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Back in JanuaryI mentioned a uniquely Canadian regulatory issue revolving around wing loading and weight limits. I fired an e-mail off to the TC guy in charge of this stuff, and finally heard back from him last week.

The amateur build regs in Canada specify a maximum wing loading (see AWM 549.103)- if the aircraft's wing loading is too high, then it is classified as a high performance amateur-built aircraft, and that triggers a requirement that any pilot hold an individual type rating for that aircraft. The hoops you need to jump through to get an individual type rating are aimed at type-certificated aircraft, as they require ground training, etc. They need to be liberally interpreted to allow the square-peg amateur built aircraft to fit in the round regulatory hole.

CAR Standard 421.40 lays out knowledge, experience and skill requirements that must be met to obtain an Individual Type Rating for a High Performance Aeroplane. The experience requirement is easy to meet, as it is only 200 hours total time on all aircraft types. The knowledge requirement is a bit more difficult, as it calls for ground training on the aircraft type. But, this is only a standard, not a regulation, so there is a bit of room for interpretation. My friendly TC guy recognizes that a formal RV-8 ground school does not exist, so I simply need to convince him that I know everything I need to know about the aircraft. Given that I built it, that won't be too difficult. The skill requirement is met by my friendly TC guy climbing in the back and giving me a check ride. I suspect many TC inspectors would not feel comfortable climbing in an amateur-built aircraft, but I am lucky that this guy has an open mind.

My plan is to initially declare a gross weight of 1800 lb. After the flight test phase is complete, and I can carry passengers, I will do a check ride, obtain the individual type rating for an RV-8 then file the paperwork to increase the gross weight.

I suspect that many Canadian amateur-built aircraft owners are either ignorant of the wing loading regulation, or are ignoring it. Aircraft like Harmon Rockets, some Lancairs, etc probably have declared gross weights that require the pilot have an individual type rating, but I bet many of the pilots don't have one. They may think they have slipped on past TC, but their insurer could have the last laugh, as this would give them an easy reason to deny payment if there was ever an accident.

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  • Kevin

    I have just read your thread on Doug Reeve's site regarding the TC paper restrictions on gross weight. I have been wrestling with that one for a while and using the formulae I am limited to 1896 lbs. A 2000 lbs gross would be much more useful. The discouraging part is that this rule is not uniformily applied accross this country. My cousin in BC recently did an F1 and he did not have to use the formulae. I question the validity of the formulae itself. If I had a properly sized piece of plywood I could legally have a higher gross weight. The formulae does not take the airfoil into account at all. I how we can go about getting the basic formulae looked at.

    Tom Martin

    Comment last edited on about 5 years ago by Kevin Horton
  • Hi Tom,

    One of us has screwed up this calculation somehow, as the lower wing area of the Rocket should lead to a lower max allowable weight. I hope I'm the guy who screwed up, but I don't think so.

    One thing that puzzles me is what wing area a Rocket has. It has the same wing chord as an RV-4, with less span. Van advertises a wing area of 110 sq ft, for the RV-4 with 23 ft of span, and Van's old style wing tips. What is the span of your Rocket, and what do the wing tips look like? I did a Google search, and came up with a Rocket wing area of 109 sq ft, which doesn't make sense, unless the wing chord has been increased, or Van is not reporting the correct wing area.

    What is your flap span, and what flap chord did you measure? What is your wing chord?

    I agree that this requirement is not well known, so I am not surprised that some people haven't complied with it. I also agree that is isn't obvious whether it is the "right" requirement. Someday, when things slow down (i.e. not in the next few months), I hope to do some research on the history of this requirement, and propose a change to the TC, the RAA, etc.

  • Kevin,
    Have you compared Van's published wing area to the Transport Canada Definition:

    549.103 [Maximum Take-Off Mass and Wing Loading

    (a) For the purpose of this sub-chapter:

    (1) The wing area S is defined as:

    (i) the area enclosed by the wing outline including ailerons and flaps in the retracted position, (obtained by extending the wing leading and trailing edges through nacelles and fuselage to the aircraft centre line). Wing strakes planform area may be added, if applicable; or

    The TC definition actually includes the fuselage area within the wing chord. If Van's uses the actual wing area, you could have about 12 square feet extra wing area by TC definition. That could be enough to allow you to increase the gross without requiring a type rating.

  • The TC definition, strange as it may sound, is actually the standard definition of wing area, used in aeronautical engineering since many decades. So, I would expect that Van used the same definition. The fact that Van's claimed wing area is 110 sq ft for the RV-4, 6 and 8, even though they have different fuselage widths (but the same wing span) suggests that his definition includes the fuselage area.

    I just installed one of my ailerons and measured the wing chord as 58.125 inches. With a wing span of 23 ft (as claimed by Vans), this would give a wing area of 111.4 sq. ft, if the wing tips were completely square. In fact, the leading of the wing tip is slightly rounded, so the actual wing area will be a bit less than 111.4 sq ft - Van's 110 sq ft number is probably fairly close.

    I checked the data that the CAFE Foundation recorded in their [url=http://www.cafefoundation.org/aprs/RV-8A%20APR.pdf]RV-8A Aircraft Performance Report[/url]. They list wing area of 111.2 sq ft, flap span of 58 inches, and flap chord of 11.25 inches. These numbers differ a bit from my measurements. If I use the CAFE APR numbers, I get a max allowable weight of 1888 lb, which is probably enough to meet my requirements. So, maybe I will point to those numbers as coming from an independent third party, and use them as the basis for my calculation.

    Kevin Horton

    Comment last edited on about 5 years ago by Kevin Horton