Changing gross weight with the FAA...

[DBVZ]

Is it possible to change the weight when you change the wings, for a non-builder owner? The different wings allow higher weights when building, but how do you do it later as a non-builder owner? And if the builder can set the max gross even higher than the kit MFG suggests for a particular wing, what can a non-builder owner do if he makes a "major modification" and submits the resulting new W/B to the FSDO?

[jtpitkin06]

Yes, you can increase the gross weight as an owner. It is considered to be a major modification just as changing the wings to a different airfoil or structure.


Refer to the operating limitations. It will tell you what to do in the event of major mods. Typically, you will notify the FAA, do new weight and balance forms, and re-enter the Phase 1 flight testing. You will be assigned a flight test area and need to fly off the hours. Probably 5 hours at max. You will make the appropriate logbook entries and then you are good to go.


Not really too complicated. But it is doable.


One additional note: If you increase weight above 1320 pounds, the aircraft may NEVER go back to LSA; even if you declare a future gross weight under 1320. The rule is clear. If an aircraft has EVER been operated outside of LSA then it may never be certified or operated as LSA.
Where some people get stung is putting on an in-flight adjustable prop. That automatically bumps you out of LSA forever, even if you later take it off. If it’s in the log… it’s history.


John Pitkin
Greenville, TX

[akflyer]

On what form do you submit the "gross weight" of your aircraft to the FAA?? Just curious cause there is nothing in the FAA files on several of the planes we fly localy that states anything about a "gross weight" ?

[DBVZ]

The one I am aware of is the W/B that the DAR signs off when you submit the program letter to go into flight testing. Not sure where that goes, but it is where the CG limits and gross weight are set, or so I was told. It does not show up on the AW cert or registration. My question was about if a "major modification" and a new flight test period of 5 hours (with a new W/B for the flight test) would work to change it. Seems like it does, even for a non-builder owner, if John Pitkin is right. Makes sense to me.

The next question is if the MFG plate on the tail gets changed too. Seems like it could be a ramp check problem, though you would have a more current W/B to show.

[akflyer]

If you get ramp checked, just have your latest W/B form and you should be good to go. When the FAA inspector came down and looked at my plane due to a "lost AW cert" (the original burned up in a house fire so said the original owner) he glanced at the paperwork I had put together for the total rebuild on the plane. He never looked at nor signed off on the W/B. I dont see any reason for them to do so. Then again, different FSDO's seem to do things MUCH differently and there is no real consistancy across the states. Maybe I just got real lucky to have a very nice guy come down and check my plane out. Too bad he retired a couple months after he handed me my pink slip.

[jdmcbean]

Yes, you can increase the gross weight as an owner. It is considered to be a major modification just as changing the wings to a different airfoil or structure.
Refer to the operating limitations. It will tell you what to do in the event of major mods. Typically, you will notify the FAA, do new weight and balance forms, and re-enter the Phase 1 flight testing. You will be assigned a flight test area and need to fly off the hours. Probably 5 hours at max. You will make the appropriate logbook entries and then you are good to go.
Not really too complicated. But it is doable.



Just a reminder that while the non-builder/owner can do the maintenance it does require an A&P to sign off the work. Also, you may be asked by the FSDO to substaniate the changes. The Data plate should not be changed.. It is actually against the regulations to remove the data plate.

While a ramp check will typically only look at the documents in the aircraft or on-hand and available they can request to see all the log books and other documents. Also, if there is an incident or accident you can be assured that all the documents will most likely be looked at either by insurance, FAA or NTSB.

[DBVZ]

I flew a Kitfox V where the builder did the same. The W/B the DAR saw was 1320, but nothing on the data plate. Most builders fill it in though, so as a subsequent owner you deal with what you have. 1320 W/B on a V that was designed for 1550 is one thing. I also saw an Avid IV with 1320 on the W/B the DAR saw, and 1320 on the data plate. HH wings that are usually considered 1150, though often increased to 1200 or 1250 with floats just because.

[MotReklaw]

EAA has an excellent kit for experimental home built aircraft that guides one through the process of registration. The instructions say to just enter the information required by the FAA, which does not include gross weight and the other info such as address, etc.
EAA will supply a data plate that has the information needed. I built two and didn't enter the gross weight on either. The DAR did ask me though what the gross weight was and looked at my W&B calculations.

(waiting for the weather to cool so I can get back to the hangar and get the wings hung on my SS7)......

[DBVZ]

I have been looking for Avid wing loading information. Help me understand the G-loading question. In looking for load ratings for the different wings used on the Avid Mk IV, I think I have this right:

Gross Weight G-load Wing Span

Speedwing: 1050 +6/-3 23' 11.5"

Heavy Hauler: 1150 +4.4/-2.2 29' 10.5"


My question is, if the Speedwing is +6/-3 at 1050, how does that change with increased weight? My simple calculation is 6 X 1050 = 6300 pounds loading. 6300/4.4 = 1432. So why not set the max gross at 1432? Or set it at 1320, and have a G-load of 4.77? If someone can direct me to authoritative load ratings for the other wings, I would appreciate it. Thanks.

[jtpitkin06]

Refer to AC 65-32.
Here's an excerpt that shows what to do for a major modification to an E-LSA. The E-AB procedure is pretty much the same.

As pointed out, if you are not the builder, you can do the work but you'll need an A&P or the original repairman certificate holder to sign it off. You can do the flight testing yourself.


"Major Alterations. Because the aircraft is issued an ELSA certificate, a non-certificated
person may perform additional maintenance, preventive maintenance, or alterations on the
aircraft. If a major alteration, as defined by § 1.1, is performed, such as changing the engine to
another model that increases the original engine horsepower by 10 percent or more, a
maintenance record entry and a new FAA Form 8130-6, Application for Airworthiness
Certificate, must be made and sent to FAA, Aircraft Registration Branch, AFS-750. A new FAA
Form 8130-6 is required because the aircraft has been modified and is no longer the same aircraft
as identified on the original FAA Form 8130-6 in the aircraft’s file. A designated airworthiness
representative (DAR) or FAA aviation safety inspector (ASI) will review the change(s) and issue
new operating limitations for the aircraft. The new operating limitations may require the aircraft
to be put in a flight test area for a certain number of hours until the new alteration has been flight
tested and the aircraft is proven to be safe to operate within its design envelope. When the
flight-testing is complete, the test pilot should sign the aircraft off as safe-to-fly in accordance
with its operating limitations. (See Appendix 1, Figure 2.)"

[jtpitkin06]

There is more to gross weight limits than simple wing loading g limitations. A wing may be able to withstand 6 g’s at 1050 pounds without failure. However, your simple calculation doesn’t take into account the performance at weights greater than 1050. The power to weight loading may not be sufficient to allow for climb.
Simply put, you could yank on the stick and the wing won’t break. But the airplane is so heavy at 1432 pounds it can’t get above pattern altitude.
Short wings on a light aircraft can produce a speedy ship. But there’s always that pesky piper to pay.
Notice the heavy hauler gains a whopping 100 pounds in gross weight, but it takes six feet more wingspan to do it. The longer wings have a greater wing bending moment so the g limitation is lower. This tells me the Speedwing 1050 weight is near the limit of its performance. If you were to actually load the short wing to 1432 the induced drag may be so high it may not be possible to climb with just 100 hp.

John Pitkin
Greenville, TX

[DBVZ]

If I understand you correctly, it becomes a performance issue rather than a structural issue and may depend on the HP of the engine. Something that could be determined during a 5 hour flight test program as part of a weight change "major alteration"?

[t j]

There seems to be some confusion on where a specific Kitfox's maximum gross weight is documentated. Here's my take on where it can be found.

My operating limitations contain this paragraph:
"...Following satisfactorycompletion of the required number of flight hours in the flight test area,the pilot must certify in the records that the aircraft has been shown to comply with 91.319(b). Compliance with 91.319(b) must be recorded in the aircraft records with the following or a similarly worded statement. "I certify that the prescribed flight test hours have been completed and the aircraft is controllable throughout its normal range of speeds and throughout all maneuvers to be executed, has no hazardous operating characteristics or design features, and is safe for operation. The following aircraft operating data has been demonstrated during the flight testing: speeds Vso____, Vx____, and Vy____, and the weight_____ , and CG location_____ , at which they were obtained."

Now, being that V speeds and Vso by definition for an aircraft are determined during flight testing at maximum gross weight, there you have your maximum gross weight required to be recorded right there in your aircraft's log book.

[DBVZ]

The following aircraft operating data has been demonstrated during the flight testing: speeds Vso____, Vx____, and Vy____, and the weight_____ , and CG location_____ , at which they were obtained."

Now, being that V speeds and Vso by definition for an aircraft are determined during flight testing at maximum gross weight, there you have your maximum gross weight required to be recorded right there in your aircraft's log book. You would think so, and perhaps that is what the FAA intends and expects. But the Avid Mk IV I mentioned with 1320 on the data plate shows test flights were done at 1070. All signed off by the DAR with 1320 listed as max gross on the top of the official W/B, even though the most forward, aft, empty CG calculations are all at lower weights. Go figure. BTW, the Operating Limitations I saw for that plane seems to have been signed off with those items blank, for the builder to fill in. DAR not doing his job? Or builder not doing his? Or both?

Also, the Operating Limitations are not in the aircraft log book are they? Need to be carried in the aircraft, and the log books are not.

[MotReklaw]

I am confused, which is not uncommon.

I thought the DAR signed off on the plane before the flight testing so these Phase I testing items aren't even entered into the log book when the DAR signs off.

I probably misread/misunderstood this thread.

[DBVZ]

That is what the question marks are about. I have not been through this myself. If it is normal for the DAR to issue the operating limitations before flight testing starts, and for the owner to fill in the blanks on it, then it makes the process kind of suspect when 1320 shows up as max gross and it looks like the owner tested at 1070. I saw a post that said you could set max gross at 2000 if you wanted but the DAR would likely want to see your justification. When would he see it? I think the original W/B is done before the first flight, to show that the test pilot has looked at the CG and load issues. If the owner did not flight test at the recorded max gross, the V speeds will be wrong for the max gross on that W/B.

Back to the original question, if a change of max gross is a major modification requiring another 5 hours of flight test, here is what I would think that means. First, evaluate if the structure can handle more weight, or rather if a reduction on the G-load factor still gives you enough safety. Then:

1. Fly it at current max gross +50 and record the Vso, Vx, and Vy, and CG location tested at that weight. It would seem like the stall speed would be important to know for a lot of things, including keeping it LSA legal as the weight is increased toward 1320 if that is the intent. I would also want to test climb rate at about 1000 MSL and ceiling standard day, but the FAA form seems not to care about that.

2. Fly it at current max gross +100 and record the Vso, Vx, and Vy, and CG location tested at that weight.

3. Fly it at current max gross +150 and record the Vso, Vx, and Vy, and CG location tested at that weight.

4. Fly it at current max gross +200 and record the Vso, Vx, and Vy, and CG location tested at that weight.

Quit when you get either the max gross you would like, or when you get close to performance you do not like. Climb rate at or near 500 fpm, or ceiling at or near 10,000, or stall at or near 50 mph for example in a kitfox or avid you want to operate LSA. All provided you do not exceed reasonable loading for the aircraft structure. As noted earlier, for a speedwing with +6/-3 that would not be much of a problem since the wing is so short. Am I missing something?

[rogerh12]

If it helps with an example, when I upgraded my zenith 601 HDS 75 hp VW engine to a 100 HP VW engine, I informed the FAA as required by law as it counted as a major change. The FAA just had my A&P inspect the changes during the annual conditional inspection, and sighed off the work.

The FAA issued me a new pink slip, and also gave me the option of increasing the gross weight by 50 lbs on the new pink slip (though I declined as the landing gear was not modified to take the extra load). Of course, this is not exactly the procedure as outline “by the book”, but hey, the FAA can do whatever the want in these matters, yes?

They assigned me a 10 hour fly off (Note: I bought the plane from the original builder)

Hope this helps


Roger

[MotReklaw]

"....That is what the question marks are about. I have not been through this myself. If it is normal for the DAR to issue the operating limitations before flight testing starts, and for the owner to fill in the blanks on it, then it makes the process kind of suspect when 1320 shows up as max gross and it looks like the owner tested at 1070...."

Dwight,

I built two homebuilts. On both of them, the DAR ask me what the Max Gross was. I told him and he wrote it down. I showed him my W&B calculations. Then, during Phase I testing, I entered the following information in my log book concerning the above:

"I certify that the prescribed flight test hours have been completed and the aircraft is controllable throughout its normal range of speeds and throughout all maneuvers to be executed, has no hazardous operating characteristics or design features, and is safe for operation. The following aircraft operating data has been demonstrated during the flight testing: speeds Vso____, Vx____, and Vy____, and the weight_____ , and CG location_____ , at which they were obtained."

I guess I am not sure what you are talking about so I will bow out of this thread.

Best to you,

Tommy

[DBVZ]

I guess I am not sure what you are talking about so I will bow out of this thread.

Best to you,

TommyI think I misunderstood your prior post. Thanks for the information you provided.