Weight and Balance Changes (Split from backseat removal)

[Bruce Fenstermacher]

43.13 App A (a)(1)(xi) Changes to the empty weight or empty balance which result in an increase in the maximum certificated weight or center of gravity limits of the aircraft.

George, read the entire sentence not just the first half. The key that makes this part kick in is: which result in an increase in the maximum certificated weight or center of gravity limits of the aircraft.

So if the change does not increase the maximum certificated weight or change the certificated center of gravity limits then this FAR does not apply.

The original question was can a pilot/owner remove wheel pants, 6.00-x tires, and replace the tires with 8.00-x tires and log the maintenance as well as change the W&B.

I say yes and I've not been shown where a FAR says otherwise. I've also not found where it says a mechanics license is required to perform an actual W&B on an airplane but I have conceded that is probably the case.

The there maybe other reasons the rear seat might not be able to be removed and the aircraft flown such as the 4plc certification you mention Geroge so lets remove that example from the question.

[jrenwick]

Here's a link to an FAA book on weight and balance: http://www.faa.gov/library/manuals/airc ... 083-1A.pdf

I'm not sure it answers this particular question.

[steve grewing]

Part 43 Appendix A item 18 seems relevant: "Replacing wheels and skis where no weight and balance computation is involved" is preventive maintenance that can be logged by a pilot-owner. Changes to the W&B sheet carried in the airplane isn't one of the "PM" items listed in Appendix A, so it seems to me that would have to be logged by an AMT.

I would conclude that removing wheel pants permanently and replacing 600x6 tires with 800x6 would require a W&B change, and so can only be signed off by an AMT.

Best Regards,

John

My thoughts exactly.
Changing a tire is preventative maintenance. Replacing one with a different sized tire is maintenance. Removing wheel pants is maintenance. I may be wrong but I suspect the local FSDO Airworthiness Safety Inspector whose 170 is hangared behind mine probably takes that one line of the appendix quite literal. If I see him tomorrow, I'll ask him. Though he does have gray hair and common sense, he like any ASI can nail you to the wall over the placement of a comma if attitudes degrade. The way I understand the reg's a pilot is not authorized to amend the basic empty weight (BEW) of an aircraft. However, he/she is authorized to tell me the weight at which he/she is operating said aircraft at, based on a properly computed and recorded BEW. I think the reg's that would get you in trouble are the ones defining who is authorized to record the action taken, not what was done. I suspect if pilots could sign off the action in question a lot of A&P's, repair stations, etc. would weigh a plane, provide that information to the pilot and tell him to have a good day. Thus relieving themselves of the liability.
I don't recall anything in my pilot training/testing requiring me to demonstrate the ability to compute a CG and BEW following a properly altered conditional change to an aircraft. But I clearly recall them in the A&P written and oral and practical exams. Agreed the last two are anticdotal arguments for sure.

Steve

[Bruce Fenstermacher]

I'll be interested to hear what your FAA neighbor has to say.

Actually Steve I've run across more than a few basic empty weights calculated wrong by A&Ps. I might be shown to be wrong but I've corrected every one that where associated with my aircraft.

[GAHorn]

43.13 App A (a)(1)(xi) Changes to the empty weight or empty balance which result in an increase in the maximum certificated weight or center of gravity limits of the aircraft.

George, read the entire sentence not just the first half. The key that makes this part kick in is: which result in an increase in the maximum certificated weight or center of gravity limits of the aircraft.

So if the change does not increase the maximum certificated weight or change the certificated center of gravity limits then this FAR does not apply.

The original question was can a pilot/owner remove wheel pants, 6.00-x tires, and replace the tires with 8.00-x tires and log the maintenance as well as change the W&B.

I say yes and I've not been shown where a FAR says otherwise. I've also not found where it says a mechanics license is required to perform an actual W&B on an airplane but I have conceded that is probably the case.

The there maybe other reasons the rear seat might not be able to be removed and the aircraft flown such as the 4plc certification you mention Geroge so lets remove that example from the question.

Bruce I did read the entire sentence the first time, ...you are adding words to the comment when you alter it to read "certificated center of gravity". That's not the same. (Or perhaps your copy of FARs is not an official issue? The original wording is: "(xi) Changes to the empty weight or empty balance which result in an increase in the maximum certificated weight or center of gravity limits of the aircraft." From the official gov't printing office website http://ecfr.gpoaccess.gov/cgi/t/text/te ... 49&idno=14 )

A change of empty wt, OR CG is all that is req'd to make an alteration a Major alteration ...(which requires a Form 337.) Any minor maintenance or alteration does NOT require a Form 337. These are pivotal points.
All Form 337's must be signed by an authorized person, who is: a certificated repairman (Repair station or A&P) and/or an A&P with Inspection Authority. The bottom line is that a pilot may not remove the rear seat except to reupholster it and reinstall it under the provisions of FAR 43 Appdx A, Preventive MX.... and he may NOT remove it permanently for purposes of flight unless he is a person authorized to execute a Form 337. (I do not think it appropriate to remove an essential element of this discussion that was a part of the original thread involving Wt and Bal. computations and who may perform them, since this topic is split from that one. I believe it is incorrect, in that the original thread's opening message was not about tires....virtually the entire original thread was about rear seat removal and who could do that....as is this thread, which barely mentions tires except as an example.) The opening comment was:

I want to take out the backseat or 170B for my vacation. I am sure it isn't that big of a chore, but I thought I would ask for some guidance before trying to learn as you go. Any help? Larry

To which you concluded:

...Oh nearly forgot. Get out your paperwork and record the seat as being removed and adjust your W&B.

The owner of the aircraft is ultimately responsible for the airworthiness and the keeping of maintenance records. (Regardless of who is authorized to perform maintenance.) The difference is: That all persons authorized to perform maintenance who do so MUST record in the aircraft records the extent of the maintenance they performed.
If that person happens not to be the owner/pilot....then that person is responsible for recording any wt/bal changes to the aircraft (i.e., in the log entry) and supplying that information to the owner. The owner however, is still responsible for the record-keeping and therefore he/she is authorized to issue changes to wt/bal records...he/she is required to do so in fact, should the repairman fail to do so.)

[GAHorn]

Part 43 Appendix A item 18 seems relevant: "Replacing wheels and skis where no weight and balance computation is involved" is preventive maintenance that can be logged by a pilot-owner. Changes to the W&B sheet carried in the airplane isn't one of the "PM" items listed in Appendix A, so it seems to me that would have to be logged by an AMT.

I would conclude that removing wheel pants permanently and replacing 600x6 tires with 800x6 would require a W&B change, and so can only be signed off by an AMT.

Best Regards,

John

My thoughts exactly.
Changing a tire is preventative maintenance. Replacing one with a different sized tire is maintenance. Removing wheel pants is maintenance. I may be wrong but I suspect the local FSDO Airworthiness Safety Inspector whose 170 is hangared behind mine probably takes that one line of the appendix quite literal. If I see him tomorrow, I'll ask him. Though he does have gray hair and common sense, he like any ASI can nail you to the wall over the placement of a comma if attitudes degrade. The way I understand the reg's a pilot is not authorized to amend the basic empty weight (BEW) of an aircraft. However, he/she is authorized to tell me the weight at which he/she is operating said aircraft at, based on a properly computed and recorded BEW. I think the reg's that would get you in trouble are the ones defining who is authorized to record the action taken, not what was done. I suspect if pilots could sign off the action in question a lot of A&P's, repair stations, etc. would weigh a plane, provide that information to the pilot and tell him to have a good day. Thus relieving themselves of the liability.
I don't recall anything in my pilot training/testing requiring me to demonstrate the ability to compute a CG and BEW following a properly altered conditional change to an aircraft. But I clearly recall them in the A&P written and oral and practical exams. Agreed the last two are anticdotal arguments for sure.

Steve

Perzactly! The TCDS shows original 6:00 tires weighing 18 lbs. 7:00 tires add +1 lb to that at the same station, and 8:00 tires add +10 lbs. Even though the TCDS shows these alternate tire sizes as approved for installation, the actual change requires a Form 337 because it changes the wt and bal of the aircraft. It therefore is not "preventive mx" and must be performed/supervised by an A&P with Inspection Authorization (IA). The alteration may not be performed by the owner/pilot. (However, once so altered, the pilot may make replacements of same-sized tires as are logged onto the aircraft.)

[jrenwick]

George,

Where does the FAA say that an alteration that changes the W&B requires a 337? If you change equipment to something that is listed in the TCDS, isn't that a minor alteration? The TCDS normally even gives you the arm and weight of each approved item as an aid in updating the W&B.

For example, when my J3's A65 engine was swapped for a C90, it required only a logbook entry, because the C90 is listed as an approved engine for a J3C-65 in the TCDS. The IA who did it also updated the weight & balance sheet to reflect the new empty weight and CG location. (There was a 337 for a change to the carb heat that was required for the C90, but no 337 for the engine swap that caused the W&B change.)

[GAHorn]

George,

Where does the FAA say that an alteration that changes the W&B requires a 337? If you change equipment to something that is listed in the TCDS, isn't that a minor alteration? The TCDS normally even gives you the arm and weight of each approved item as an aid in updating the W&B.

For example, when my J3's A65 engine was swapped for a C90, it required only a logbook entry, because the C90 is listed as an approved engine for a J3C-65 in the TCDS. The IA who did it also updated the weight & balance sheet to reflect the new empty weight and CG location. (There was a 337 for a change to the carb heat that was required for the C90, but no 337 for the engine swap that caused the W&B change.)

The discussion up to this point has described what constitutes a major repair or alteration. (Appdx A) Any repair/alteration that changes the aircraft wt/bal other than negligibly, is a major alteration.
Although the basis of approval for installation of the various items found in the TCDS is that certificate.... such alterations change the wt/bal if it is so noted in that certificate. Therefore such changes must be recorded and reported as required by:


FAR 43.9 Content, form, and disposition of maintenance, preventive maintenance, rebuilding, and alteration records (except inspections performed in accordance with part 91, part 125, §135.411(a)(1), and §135.419 of this chapter).
(a) Maintenance record entries. Except as provided in paragraphs (b) and (c) of this section, each person who maintains, performs preventive maintenance, rebuilds, or alters an aircraft, airframe, aircraft engine, propeller, appliance, or component part shall make an entry in the maintenance record of that equipment containing the following information: ...
(d) In addition to the entry required by paragraph (a) of this section, major repairs and major alterations shall be entered on a form, and the form disposed of, in the manner prescribed in appendix B, by the person performing the work. ...

Appendix B to Part 43—Recording of Major Repairs and Major Alterations
(a) Except as provided in paragraphs (b), (c), and (d) of this appendix, each person performing a major repair or major alteration shall—

(1) Execute FAA Form 337 at least in duplicate;

(2) Give a signed copy of that form to the aircraft owner; and

(3) Forward a copy of that form to the FAA Aircraft Registration Branch in Oklahoma City, Oklahoma, within 48 hours after the aircraft, airframe, aircraft engine, propeller, or appliance is approved for return to service.

John, are you certain that the Form 337 used to document the change to the carb does not also document the engine change? Although the definition of major alteration/repair does not specify engine changes to an alternately approved engine...such change, if it makes a wt/bal change, becomes a major alteration and requires a Form 337. If your IA documented that a wt/bal change occured, then he should have submitted a Form 337 for that change. IMHO

[jrenwick]

George,

Everything you're saying hangs on the assertion that any modification that alters the weight & balance is a major alteration. So what I was asking was, what wording in the FARs says this? I don't find this meaning in 43 Appendix A(a)(xi), which has been quoted before in this thread:

(xi) Changes to the empty weight or empty balance which result in an increase in the maximum certificated weight or center of gravity limits of the aircraft.

I read this to mean that a modification that changes the W&B limits as given in the TCDS would be major. For example, a kit with an STC that increases the gross weight of the aircraft. Some of these add a single piece of metal somewhere, so they might look like minor alterations, but this clause ensures they're not.

Is there another place in the FARs that says altering the empty weight of the aircraft without changing the limits constitutes a major alteration?

(Also, I can't see anything in part 43, Appendix A, (a)(1) or (a)(2) that would make an engine swap onto the same mounts a major alteration if the new engine is approved equipment. And no, the 337 I have only talks about the carb heat change -- it doesn't describe the engine upgrade. The engine swap is described on a page of the logbook.)

[skippy2]

Now I can see that I am not alone being confused!
I have to agree with Bruce that this is not a major alteration because it does not fit the argument "Changes to the empty weight or empty balance which result in an increase in the maximum certificated weight or center of gravity limits of the aircraft." The key here is changes that RESULT in an INCREASE to the CG limits or MAX weight are considered major alterations. It does not say CG or weight, it is CG limits or maximum weight.
BTW I appreciate the discussion over the topic.

[170C]

I don't have anything to add to the "what is correct or not" being disucssed, although it is interesting. When you folks get it worked out, somebody give the straight skinny on whether or not I have to have an A&P or AI do a 337 or otherwise everytime I take my back seat out or reinstall it and then go flying. This occurs quiet often in my plane. I'd sure hate to have to run down one of these guys every time I stuck the seat back in to accomodate a 3rd passenger or when after that ride/trip I pulled the seat back out to accomodate camping or vacation items.

Inquiring minds want to know

[Bruce Fenstermacher]

George in all of my posts I pasted the exact FAR word for word as you did.

True in my comments braking down the sentence I did add the extra word "certificated".

I agree with John and can not believe George, that the three of us are reading the same sentence. Oh that's right it's a FAR. no wonder we see it different.

Seriously. I read this line to mean that it only takes effect when the modification would seek to increase the maximum certificated weight or change the Center of gravity limits that have been set.

This would be hard to do on a Cessna without the need for a 337 just for the modification itself but not so on other aircraft and here is on example.

Piper J3 Cubs were certified at various weight limits over the years. Eventually it was 1220 lbs. The mods that allowed the heavier max weight were to the landing gear and to the fuselage mounting points.

After the mods were developed all gear made from that point on had the updated mods. Installing the updated gear say as a replacement for the old is a minor repair in fact no different that replacing a worn part with a new part anywhere else.

Doing so did not raise the certified maximum weight from the lower weight to which the airplane was certified, to the higher weight until a 337 is executed recording the change. Because a gross weight increase is sought, under 43.13 App A (a)(1)(xi) a 337 is necessary.

If you are buying a Cub this is one of those details you need to check to know what your buying.

[lowNslow]

(xi) Changes to the empty weight or empty balance which result in an increase in the maximum certificated weight or center of gravity limits of the aircraft.

I have to agree with Bruce. As long as you are not changing the MAXIMUM certificated weight (2200lbs. for our 170s) and center of gravity LIMITS (nothing here changes by removing the rear seat) it is not a major alteration. All you have changed are the EMPTY weight and CG. All the owner would need is a corrected Weight & Balance on which to compute takeoff weight (not to exceed the 2200lb LIMIT) and that the CG is within the LIMITS (still the same).

According to the "FAA -H-8083-1A, Aircraft Weight and Balance Handbook":

"Equipment List
A typical comprehensive equipment list is shown in Figure
2-22 on pages 2-12 and 2-13. The FAA considers addition
or removal of equipment included in this list to be a minor
alteration. The weights and arms are included with the
items in the equipment list, and these minor alterations
can be done and the aircraft approved for return to service
by an appropriately rated aircraft mechanic or repairman.
The only documentation required is an entry in the aircraft
maintenance records and the appropriate change to the
weight and balance record in the POH/AFM."

If you go equipment list cited above it shows the front and rear seats.

[steve grewing]

The FAA ASI was not at the airport today while I was there. Maybe next weekend.
Based on options in the TCDS, the permanent removal of wheel pants, and replacing 6.00 tires with 8.00 tires would be minor alterations to me. A&P logbook entry along with a weight and balance update are all I would require on my plane.
Steve

[bradbrady]

In other words, removing the rear seat to reupholster it (and subsequently reinstall it) is preventive mx and may be performed by the owner/pilot. But removal of the seat, not intending to reinstall it for flight, is not preventive mx and may not be done by the owner/pilot.

Bruce, George hit the crux of the situation on the head! Also (right now I don't know where to find it) any change over 2% of gross should have a 337 with the work done. (we know what that in tales).
brad