777Dave

777Dave

Well Known Member
Looking for some ideas....
I imported an RV-4 to Canada last spring and by rule, had to register it at the manufacturers recommended max gross.... 1500#s. To improve versatility and allow for some upgrades, I would like to raise it to 1650. Transport Canada requires that I substantiate my request. I have NO doubt what so ever that my a/c will handle the increase... any ideas that might help me make my case? As a bonus, my a/c has an 0-360 and performance is great. Weight and balance is not a problem for me either... I have run "extreme case" examples and still stay inside the envelope. My empty weight is 985#s.

Thanks in advance.
Dave
 
I don't claim to know anything about Canada Transport or how they determine things, but one of the factors I use when someone wants to increase their gross weight is by looking at the "G" loading specs. If for example your aerobatic gross is 1275 lbs. (I don't know what it is on a -4) and you extrapolate that to 4.4 "G"s (utility category) you could conceivably come up with a gross MTO weight of 1738 lbs. Of course this doesn't take landing gear loads into consideration. But it does consider most of the rest of the airframe.
 
loading

Thanks Mel, I believe the 4 max aerobatic weight is 1376 although I haven't had mine upsidedown (yet). What is the G loading formula(graph) that you used?

Deven, My prop is wood (Warneke) and panel is simple, steam...no Horizon but I do have a gps/comm and transponder as well as a fuel comp. The a/c was weighed recently and is accurate.

Dave
 
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777Dave said:
Thanks Mel, I believe the 4 max aerobatic weight is 1376 although I haven't had mine upsidedown (yet). What is the G loading formula(graph) that you used?

Dave
Click to expand...
Are you sure? Aerobatic gross for the -6 is 1375. I would have thought it would be less for the -4.
 
aerobatic

Could not find a reference on Van's website but Dan C.'s website indicates 1375.

Dave
 
777Dave said:
Looking for some ideas....
I imported an RV-4 to Canada last spring and by rule, had to register it at the manufacturers recommended max gross.... 1500#s. To improve versatility and allow for some upgrades, I would like to raise it to 1650. Transport Canada requires that I substantiate my request. I have NO doubt what so ever that my a/c will handle the increase... any ideas that might help me make my case? As a bonus, my a/c has an 0-360 and performance is great. Weight and balance is not a problem for me either... I have run "extreme case" examples and still stay inside the envelope. My empty weight is 985#s.
Click to expand...
Dave,

Has TC provided any clues as to what exactly they are looking for? I am only aware of the following weight-related regulatory requirements for amateur-built aircraft in Canada:
  • max weight of 5,000 lb (was 1,800 kg, but changed to 5,000 lb via Exemption 549.01).
  • max wing loading requirements to avoid a need for an individual type rating (which were substantially relaxed by Exemption 549.01).
  • a minimum engine power requirement which varies with weight.
  • a climb performance requirement (note that you can't show compliance to this requirement until after receiving approval to fly at the higher weight).

Note that there are absolutely zero structural design requirements, so TC has no business asking for a structural justification. But a pissing contest won't get you too far, as they hold all the cards. They don't have to actually come up with a valid reason to deny your request - they can just sit on it for a few years while they cogitate. If they decide to send it up to Legal for an opinion, that will take at least six months to get an answer.

Regulatory requirement or not, the laws of physics apply equally to amateur-built and type-certificated aircraft, so you would be wise to apply appropriate limitations to your operation when above Van's recommended gross weight. For example, I plan to eventually request a higher gross weight for my RV-8. I will restrict the load factor when above 1800 lb such that the product of load factor times weight is less than the max recommended aerobatic weight times 6g. I will also only operate from smooth, hard surface runways when above 1800 lb, and I will apply lower cross wind limits.

If I were you, I would provide clear justification for all the weight requirements in AWM 549 (as amended by Exemption 549.01). Then, I would note that while there are no structural design requirements for amateur-built aircraft, you recognize that the laws of physics still apply, and for the information of TC, explain how you will limit your operation to ensure that the structure is adequate.

Disclaimer - I work for TC, but not in the part that deals with amateur-built aircraft.
 
I'm going to try to keep it light too!

Kevin, I think the TC requirements listed will be no problem for me.
I did not know that structural limits were not an issue! Interesting. I think your approach is good and I have spoken to the chap at Pearson that deals with these issues and he seems very reasonable. I will have to sit down a do the necessary calculations.

Great to see your airplane is flying! Having fun?

Dave
 
Dave, In the UK the RV4 has always been approved to 1550lbs by the LAA. Yes I know you want 1650, but I just thought I would mention it since it is a small part of the way to where you want to go.

One thing I would say is if you get your 1650 you will have to be very careful to guard the landing gear since this is undoubtedly the weakest feature on the aircraft with many damaged firewalls. Perhaps restrict yourself to metal runways for landing near that gross?

Good luck!
 
utility?

Just a thought, Cessna and others have a "Utility" category, lower gross weight to be able to do spins and maneuvers that require higher "G" loads. Thinking that Kevin is barking up that tree. I'm planning to do the same down here in Southern Canada(USA), to add fuel in the rear seat area.

RV-4, not just another pretty face, but the prettiest.

Randy, working on my 2nd 4, wings and tail
 
Need a letter from Vans

I had the same question for TC when I imported my -4. The gross weight as registered in the US was 1548. I was told that the only way I could exceed the design gross weight (1500#) was to get a letter from Vans. I was also told that while these letters used to be available, Vans will no longer provide them.

I was more interested in speeding the process of registration and decided not to pursue it, but I will be interested in the outcome of any attempts to register at a gross weight above the published design weight.
 
Update

Well I did a bit more homework and incorperated many of the suggestions mentioned in this thread and submitted a package to Transport Canada here in Toronto.... waited about 5 weeks, including Christmas and New Years and received authorization to conduct climb tests up to MTOW 1650#'s. I will do this in 3 steps and do not anticpate any performance issues. All it will take is some decent weather! Raging blizzard here today, :rolleyes:

I have worked out 3 W&B configurations that keep me inside the envelope (takeoff and landing) and work me up to 1650. A friend at RAA (Brampton) has provided some steel plate for ballast... I weigh 180#s and will have to wear a divers weight belt and carry several bucking bars to get myself up to 230#s for the last flight.

Dave
 
new weight

Well it took a while (away for about a month) but TC finally approved my request and I have a new Special C of A with a MTOW of 1650# for my RV4.
TC were very helpful and cooperative and :) This summer I will be able to fly legally with a reasonable weight passenger and full fuel and a bit of baggage. Feels good.
Might even think about a few mods?

Cheers
 
Good news

Dave, what paperwork did TC require from you to approve this?
 
TC

In a nutshell, they needed:
1) Letter requesting increase in MTOW. I included some info about g loading, weight and balance(important) and several other precautions that I was prepared to take at high weights.
2) Statement that there have been no changes to a/c config since original flight permit issued.
3)Confirmation w & B up to date, no changes.
4) Copy of log entry documenting climb test result. (I did 3 tests at increasing weights, 50# increments)
5) $35 fee.
6)New climb test report (form 24-0091)
7) Original Special c of A and operating conditions.

Cheers
 
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