Rear Seat Removal

[jrenwick]

...Appendix A(a)(xi) says:
"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'm having trouble imagining how a change to the empty W&B, by itself, could result in an increase in the max weight or C.G. limits. Can anyone give an example? I know there are mods that alter an aircraft's W&B limits -- for instance, putting a J3 on floats increases its maximum gross weight. There are gross weight increase kits for many aircraft types, such as Swifts and Super Cubs, that I'm aware of. But those two examples don't change the empty W&B in any significant way. I can't really make any sense out of this clause, and George's proposed interpretations seem odd, contrived and implausible to me.

If I were a dead horse, I wouldn't care if I was being beaten! I'd like this conundrum cleared up.

John

[voorheesh]

I have two questions for Brady: You are saying that removal of the rear seat and return to service is an alteration that requires a mechanic. You may be right, but would you tell us if it is a major alteration or a minor alteration. If you think it is a major alteration could you tell us what specific condition makes it so. What specific sentence in 43 Appendix A or Part 1 makes it a major alteration?? If a private pilot decides, for whatever reason, to remove his rear seat and then replace it and return his Cessna 170 to service, can that be accomplished as "preventative Mx? This horse is still alive!

[GAHorn]

Well, I must admit that I never dreamed what I thought was a clear example of how a sentence might be construed...could be so MIS-construed.

Here's what I wrote (with a little added emphasis for those of you who do not see/read/understand the word "OR":

"The present FAR description of major alteration supported by Appdx A, (a) (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") could also be interpreted as encompassing three distinct types of weight and balance changes:
1. Changes to the empty weight.
<OR>
2. Changes to the empty balance which result in an increase in the maximum certificated weight.
<OR>
3. Changes to the center of gravity limits of the aircraft."

voorheesh, those are pretty strong words considering the sources of my information. There is no problem with a pilot removing a seat.... as long as he puts it back into the airplane before it's operated.... which is known as "replacing" a seat...EXACTLY and LITERALLY as the FAR states.

[jrenwick]

George,

You've taken the clause (xi) apart, but you've added "changes to the" in a couple of places in a way that changes the syntax and meaning of the clause. I really can't read it to mean all those possible things.

But I am still mystified as to how a change to the empty W&B, by itself, can change the certificated W&B limits, so as such, I can't make sense out of the clause as I understand it, either.

Best Regards,

John

[voorheesh]

George, again I respectfully disagree. The language you quote in the appendix relates to changes that "increase" the certificated weight or center of gravity limits only. There is no room for interpretation in that language. It says what it says. Removal of a seat in a 170 does not result in an increase in the maximum certificated weight and it does not affect the center of gravity limits so that part of Appendix A simply does not apply to this conversation. Do you remember the discussion of removal/disabling of the parking brake which you stated was a minor alteration requiring a logbook entry. Can you tell us the difference between removing the parking brake mechanism and removing the rear seat? Could you point out where in the C-170 TCDS that the rear seat is mentioned? If you are worried about the 2 FSDOs who don't agree with what I am saying, this would not be the first time an FAA office didn't exactly have their ducks in a row. I believe they will be reviewing their positions in the future and they may very well be correct that it is an "alteration". It is just not a major alteration. This is not about "interpretation". This is about showing us a specific rule that unequivacably supports your position. I do not believe that the FAA pursues enforcement cases based on "possible interpretations". Maybe the IRS does. I appologize for any strong words and I hope this discussion remains educational.

[Brad Brady]

I have two questions for Brady: You are saying that removal of the rear seat and return to service is an alteration that requires a mechanic. You may be right, but would you tell us if it is a major alteration or a minor alteration. If you think it is a major alteration could you tell us what specific condition makes it so. What specific sentence in 43 Appendix A or Part 1 makes it a major alteration?? If a private pilot decides, for whatever reason, to remove his rear seat and then replace it and return his Cessna 170 to service, can that be accomplished as "preventative Mx? This horse is still alive!

I don't know what happened to my last post.....about an hour ago.....But now I need to reread what was posted....and as far as I know, I think that what I was trying to get accost was misinterpreted.....The permanent removal of any seat is a major alteration....needing a 337.....any thing else including helping me with an annual or finding a broken seat can be fixed by the owner.....under part 43

[GAHorn]

Ok, folks...I am now going to use some CAPITAL letters to re-EMPHASISE what some of you... including you voorheesh... seem to forget AGAIN AND AGAIN! (I am getting tired of some of you crediting me or transferring the FAA-FSDO opinion to me. This has happened several times now in this discussion thread.)

Unfortunately, George is just plain wrong here. ....

(It is not correct to lay fault upon me...when all I did was point out how poor syntax may be the cause of others incorrect interpretation of the rule. That rule is poorly written and I merely pointed it out.)

As for those who continually lay what they believe to be an incorrect interpretation upon ME...This is NOT MY OPINION. This is the FAA OPINION IN SAN ANTONIO, TEXAS and FT. Worth Texas, and apparently LITTLE ROCK, ARK. and perhaps others !! GET IT? HUH?? (shouting at you guys now: ) GET IT??? I am merely reporting their position and re-telling their explanations as to how they arrived at those positions.

Voorheesh: Those FSDO's apparently interpret the rule LITERALLY when they read the word "replacing". (and voorheesh, you are someone who has on prior occasions suggested that FAR's be read plainly....and I do understand it when those FSDO's want to read that word "replacing" as being pretty PLAIN)....
It's some of you guys out there on the left-coast who seem to think that "replace" actually means something else such as "remove" or "substitute" or "install". I don't have that particular version of Webster's at my disposal and it doesn't seem to be at the bookstore either.

... Can you tell us the difference between removing the parking brake mechanism and removing the rear seat? Could you point out where in the C-170 TCDS that the rear seat is mentioned? ....

Here we go again... it's been said before, but I'll do it yet again: Pull out the TCDS.
READ the DESCRIPTION of the airplane, where on page 2 it states:

"No. of Seats 4 (2 at +36), (2 at +70)"

It doesn't get any plainer than that.

Now, it's your turn. Show me where the parking brake is mentioned in the TCDS.

Here's a copy:

A-799 Rev. 54.pdf

I agree with those FSDO's in TX and AR only in the actual wording used in that rule. It certainly does say "REPLACING". I have repeatedly....REPEATEDLY... (but some of you are either disregarding the several times I've stated that here...or you are just recently joining the conversation without reading the entire thread...) I have repeatedly pointed out that in my personal opinion the removal of the rear seat SHOULD be a minor matter and pilots should be allowed to remove the seat and operate with it removed. The problem is...that's not what the rule says.

Now... as for the recent little side-show regarding para (xi): If you guys will GO BACK and RE-READ what I originally posted.... you will see that I SPECIFICALLY said that there was a POSSIBLE error in SYNTAX and that SOME folks MAY read that paragraph to mean three different conditions MAY apply that would make the removal of the seat a major alteration. That was not an attempt by me to alter the wording in the rule...it was merely pointing out that the sentence DOES use the word "or" between each of the conditions it claims affects the level of alteration.

And AGAIN... this is only a discussion among friends who are desireous of getting FAA to come up with a uniform interpretation of this matter. I invite anyone and everyone to provide a link to their local FSDO to this discussion and invite them to pursue the question with FAA-OKC.

Meanwhile, when a participant at these forums ask the question "what is necessary to remove the rear seat"... it is NOT CORRECT to advise them to simply do so and make a note of it in their logs until ALL FSDO's interpret the rule in the same way. As long as SOME FAA types think it's a violation to remove it... then it's necessary to comply with their interpretation if you wish to avoid further trouble. And that's the way I will continue to advise folks until a uniform/universally-agreeable interpretation is arrived at by FAA.
What you do with that information is entirely up to you.

[voorheesh]

George, I obviously rubbed you the wrong way and I did not mean to do that. I read your posts and believed that you had the same opinion as the FAA offices you quoted. I was trying to challenge that and see if I could get you to see it in a different way. I was thinking you might take a few of the questions back to those guys for "clarification". As you said, it is all among friends. The FAA inspectors I know and spoke with out here on the "left" coast told me they would contact their compatriots at San Antonio and see if they could get on the same page. Interestingly enough, they did not come right out and say the Texas guys were "incorrect". They want to listen to their position and are open to changing their opinions if they are presented with valid reasons to do so. I think this is an important question for the owners of our type of airplane and I hope we can get an intelligent answer someday. In the meanwhile, my best wishes to everyone for good holidays and a happy new year.

[GAHorn]

OH, no no no.... I am not rubbed the wrong way, and I"m not the least offended.... I just wanted to overcome any deficiencies of the written word to eliminate any misunderstanding, so I restated my thoughts in an emphasized manner. You and I are friends and will remain so. No harm no foul.

Merry Christmas everyone!

[Bruce Fenstermacher]

George, I thought you were tearing that sentence apart not simply an example of how one might. I stand corrected. BTW I have had this discussion with a local IA who presented it to me. He read the sentence as you suggested. Took me about 4 hours of discussion till the light bulb went off and he slowly changed his position. It is this kind of discussion that is often necessary to sway at FAA guy. Unfortunately before that amount of time can take place the inspectors have swarmed back to the hive for reindoctrination.

John, I'll give four examples how one might propose a change to the max gross or wider limits to the CG envelope.

1. Someone comes up with and aerodynamic change which adds no weight such as VGs,fairings, reshaping an airfoil that would now allow the aircraft to be certified with a wider CG than before. This would be a major alteration under this FAR.

2. There are parts substitutions where the weight of the parts removed equals the parts installed and so no increase in weight but the new parts are structurally stronger and so an increase in max weight is proposed. This would be a major alteration under this FAR.

3. The J3 is actually a good example. Early J3s have a lower max weight than later serial numbers because the landing gear could not support the landing weight. A change to the gear design to include tubing thickness and small gussets allowed a high landing weight. The change in neglegable weight wise. This particular modification of the gear for the J3 was a factory mod and is approved through changes in the TCDS. But it requires a 337 to accomplish because under this FAR it is a major alteration. Good new is it is approved by the TCDS and needs no further thought on the inspectors part.

4. Someone, perhaps from Texas or maybe the left coast but certainly never from the east, decides that because other models of virtually the same aircraft have a higher gross weight that they can simply apply the higher gross weight to their model as a minor alteration. After all it's only a paperwork exercise right? Wrong under this FAR it is a major alteration and must come under higher scrutiny.

A good example of this in the Piper PA22-108 Colt sold from 1960 o 1963. it is the same exact airframe as the earlier PA22 but was sold with no back seat, a 108hp Lycoming engine and a lower gross weight, to compete in the pilot training market. Today it is popular to power a Colt with the 150 hp Lycoming, which requires it's own approval. Once done you would have the exact airframe and power plant as the PA22 put not the gross weight of the PA22. To increase the gross weight at this point would require an approval as a major alteration.

[wingnut]

Where are the IAs on this forum??

I have enough gray hairs to return a 170 to service with back seat removed. A change to an aircraft basic type design is either major or minor. Removing a seat does not fit the major alteration definition in FAR1.1 nor Appendix A anywhere in FAR.43.
Preventive maintenance clearing expresses that a pilot has the credentials necessary to remove a seat and reinstall a seat. And Appendix A (a)(xi) clearly expresses changes to the gross weight or CG LIMITS and NOT "any" change to either. This is a minor alteration of the aircrafts type design and would require a log book entry, weight and balance and equipment list addendum of which a pilot would be permitted to do.

[lowNslow]

Here is the position of the Northwest Moutain Region which covers all FSDO in OR ID MT UT WA WY and CO :

d. Weight and Balance. Part 43, Appendix A(a)(xi), is definitive here. If an alteration results in an increase
in the maximum certificated weight or center of gravity limits of the aircraft, the effect is appreciable and
the alteration is major. If the alteration does not result in the weight or center of gravity limitations being
exceeded, or the mass distribution being changed, then it is a minor alteration with regard to weight and
balance. Mass distribution changes, such as addition of tip tanks or replacement of an engine with a
heavier engine, constitute mass distribution changes requiring engineering evaluation, even if maximum
weight limits are not exceeded.

(This is from an document titled "Guide to Aircraft Alterations" available here. Good read if your interested in this stuff.)

As far as the seating arrangement, the FAAs own Handbook uses the example of a 182 which is certified as a 4 place aircraft as a minor alteration. If, George, your opinion is that removing the seat is a violation of the TCDS, than I assume you DO have a field approval (not just an IA signoff) for that second wt. & bal. sheet you carry?

[wingnut]

THANK YOU lowNslow!

When I presented my question to the LIT FSDO, I ask if there were any publications or AC's that might offer some guidance on this issue. Apparently, they were in a hurry and shot from the hip, which unfortunately has become more and more typical the last few years as our "gray hairs" retire and are replaced with large headed greenhorns that had parents whom were closely related.

[jrenwick]

Hi Bruce,
Thanks, yes, I'm aware of mods that change the maximum gross weight and/or CG limits, and I mentioned a couple of examples myself. I was confused in my interpretation of 43A(a)(xi), and I now understand that the "changes" it refers to are really changes to the empty W&B information as given in the AFM or TCDS, as the result of any mod that alters the W&B limits. Obviously it makes sense that a mod that does that is a major alteration. I was never in question about that.

Thanks!

John

[GAHorn]

Let's be clear with regard to wt/bal changes.... just because a mod does not change the gross wt or CG limits ... does not make it a minor alteration. That is only ONE condition which might affect the determination.

Karl, I understand what you are saying... but again, I want to make this clear... this is NOT MY opinion. And no, the 337 does not have Block 3 signed. SAT FSDO says that the TCDS provides for 2PCLM therefore no field approval (block 3 approval) is required....but the removal of the seat alters the basic configuration from original equipment and Form 337 therefore is required.