CG Limits

[jiott]

This is probably a question for the Kitfox factory (maybe John will chime in). The W&B worksheets that come with the SS7 kit as well as the spreadsheet that is available on the Kitfox website show the max allowable aft CG to be 16.00". This number is apparently independent of gross weight. However, when I was taking my training with Stick & Rudder in their SLSA, the POH showed an allowable CG envelope that was not so simple; it showed a max aft CG of 16.00" at 1320 lbs, but it then slanted back to 14.00" at 1050 lbs. Which is correct?

The main reason I ask is that I recently loaded up my SS7 for a camping trip with me alone (no passenger) but lots of gear in the baggage compartment. My weight was1250 lbs with an aft CG of 16.0". It did not feel unsafe in flight, but definitely felt tail heavy in the landing flare. According to the SLSA POH I should have limited the aft CG to 15.5". In my case here it is probably no big deal, but I could see that with a very lightweight pilot flying solo with lots of gear in the baggage area the discrepancies between these two aft CG envelopes could become quite large. Some clarification would be nice.

[t j]

My kitfox is a 4, but anyhow here's my story on weight and balance.

Everything Put in the plane moves the CG back. The baggage has a weight limit of 40 pounds. I load 40 pounds in the baggage then people and fuel to get a maximum gross weight and maximum aft CG. (15.8 inches...within limits for both the max aft limit and the Center of gravity Moment Envelope graph.)

As fuel is burned off in the wing tanks the CG moves forward but stays above the slanting line (bottom side) on the Center of Gravity Moment Envelope Graph so stays inside the box. I don't know if I was just lucky of if that is true for all kitfox models.

Does your baggage compartment have a maximum weight limit?

[jtpitkin06]

It is important not to confuse requirements for Special Light-Sport Aircraft certification with experimental aircraft requirements.
Manufacturers of S-LSA must meet very strict flight testing requirements. There is a specific flight testing schedule that must be followed. Part of the certification is flight at different weight and CG locations. If the LSA manufacturer is only able to load the airplane to a CG of 14.0 inches at 1050 pounds, then that is the maximum that will be shown on the weight and balance documents. It is easier to achieve an aft CG at heavier weights so the aft CG may have been demonstrated at a different location. The CG envelop may look quite different on a S-LSA when compared to the envelop on an Experimental aircraft.


As a builder of an Experimental LSA or Experimental – Amateur Built, you may put the aft CG wherever you desire but you make entry in the log book that you flight tested it at XXXX pounds and a CG location of XX inches with no adverse characteristics.



The answer is; yes, it is safe to fly your Model 7 at lighter weights with a CG of 16.0 It will obviously feel a little lighter on the controls with an aft CG.

[jiott]

Thanks for the reply John.
TJ, my baggage compartment was full but the total baggage weight was about 50 lbs-far below the max of 150 lbs. I don't see how you could ever get even close to the 150 lb limit without exceeding the aft CG limit of 16.0".

[Paul Z]

I have found the same issue, you need to pull the heavy stuff forward in the baggage area, and all the light stuff to the back. When I flew to oshkosh this definately helped.

[SWeidemann]

I'm asking advice about how to handle the small additional weight of adding a cabin heater and a couple of thermostats. I installed the coolant heater kit and at the same time I am changing engines (from a runout 912-ULS to a new one), with the addition of an oil and coolant thermostat. Is there any reason to do any more computations, or is a log book entry satisfactory?

Thanks much, Skot

[Danzer1]

Skot,

You have a couple of issues to deal with.

1st, if I recall, you bought the aircraft used. Did you ever obtain a repairmans certificate for it? If so, you can sign off on the changes. If not you will need an AP to sign off. Once you have that sorted out -

2nd, you need to read the operating limitations in your Airworthiness Certificate. Likely it is worded ambiguously enough to prompt a call to your local FSDO for clarification.

If they consider the changes substantial enough (likely) they will also (likely) require a new condition inspection and a new phase one flight testing for a certain number of hours. With a new condition inspection a new weight and balance could be required.

Changing an engine (even of same type) and adding accessories that weren't there before - will (likely) prompt any FSDO to require the above, but as we know, they all don't all interpret what is written the same, so it is best to check with them first.

Greg

[N981MS]

Skot,
As I understand it, anyone can work on an experimental. Change the engine to a turboprop. Wing airfoil. Make it a biplane. Put in a heater. Anything. No need for an A&P sign off.

The repairman's certificate allows the builder to do the annual condition inspection.

Crazy eh?

I do not think your weight and balance issues require FSDO involvement unless you are changing the current registered cg range. If you are just updating your empty weight and empty cg, I think you are OK.

At least one DAR I know says things that change flight characteristics are what requires going back in to phase one for a duration determined by the FSDO. ie change the prop. Change Engine type. Change gross weight.

I am not a DAR and did not stay at a Holiday Inn last night so YMMV.

[Danzer1]

Max,


As I understand it, anyone can work on an experimental. Change the engine to a turboprop. Wing airfoil. Make it a biplane. Put in a heater. Anything. No need for an A&P sign off.

The repairman's certificate allows the builder to do the annual condition inspection.For clarity - I did not say he couldn't do the work himself - I was intending to refer to signing off the annual condition inspection as you have mentioned.

If he does not have the repairmans certificate - he then needs an A&P to sign off on the annual and that would include all changes made since the last annual. The conditions of the airworthiness certificate usually mention logging modifications and I would expect any good A&P to notice the changes made in review of the logs and therefore include them in the annual inspection.


At least one DAR I know says things that change flight characteristics are what requires going back in to phase one for a duration determined by the FSDO. ie change the prop. Change Engine type. Change gross weight.I agree, so the question would be for the DAR/FSDO - does adding an oil cooler, thermostats, cabin heater, piping, fan, etc - change the CG and the gross weight and distribution and hence flight characteristics? Would be up to his local DAR/FSDO to clarify - as mentioned.

Skott also mentioned in previous threads/posts, adding strut fairings, fuel pump, new prop blades, replacing engine and mount. So again, up to the DAR/FSDO as to whether any of this would change not only the weight, but also the flight characteristics of the aircraft.

Still think it's best to check (FWIW).

Greg

[jrevens]

I know that practically everyone reading this knows that if it's licensed as experimental amateur-built (EAB), you can't get a Repairman's Certificate unless you're the builder.

If you bought the airplane, it would be a good idea for your own peace of mind & safety to do a weight & balance computation regardless of any changes, and especially if doing something like an engine change, IMHO. The small amount of time & effort is worthwhile.

[SWeidemann]

Guys,

For a local opinion from an experienced builder friend of mine, who is also a long time EAA Chapter Technical Counselor for two chapters, I called him today.

I'm going with his advice that new inspections by the Feds followed by designated flight testing would only be prudent for major changes that will affect the flight characteristics. Small changes that change or add (small) weight distribution should be recorded as far as what they weigh, where the changes are in the airframe, and be included in a re-done weight and balance, or better yet, an actual re-weighing to figure the flight range. A new engine, same model as the one removed has no significance.

So far the only change (for weight & balance) I have made is the cabin heater kit. I will probably add the thermostats as well. My friend has a set of scales, so I may be re-weighing as well.

Since this EAB plane was built by another, I will be getting my Condition Inspection (not an Annual) by my regular mechanic. He is aware of what I am doing. If I had a ELSA I would be taking the Rainbow repairman's certificate class. If I built a kit or something with the 51% rule I would certainly apply for my repairman's certificate for that aircraft.

Skot

[Paul Z]

An interesting article on changing from an SLSA to ESLA.
Definitely some advantages to going ESLA. I have considered doing this with my plane.

http://www.newplane.com/amd_download...0to%20ELSA.pdf

[SWeidemann]

Paul,

As the current rules stand, you could convert your Kitfox SLSA to the ELSA category, take a two day maintenance course, and then be qualified to legally maintain your plane (and sign off the annual condition inspections). Sounds wonderful to me, however I would want to follow up what (if anything) is happening with the Craig Holmes FAA draft proposing restrictions. I have found old information about these ideas to change the regulations (from around March, 2014), but nothing since.

Skot

[Danzer1]

Skot,


As the current rules stand, you could convert your Kitfox SLSA to the ELSA category, take a two day maintenance course, and then be qualified to legally maintain your plane (and sign off the annual condition inspections).

Sorry, but that's not quite right. The 16 hours is for an inspection training course and only gets you the "Inspection Rating" of an LSA Repairmans Certificate. This only allows the holder to sign off on the annual condition inspection of his own ELSA.

To get the "Maintenance Rating" of an LSA Repairmans Certificate you need 120 hours of FAA approved instruction for that rating.

Full rule here: http://fsims.faa.gov/wdocs/8900.1/v05%20airman%20cert/chapter%2005/05_005_006rev1.htm

Greg

[SWeidemann]

Greg,

So I can work on my own E-LSA and sign off the annual Condition Inspection with the 16 hour course. Right? That's the advantage I can see, and that is a big one since as I know arranging to get my plane to the mechanic's shop when he can do the Inspection is often an exercise in juggling schedules and going when the weather is good (if you fly it to his shop).

On my Certified aircraft (not Experimental) as an owner pilot (with no special ratings other than being the owner and pilot) I can already do all the important things. I can take off cowls, grease wheels, adjust brakes, change oil and so on without any "illegal" behavior. IF I get into a gray area (of maintenance) that may not be included in my pilot/owner privileges I can still do it with supervision and approval by my favorite A&P, and of course he has the Inspection Authorization to sign off my owner assisted annuals.

Skot

[Danzer1]

Skot,

The same applies as to certified aircraft. With an "Inspection Rating" you can only do "preventative maintenance" - just like certified.

For any other "maintenance" you would need an A&P to sign off or hold the "Maintenance Rating".

FAA definition of "maintenance":

Maintenance. Inspection, overhaul, repair, preservation, and the replacement of parts, but excludes preventive maintenance.

Greg

[HighWing]

From reading this it appears there are lots of apparent approaches to the "legalities"

I would like to post a little documented "facts" as I would call them. This is from my:


Experimantal Operating Limitations
Operating Amateur Build Aircraft
Phase 2 document
Operations Outside the Assigned Test Area


The paragraph below is exactly the same wording as in the Phase 1 Document.


Operations in the Assigned Flight Test Area


Paragraph:

(19) After incorporating a major change as described in 14 CFR & 21.93. the aircraft owner is required to reestablish compliance with 14CFR & 91.319(b) and notify the geographically responsible FSDO of the location of the proposed test area. The aircraft owner must obtain concurrence from the FSDO as to the suitability of the test area. If the major change includes installing a different type of engine(reciprocating or turbine) or a change of a fixed-pitch from or to a controllable propeller, the aircraft owner must fill out a revised FAA form 8130-6 to update the aircraft file in the FAA Aircraft Registration Branch. All operations must be conducted under day VFR conditions in a sparsely populated area. The aircraft must remain in flight test for a minimum of 5 hours. The FSDO may require additional time (more than 5 hours) depending on the extent of the modification. Persons nonessential to the flight must not be carried. The aircraft owner must make a detailed logbook and maintenance records entry describing the changes before the test flight. Following satisfactory completion 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 14CFR &91.319(b), must be recorded in the aircraft records with the following, or 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 characteristics or design features and is safe for operation. The following aircraft operating data has been demonstrated during the flight testing: Vso_________, Vx_______,
and Vy________, and the weight_______, and CG location _______ at which they were obtained."

Notice all reference to the person performing the modification or submitting data to the FAA is referred to as the "Owner" or the "Pilot". There is no reference to any need for a certificated person to be involved either in the major modification or in the log book entry or in the notification of the FSDO. Also notice that in the occasion of an engine or prop type change the notification is made to the Registration Branch to "update the file".

I am not one to ignore the regs or prudent behavior especially since I had to submit all my records after our "hard landing" destroyed our first Kitfox, but this seems all pretty simple and straightforward. Also keep in mind that this document was presented to me and signed by Richard T Dilbeck, Aviation Safety Inspector, Sacramento FSDO.

With regard to the hard landing. The ultimate enforcer, in my opinion, is your insurance company. My understanding is that if you are in violation of the FARs, your insurance company is likely to say, "Hey, thanks for the premiums all these years, see you later."

[Paul Z]

:D
Paul,

As the current rules stand, you could convert your Kitfox SLSA to the ELSA category, take a two day maintenance course, and then be qualified to legally maintain your plane (and sign off the annual condition inspections). Sounds wonderful to me, however I would want to follow up what (if anything) is happening with the Craig Holmes FAA draft proposing restrictions. I have found old information about these ideas to change the regulations (from around March, 2014), but nothing since.

Skot

I am taking the 120 hour Rainbow Aviation class in January, Paul Leadabrand recommended taking the class, he took it so he maintains his own fleet. He does an excellent job. With the Light Sport Repairman Certification, I will be able to do my own work. So that will resolve one issue. However, I am still considering converting the Kitfox SLSA to the ELSA, making changes is a real painful process, requiring a long round trip flight.

[Danzer1]

Lowell,

If you are referring to the 1st part of this thread - I disagree.

Nowhere in what you posted does it say the owner or pilot can make the modification, alteration or repair. It essentially says - the owner is responsible for the proper documentation of it.

Your post further states in 3 places, it all has to comply with CFR 14. CFR 14 part 43.7 only allows a a private pilot to return an aircraft to service after preventative maintenance - for everything else you either need to be an A&P or hold the Repairmans Certificate. As pertains to EAB in this scenario.

So with EAB, he could do the work under the supervision of an A&P, but an A&P would have to sign off to return the aircraft to service. As he stated he bought the aircraft used, he does not hold the Repairmans Certificate.

The "facts" of 43.7 are here: http://www.ecfr.gov/cgi-bin/text-idx?SID=da0f806fb3dd3994ced38affbd8bb992&node=se14.1.43_17&rgn=div8

If you are referring to the last part of the thread - it doesn't apply at all as we were discussing SLSA converted to ELSA not EAB.

[Av8r3400]

Owning an E-LSA registered aircraft and having taken the 16 hour class, here is what I was told to this specific question.

My light sport repairman's license, specified to my aircraft only, allows me to do any and all maintenance and modifications within the instruction of the operating limitations (eg notifying the FAA of a major change) as I see fit. It allows me to do the annual condition inspection and sign off the aircraft as airworthy. In simpler terms this license has given me the "repairman's certificate" for this particular aircraft.

If I wanted to work on a different aircraft that I do not own, the 120 hour class is required.

[Danzer1]

Forgot to mention - 14 43.3 states who is authorized to make the changes - read particularly (d).

Facts here: http://www.ecfr.gov/cgi-bin/text-idx?SID=b59a1ff5aac3f477b24533bec96b82b4&node=se14.1.43_13&rgn=div8

And Appendix A of 14 43, defines what are major alterations, major repairs and preventative. So everything other than preventative is a "Major Change". Everything previously mentioned by Skot falls into one of the "major" categories. So to "reestablish compliance" would be required IMHO - contrary to the advice he has obtained from his TC.

Facts of Appendix A here: http://www.ecfr.gov/cgi-bin/text-idx?SID=b59a1ff5aac3f477b24533bec96b82b4&node=ap14.1.43_117.a&rgn=div9

Major changes can be other than just those that affect "flight characteristics" as was stated.

[Av8r3400]

As with all overburdensome governmental regulations, interpretation is everything.

What I stated is what the FAA designated instructor told me during the class, and was then confirmed by the FSDO that issued my "Repairman Light Sport Aircraft"* certificate.


(* As printed on the certificate card.)

[Danzer1]

Larry,

I do not know who told you that, but that is contradictory to my FAA DAR conversation - might want to double check.

You have to have the "Maintenance Rating" on your "Repairmans Certificate" to perform maintenance SLSA or ELSA. I do however agree, it does also allow you to work on other aircraft of the same class.

Also note under 5-1250 C. it changes reference to "LSA" as that section applies to both SLSA and ELSA.

If your certificate says "Inspection Rating" that is all it authorizes. Per 14, 65, Chapter 5-1250.

Here: http://fsims.faa.gov/wdocs/8900.1/v05%20airman%20cert/chapter%2005/05_005_006rev1.htm

Note, it says similar to part 65.104 which only allows EAB condition inspections. Not to be confused with 65.103 which also allows EAB maintenance.

Here: http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&node=14:2.0.1.1.4#se14.2.65_1103

Good Luck,
Greg

[kitfoxnick]

Part 43 doesn't apply to experimental.

43.1
(b) This part does not apply to—

(1) Any aircraft for which the FAA has issued an experimental certificate, unless the FAA has previously issued a different kind of airworthiness certificate for that aircraft; or

(2) Any aircraft for which the FAA has issued an experimental certificate under the provisions of §21.191 (i)(3) of this chapter, and the aircraft was previously issued a special airworthiness certificate in the light-sport category under the provisions of §21.190 of this chapter.

(c) This part applies to all life-limited parts that are removed from a type certificated product, segregated, or controlled as provided in §43.10.

(d) This part applies to any aircraft issued a special airworthiness certificate in the light-sport category except:

(1) The repair or alteration form specified in §§43.5(b) and 43.9(d) is not required to be completed for products not produced under an FAA approval;

(2) Major repairs and major alterations for products not produced under an FAA approval are not required to be recorded in accordance with appendix B of this part; and

(3) The listing of major alterations and major repairs specified in paragraphs (a) and (b) of appendix A of this part is not applicable to products not produced under an FAA approval.

[HighWing]

Greg,
Sorry to disagree. The only thing I will apologize for is misreading the paragraph symbol and inserting the ampersand. Keep in mind that I am arguing EAB not ELSA. Below is a copy of the 2 referenced paragraphs in the FSDO issued Operating Limitations. I guess you can add other parts or paragraphs to your copy of your operating limitations when you finish your airplane, but for me, I will go with what the FAA deemed applicable. A thought on that. I don't think Mr. Dilbeck made any of this up especially for me. I tried to negotiate quite passionately for modifications to my flight test area. Mr. Dilbeck didn't have the final say. I was shown some of the correspondence between him and the director. Although he had authority over me, he was obviously under a higher authority. He toed the line.

§ 21.93 Classification of changes in type design.
(a) In addition to changes in type design specified in paragraph (b) of this section, changes in type design are classified as minor and major. A “minor change” is one that has no appreciable effect on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness of the product. All other changes are “major changes” (except as provided in paragraph (b) of this section).

§ 91.319 Aircraft having experimental certificates: Operating limitations.
(b) No person may operate an aircraft that has an experimental certificate outside of an area assigned by the Administrator until it is shown that—
(1) The aircraft is controllable throughout its normal range of speeds and throughout all the maneuvers to be executed; and
(2) The aircraft has no hazardous operating characteristics or design features.

Part 21.93 applies to all aircraft as is evident when reading the entire regulation as it relates to transport aircraft, helicopters, ag aircraft, etc.

Part 91.319 specifically applies to Experimental Amateur Built Aircraft.

I suspect in the wisdom of the FAA, if my engine, landing gear or wing swap applies to another part or paragraph in the FARs it would be mentioned in my operating limitations. There have just been too many years monitoring email lists and forums listening to thousands of guys and actually watching others and helping at times doing all sorts of things to their personally built or purchased experimental aircraft to finally at the close of 2014 to find that they had it all wrong all that time. In short an amateur built aircraft can be worked on by anyone - Preventive, routine maintenance or major repairs or alterations. The only signature required from a certificate holder is at the Annual Condition Inspection.

[Danzer1]

Lowell,

Did not ask you to apologize for anything and no need to. I suppose as Larry says -
As with all overburdensome governmental regulations, interpretation is everything.

We're talking about the government here and as I've been finding each DAR and FSDO seems to have a different take on just about everything.

So, as I suggested at the beginning of this thread - it is best to check with the DAR/FSDO that you/he will be dealing with.

Greg

[kitfoxnick]

Your post further states in 3 places, it all has to comply with CFR 14. CFR 14 part 43.7 only allows a a private pilot to return an aircraft to service after preventative maintenance - for everything else you either need to be an A&P or hold the Repairmans Certificate. As pertains to EAB in this scenario.

So with EAB, he could do the work under the supervision of an A&P, but an A&P would have to sign off to return the aircraft to service. As he stated he bought the aircraft used, he does not hold the Repairmans Certificate.

The "facts" of 43.7 are here: http://www.ecfr.gov/cgi-bin/text-idx?SID=da0f806fb3dd3994ced38affbd8bb992&node=se14.1.43_17&rgn=div8
Danzer only appendix D of part 43 applies as it is written into the operating Limitations, no other part of part 43 applies