is one of the very few (only one i can think of) piston singles with a ZFW

speaking of fuel, make sure you follow piper's recommendation about fuel in the tip tanks. You should fill the tips first, and then burn every drop out of the mains before touching the tips. Your top wing skins will thank you.

 

[Henning]

I've recently been flying a great cherokee six and love the thing. Most of my flights have been one one or two people so useful load has not been an issue. Though, I'm planning a flight soon that will carry a few more people. I've seen "zero fuel" weight a few places and am having trouble translating it to the calculation.

I understand that it is essentially the weight above which any additional weight should only be fuel. Is that correct?

Does this change with payload? How do I calculate it? I don't seem to find it in the POH.

Thanks!

Correct. It doesn't really change payload, since payload does not include fuel. Let's say you have a 4300lb GW and a 4000lb Zero fuel weight and a 2500lb empty weight. That means you have a 1500 payload and 1800lb useful load. With 1500lbs in the cabin you can take 50 gallons of fuel giving you about 2.5 hr VFR range with reserves.

If you need more range, you can take weight out of the cabin and add fuel, however you cannot leave fuel behind and add payload for a 30 minute flight.

 

[Subsea]

It has to do with the wings flexing too much. If the wings are empty and the fuselage is too heavy, the wings carrying the entire weight of the fuselage while not carrying much weight themselves, and therefore start flexing closer to the wing root.

Columbias also have a MZFW.

 

[MauleSkinner]

What is the max zero fuel weight (ZFW) of the Cherokee Six? The calculation is simply to add up the airplane itself and everything you're putting in the airplane except fuel. If this total is below max ZFW, you're good.

Then add fuel for the mission to stay below max takeoff weight and still meet any performance requirements you may have (field length, obstacles, etc.).

 

[Stewartb]

Zero fuel weight is a plot on a W&B graph that represents your airplane as loaded with no fuel. A second plot would show the same load with fuel added and that calculated CG. Your CG during a flight will vary on a line between those two points.

 

[flyingron]

The old Brittain (now Osborne) tip tanks originally on the Navion but available for a wide variety of singles (Bonanzas, Commanches) come with a gross weight increase that states that all weight above the original gross weight (plus about ten pounds for the Navion) must be in the tips. As pointed out, carriage of weight out on the other end of the wing has some advantages over dumping it in the fuselage (or close in on the wings).

 

[SkyDog58]

What some folks have a hard time wrapping their heads around for some reason is that you can be well under gross but still be above MZFW.

 

[tlrussell]

What is the max zero fuel weight (ZFW) of the Cherokee Six? The calculation is simply to add up the airplane itself and everything you're putting in the airplane except fuel. If this total is below max ZFW, you're good.

Then add fuel for the mission to stay below max takeoff weight and still meet any performance requirements you may have (field length, obstacles, etc.).

I have a 1973 pa32-300 it's zero fuel weight is 3112lbs. Check your POH.

 

[Einstein376]

Commander Aircraft also use a zero fuel weight for their singles.

Jim

 

[Stewartb]

All airplanes have a zero fuel weight. Some have a limitation for maximum zero fuel weight.

 

[poadeleted20]

For a Cherokee Six, the maximum ZFW may not be in what most folks would call a "POH" (i.e., the "Owner's Manual" or "Owner's Handbook"), but is actually in the Approved Flight Manual (AFM), which is a separate document. It looks like about two dozen 8-1/2x11 typewritten pages, and your plane isn't legal to fly without that document in it.

 

[RotorAndWing]

For a Cherokee Six, the maximum ZFW may not be in what most folks would call a "POH" (i.e., the "Owner's Manual" or "Owner's Handbook"), but is actually in the Approved Flight Manual (AFM), which is a separate document. It looks like about two dozen 8-1/2x11 typewritten pages, and your plane isn't legal to fly without that document in it.

What regulation requires a CAR3 airplane to have an AFM?

 

[Hank S]

What regulation requires a CAR3 airplane to have an AFM?

Typical Ron. Stretch all existing regs to cover any and every possible situation. Comply with every reg in the book, "just to be safe." It's for the children . . .

 

[Let'sgoflying!]

Zero fuel weight is a plot on a W&B graph that represents your airplane as loaded with no fuel. A second plot would show the same load with fuel added and that calculated CG. Your CG during a flight will vary on a line between those two points.

Is that a straight line, in all cases, all airplanes?

 

[Stewartb]

Don't know, but it works that way for mine. Truth told? I use the Aviation W&B app on my iPhone with custom templates for my airplane on big tires and wheel skis. The app automatically plots zero fuel weight and on-board fuel weight on the W&B chart for the airplane. I use it all the time.

A typical W&B shot of a solo flight with the dog. This has been a very handy app.

 

[Gucci Pilot]

http://www.westwingsinc.com/zero.htm

First thing that came up on Google.

 

[Greg Bockelman]

Zero fuel weight is a plot on a W&B graph that represents your airplane as loaded with no fuel. A second plot would show the same load with fuel added and that calculated CG. Your CG during a flight will vary on a line between those two points.

Is that a straight line, in all cases, all airplanes?

There are a lot of absolutes in your question, Dave. Without any empirical data to support it, I would say the answer to your question is "No." It would depend upon the shape of the tank, location in the wing and such.

 

[Kritchlow]

Is that a straight line, in all cases, all airplanes?

No. Swept wing airplanes often have curves. In addition, it can get very unusual because often the wings burn a little first, then center tank, then the wings. It can be a a variety of lines and curves.

 

[poadeleted20]

What regulation requires a CAR3 airplane to have an AFM?

None. But in the case of a Cherokee Six, the requirement was written into the type certificate even though it wasn't legally necessary to do that. In that case, failure to have it aboard is a violation of 14 CFR 91.9(b)(2). If you doubt me, ask AFS-800 (to whom AFS-350 deferred on the issue).

 

[Let'sgoflying!]

No. Swept wing airplanes often have curves. In addition, it can get very unusual because often the wings burn a little first, then center tank, then the wings. It can be a a variety of lines and curves.

zacktly
I understand there are situations where the line can start and end in the box, but be outside, midway during the flight

 

[RotorAndWing]

None. But in the case of a Cherokee Six, the requirement was written into the type certificate even though it wasn't legally necessary to do that. In that case, failure to have it aboard is a violation of 14 CFR 91.9(b)(2). If you doubt me, ask AFS-800 (to whom AFS-350 deferred on the issue).

It would be impossible to write a violation on this, since there is no applicable regulation requiring such a document. See FAA Order 2150.3B "on point". Good luck on trying to get such a violation through legal.


The FAA doesn't write the TCDS, the manufacturer does. The manufacturer writes a TCDS as a way that they will comply with the pertinent and applicable regulations.

Since neither -350 or -800 have addressed this in guidance, and there is already guidance that contradicts their "opinion" I'm not to worried about it.

 

[BillTIZ]

It would be impossible to write a violation on this, since there is no applicable regulation requiring such a document. See FAA Order 2150.3B "on point". Good luck on trying to get such a violation through legal.


The FAA doesn't write the TCDS, the manufacturer does. The manufacturer writes a TCDS as a way that they will comply with the pertinent and applicable regulations.

Since neither -350 or -800 have addressed this in guidance, and there is already guidance that contradicts their "opinion" I'm not to worried about it.

Thanks for the insight. I often refer to the TCDS or the Aircraft (Glider) POH/AFM or other documentation to determine if the "book" needs to be in the glider. Some specifically states that it must be, others make no mention so I leave it out. All pertinent data on those gliders is posted in the cockpit.

 

[poadeleted20]

It would be impossible to write a violation on this, since there is no applicable regulation requiring such a document. See FAA Order 2150.3B "on point". Good luck on trying to get such a violation through legal.


The FAA doesn't write the TCDS, the manufacturer does. The manufacturer writes a TCDS as a way that they will comply with the pertinent and applicable regulations.

Since neither -350 or -800 have addressed this in guidance, and there is already guidance that contradicts their "opinion" I'm not to worried about it.

R&W is wrong on this issue in more ways than I have interest in listing. Anyone who wants to know the actual FAA position on this need only ask the FAA. Suffice it to say that if you are caught flying an airplane whose type certificate requires a flight manual on board (and a Cherokee Six is such an airplane) without that flight manual, according to three sources actually in the FAA (two in Flight Standards at HQ), you will be considered in violation of 91.9. Anyone wishing confirmation should contact AFS-350, AFS-800, or an Inspector at their local FSDO.

 

[Stewartb]

Do you guys think a pilot's common sense should require the manuals? I don't think many owners given the proper manuals would opt to leave them out.

Here's the TCDS. The references to AFM and POH stuff is in the final 3 pages.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/44c795c1c122b21286257d74004d1952/$FILE/A3SO_Rev_33.pdf.pdf

 

[poadeleted20]

And please note that the requirement for the flight manual is in the Required Equipment section of the TCDS. Further, if you look at that manual, you will see that it is signed by the FAA Aircrft Certification Office and includes an explicit requirement that it be on board.

 

[kgruber]

Is that a straight line, in all cases, all airplanes?

No. I once graphed the moment diagram for fuel in a King Air 200. There were sections that were a curved line and some sections straight.

For my simplified W&B application I approximated the curves with straight lines. The FAA looked at it and approved it for the W&B calculations required for PT135 flight.

 

[RotorAndWing]

R&W is wrong on this issue in more ways than I have interest in listing. Anyone who wants to know the actual FAA position on this need only ask the FAA. Suffice it to say that if you are caught flying an airplane whose type certificate requires a flight manual on board (and a Cherokee Six is such an airplane) without that flight manual, according to three sources actually in the FAA (two in Flight Standards at HQ), you will be considered in violation of 91.9. Anyone wishing confirmation should contact AFS-350, AFS-800, or an Inspector at their local FSDO.

I took the time to call an old friend who is now a Regional Counsel and discuss this with him.

As I stated earlier, and he agreed, the TCDS is not a regulatory document. It is a document that states how the manufacturer complies with the regulations in certification. Without a corresponding regulation, there is no requirement, it's very simple.

A Cherokee Six is a CAR 3 aircraft. It's required markings and placards are required by CAR 3.

91.9 Civil aircraft flight manual, marking, and placard requirements.

(b) No person may operate a U.S.-registered civil aircraft—
(1) For which an Airplane or Rotorcraft Flight Manual is required by §21.5 of this chapter unless there is available in the aircraft a current, approved Airplane or Rotorcraft Flight Manual or the manual provided for in §121.141(b); and
(2) For which an Airplane or Rotorcraft Flight Manual is not required by §21.5 of this chapter, unless there is available in the aircraft a current approved Airplane or Rotorcraft Flight Manual, approved manual material, markings, and placards, or any combination thereof.

Now according to the FAA Lawyer, Ron is ignoring that last 4 words. Since CAR 3 has already set forth the requirement in regulation for the Cherokee Six to use markings and placards, the "or any combination thereof" is satisfied.

I took it a bit further and asked if it was possible to write an enforcement on this using 91.9 alone. He laughed for a moment, then said "Without the corresponding regulation in CAR 3, it would be impossible to cite 91.9".


Here is the actual written guidance on the subject, from AFS-300 that contradicts Ron's supposed advice from the same organization.

FAA Order 8620.2A "Applicability and Enforcement of Manufacturer’s Data"

7. TCDS

Consistent with 14 CFR, a TCDS is part of a product’s type certificate (TC). A TCDS is a summary of the product’s type design.It is used primarily by authorized persons during initial or recurrent issuance of a Standard Airworthiness Certificate. It is neither a regulation, a maintenance requirements document, or a flight manual document. As such, for aircraft holding a valid and current airworthiness certificate, a TCDS should not be used as a sole source to determine what maintenance is required or what the flight operations requirements are. Any language on a TCDS, by itself, is not regulatory and is simply not enforceable. There must be a corresponding rule to make any language on the TCDS mandatory. For example, there is a mention of “operating limitations” on most TCDS. The corresponding rule for “operating limitations” is 14 CFR § 91.9(a) which states, “Except as provided in paragraph (d) of this section, no person may operate a civil aircraft without complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual, markings, and placards, or as otherwise prescribed by the certificating authority of the country of registry.” Without § 91.9, the TCDS requirement to comply with operating limitations would not be enforceable.

Read that paragraph very carefully, it's very succinct and leaves nothing to "interpretation".

I've provided actual written guidance on the subject as per a FAA ORDER. Ron L gives you "I was told by........" without anything to back that up, no Order, Notice or even a Memo on a FAA Letterhead signed by someone.

You decide.

 

[RotorAndWing]

Thanks for the insight. I often refer to the TCDS or the Aircraft (Glider) POH/AFM or other documentation to determine if the "book" needs to be in the glider. Some specifically states that it must be, others make no mention so I leave it out. All pertinent data on those gliders is posted in the cockpit.

I take it your gliders are CAR aircraft.

 

[JHW]

I'm sure no FAR expert, but I've flown probably 30 US-registered PA32's, some I owned, most as box haulers, and i can't recall any of them having an AFM separate from the owner's manual or whatever it's called.

 

[poadeleted20]

I took the time to call an old friend who is now a Regional Counsel and discuss this with him.

As I stated earlier, and he agreed, the TCDS is not a regulatory document. It is a document that states how the manufacturer complies with the regulations in certification. Without a corresponding regulation, there is no requirement, it's very simple.

R&W is correct as far as he goes. However, he fails to note the following in FAA Order 8620.2A:

Any language on a TCDS, by itself, is not regulatory and is simply not enforceable. There must be a corresponding rule to make any language on the TCDS mandatory. For example, there is a mention of "operating limitations" on most TCDS. The corresponding rule for "operating limitations" is 14 CFR § 91.9(a) which states, "Except as provided in paragraph (d) of this section, no person may operate a civil aircraft without complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual, markings, and placards, or as otherwise prescribed by the certificating authority of the country of registry." Without § 91.9, the TCDS requirement to comply with operating limitations would not be enforceable

IOW, there is a regulation which makes TCDS requirements enforceable, specifically, 91.9. And while in the past he has argued that TCDS "Notes" are not enforceable, the TCDS requirement for the flight manual is in "Required Equipment", not "Notes". Further, the flight manual itself is signed by the FAA Aircraft Certification Office, making it "otherwise prescribed by the certificating authority of the country of registry".

 

[poadeleted21]

I'm sure no FAR expert, but I've flown probably 30 US-registered PA32's, some I owned, most as box haulers, and i can't recall any of them having an AFM separate from the owner's manual or whatever it's called.

I was surprised to learn that my 1963 Cherokee was supposed to have one. Piper happily mailed it to me for $250.

 

[RotorAndWing]

R&W is correct as far as he goes. However, he fails to note the following in FAA Order 8620.2A:

or as otherwise prescribed by the certificating authority of the country of registry."

IOW, there is a regulation which makes TCDS requirements enforceable, specifically, 91.9. And while in the past he has argued that TCDS "Notes" are not enforceable, the TCDS requirement for the flight manual is in "Required Equipment", not "Notes". Further, the flight manual itself is signed by the FAA Aircraft Certification Office, making it "otherwise prescribed by the certificating authority of the country of registry".

That is so laughable. But you keep stretching and contorting this to fit your agenda.

 

[kgruber]

Every Piper I've even flown, including many straight from Lock Haven, have had an AFM required in the airplane. Here is the front page of the AFM required in my 1967 Cherokee 180C.

 

[RotorAndWing]

Every Piper I've even flown, including many straight from Lock Haven, have had an AFM required in the airplane. Here is the front page of the AFM required in my 1967 Cherokee 180C.

What's at question here, and what Ron can't understand, is yes, the manufacturer can produce that document and submit it to the FAA for approval, and the FAA can approve it. However, there is no regulation requiring that document to be onboard the aircraft.

The regulations in question are certification, and under CAR 3 with the airplane above, all that was required was placards and markings to certify the aircraft. Even 91.9 specifies that with the four words Ron refuses to acknowledge in the regulation.

Here is 14 CFR Part 21.5

21.5 Airplane or Rotorcraft Flight Manual.

(a) With each airplane or rotorcraft not type certificated with an Airplane or Rotorcraft Flight Manual and having no flight time before March 1, 1979, the holder of a type certificate (including amended or supplemental type certificates) or the licensee of a type certificate must make available to the owner at the time of delivery of the aircraft a current approved Airplane or Rotorcraft Flight Manual.

Here's an older AC that discusses the same issue.

BTW, FWIW, your manual that you pictured is not approved any longer. The registration number that was crossed out and replaced with the handwritten number invalidates that document. For it to be approved it has to be rewritten, resubmitted for approval with the updated information.

 

[kgruber]

I can see your reasoning, and my Cherokee has placards plastered all over the place.

However, there is much information in the AFM which is not placarded. Like the moment diagram.

Therefor, to have ALL the information Piper wrote in their AFM, I need to have the complete manual in the airplane.

 

[Stewartb]

CAR3 addresses AFMs and operating limitations. My own interpretation is that regardless of RW's reference to AFMs not being enforceable, the CARs definitely require that they were supplied to every airplane owner and are required equipment for the purpose of defining limitations. In airplanes with dual standard and utility category approval that's undeniable after reviewing the CARs.
http://www.supercub.org/photopost/data/500/CAR-PART3.pdf

I don't know how a competent pilot without experience in my airplane could be expected to safely operate my airplane without having the POH and supplements available. And my 1975 C-180 TCDS does require having the POH in the required equipment section. Common sense would have it there even in the absence of ANY regulations.

 

[kgruber]

BTW, FWIW, your manual that you pictured is not approved any longer. The registration number that was crossed out and replaced with the handwritten number invalidates that document. For it to be approved it has to be rewritten, resubmitted for approval with the updated information.

I'm not buying into that either. "N" numbers change all the time. Serial numbers don't. I'd say the AFM follows the serial number.

 

[Stewartb]

More information......

200. Definition Of The Term “Airworthy” for U.S. Type-Certificated (TC) Aircraft.
Although the term “airworthy” is defined in 14 CFR § 3.5(a), a clear understanding of its meaning is essential for use in the FAA’s airworthiness certification program. Below is a summary of the conditions necessary for the issuance of an airworthiness certificate. A review of case law relating to airworthiness reveals two conditions that must be met for an aircraft to be considered “airworthy.” Title 49, United States Code (49 U.S.C.) § 44704(c) and
14 CFR § 21.183(a), (b), and (c) state that the following two conditions necessary for issuance of an airworthiness certificate:
a. The aircraft must conform to its type design. Conformity to the type design is considered attained when the aircraft configuration and the engine, propeller, and articles installed are consistent with the drawings, specifications, and other data that are part of the TC. This includes any supplemental type certificate (STC) and repairs and alterations incorporated into the aircraft.
b. The aircraft must be in a condition for safe operation. This refers to the condition of the aircraft relative to wear and deterioration, for example, skin corrosion, window delamination/crazing, fluid leaks, and tire wear.
Note: If one or both of these conditions are not met, the aircraft would not be considered airworthy. Aircraft that have not been issued a TC must meet the requirements of paragraph 200b of this order

source: http://www.faa.gov/documentLibrary/media/Order/8130.2G .pdf

 

[RotorAndWing]

I can see your reasoning, and my Cherokee has placards plastered all over the place.

However, there is much information in the AFM which is not placarded. Like the moment diagram.

Therefor, to have ALL the information Piper wrote in their AFM, I need to have the complete manual in the airplane.

True, it's nice to have it all in one place, no arguing that. There's just no regulation requiring it.

Actually, if you want to drill down further into this topic, the main reason the manufacturers came up with and got the manuals "approved" was to meet requirements for Part 135. Rather than each operator having to develop an AFM and submit it for approval, the manufacturer developed the AFM and got blanket approval, so basically all the operator must do is submit this manual as part of their package. This also gave a standardization on performance tables and such so that one operator was not developing his own rendition with questionable data.

Look at it this way too. A friend has a Cherokee Six he uses on Part 135 occasionally. He loans it to you to fly Part 91, and when you get in the airplane the checklist says "FAA Accepted". Do you have to use that checklist or can you use your own or the checklist on the panel placard?