Aluminum gear

[Big Ed]

Then including the metal spar wings was just to sell wings?

No, metal spar wings were to address the issue with compression cracks, reduce potential for hidden damage due to ground loops, stiffen the wing for better roll rate, eliminate rib nail issues, and achieve a more efficient manufacturing process. At least according to their website.

From the publicly available information that I can find, I believe the gross weight increase is driven by the improved gear, not by any properties of the improved wing. It is only available with the improved wing because drop tests were only performed with the metal winged aircraft. That is total conjecture on my part, but this is the internet so pulling stuff out your 4th point of contact (Army parachuting term) is allowed.

 

[Big Ed]

Question: do the aluminum gear have to be painted, or could they be left bare or clear coated, like car wheels? That would look slick, especially combined with a polished spinner.

 

[Bartman]

I agree, polished Al. gear legs would look cool. the more we talk about it the more I agree ithe change to those gear legs isn't a horrible idea

 

[Big Ed]

the change to those gear legs isn't a horrible idea

It's a great idea, except for the $$. But then that's always the thing with aviation, amiright?

 

[Explorer]

I've been told the gear legs do bend but can be pressed back to the original spec successfully. The chap referred to above in WA does that type of work and yellow tags them I believe. Wouldn't hurt to give him a ring.

Copied over from a thread on BackCountry.

"Jim Hayton is the person you want to talk to about fixing gear legs.
(360) 661-3302 His prices are very reasonable."

 

[Bartman]

It's a great idea, except for the $$. But then that's always the thing with aviation, amiright?

urright

 

[Big Ed]

I've been told the gear legs do bend but can be pressed back to the original spec successfully. The chap referred to above in WA does that type of work and yellow tags them I believe. Wouldn't hurt to give him a ring.

Copied over from a thread on BackCountry.

"Jim Hayton is the person you want to talk to about fixing gear legs.
(360) 661-3302 His prices are very reasonable."

I reached out to Rainbow Ron. Am hoping he keeps some in stock.

 

[Explorer]

If you can raise Ron. Can you ask him if he personally does the repairs or is it farmed out to Jim Hayton who he networks with?

 

[Bob Turner]

Ron is a good guy, willing to help, and competent. Ask him about re-heat-treating the steel legs.

 

[Bob Turner]

The markup isn't totally unreasonable. Grove experimental gear runs $2500-$3000, gun-drilled. You need six bolts at $100 each average, plus expensive washers and nuts. You need the bars, which probably come with the kit. Throw in extra hardware and hydraulic fittings and the surcharge involved in certifying the gear in the first place, and inspection/QC/ drawings/handling, and six grand starts to sound maybe the high end of reasonable.

I have seen new Decathlons with polished legs. Mine are anodized, and I wipe them down after each flight - well, most of the time. If you do polished aluminum, polish monthly and after it rains.

 

[Big Ed]

I would prefer anodized. Did you

I have seen new Decathlons with polished legs. Mine are anodized, and I wipe them down after each flight - well, most of the time. If you do polished aluminum, polish monthly and after it rains.

I would prefer anodized. Did they come that way or did you have them done?

Price as of 2018 was $6,000 for the legs, and an additional $1,500 for the rest of the kit.

 

[aftCG]

Factory metal wings and aluminum gear TOGETHER increases max gross by 150. Either component alone does nothing, legally. Prior to the aluminum gear in 2004, there was a period where the max gross increase could be obtained with metal wing, extended spring steel gear, and upgraded bolts.

ACA webpage lists nominal empty weight for current 8KCAB as 1304 lb. My 1978 model has nominal empty weight of 1330 lb. The max gross increase plus weight decrease would result in a useful load increase of 175lb, enough to legally take off with 2 grown men and full fuel.

From what I have read, the max gross is determined at least partially by a drop test. The aircraft is loaded and dropped from a height of 4 feet to see how much weight would cause a prop strike. Since ACA only supports metal wing aircraft, they have never done the drop test for wood spar aircraft. If they did, they would likely get the same improvement. The fact that aerobatic max gross is unchanged suggests that the wing is not the limiting factor.

I believe, but do not know, that the aluminum gear are longer, stronger, stiffer, and lighter. The aluminum (or extended steel) gear also permits a 2" longer prop, such as the Extreme Decathlon uses.

Interesting. Previously I have seen that the ACA aluminum wings come with a 100 lb gross weight increase (and at least a good chunk of that increased empty weight).

As to drop test, yadda yadda. Here's the thing. The airplane is originally certified to a maximum gross weight, and it isn't structural. It comes from FAR 23.2120 dealing with climb gradient (not structure as most pilots assume).

We're on the same type certificate as the original Champ.

Our CAR 4 certified planes probably never had a drop test, but they must have been deemed good enough at the time. But anyone seeking to increase the gross weight will be expected to show there are no adverse effects. And certainly the potential added burden to the landing gear will come into question, and that might involve drop tests.

ACA would certainly not have spent additional time/money/effort to extend any increased gross weight to wood spar wings, which of course they would all like to go away. Would be good for us but I don't hold it against them.

As for the $100 bolts, when I ordered the replacements to my old U-bolt type I ordered the NAS bolts too (I recall them being a bit under $30 each, but the nuts and washers weren't cheap either). Well the parts that showed up came with the bolts even though the product description said they were not included. I was able to return the surplus bolts for credit.

 

[Tangogawd]

I've looked hard at aluminum gear for the gcbc, but then again, I already have 2 sets of scout steal gear that I could put on it...... goodbye useful load

 

[DanO]

Speaking of aluminum gear...where might I find/get a jack pad adapter for my SD? I recall having seen one that fit on the gear lear leg and allowed one wheel to be lifted off the ground for maintenance. Thanks.

 

[Explorer]

Wants and Needs.

I'd like to have the Aluminum Gear for the reasons stated above. However, it comes at significant cost. Would I be correct in thinking if you have concerns about the steel gear. Send them out to the shop to be reshaped to spec and then NDT for structural integrity. Cost $800 - $1000?

Ron would be able to offer some practical advice. Do steel gear legs ever snap due to fatigue or just bend? Don't know.

 

[Explorer]

"As for the $100 bolts, when I ordered the replacements to my old U-bolt type I ordered the NAS bolts too (I recall them being a bit under $30 each, but the nuts and washers weren't cheap either). Well the parts that showed up came with the bolts even though the product description said they were not included. I was able to return the surplus bolts for credit." aftCG

Somewhere on the Forum you had a picture of the pkg from Aircraft Spruce and part number. Can you post again please?

In the package came the flat bar, 2 bolts, 2 washers and 2 nuts?

Then you order the single inside attachment bolt, washer and nut separately?

Am I on the right track? About to order 2 sets. It looks like both Univair and Aircraft Spruce Stock them.

Thank you!

 

[Big Ed]

As to drop test, yadda yadda. Here's the thing. The airplane is originally certified to a maximum gross weight, and it isn't structural. It comes from FAR 23.2120 dealing with climb gradient (not structure as most pilots assume).

I do not think that is correct. From the sources I have found, max gross weight is determined by both structural and performance standards for airworthiness.

All 3 versions of the Bellanca Decathlon (FP, CS, and Super) have the same max gross weight, despite having very different climb performance.

 

[Big Ed]

Do steel gear legs ever snap due to fatigue or just bend? Don't know.

Bending is common enough that Rainbow Ron carries reconditioned sets in stock.

There are plenty of anecdotes on the internet of Citabria and Decathlon gear legs breaking, including one on this website. All the stories I ran across involved steel legs breaking at the stress point where they bend before entering the fuselage. I also found 3 accident reports in the 90's of Decathlon gear failure due to the old style U bolts breaking.

The Aluminum legs have only been around since 2004. Could be they have not had time to develop fatigue issues yet. Or could be they were engineered better than the old steel legs. Or both.

There are also plenty of anecdotes of prop strikes while wheel landing, due to poor pilot technique causing excess gear flex. All steel as far as I know. I personally witnessed 2 of those, and have heard enough tales of woe to know this is not unusual. Longer, stiffer legs would definitely reduce the chances of this.

Writing this makes me think that $7K might not be a bad insurance policy, especially if you give dual.

 

[Big Ed]

Speaking of aluminum gear...where might I find/get a jack pad adapter for my SD? I recall having seen one that fit on the gear lear leg and allowed one wheel to be lifted off the ground for maintenance. Thanks.

Aircraft spruce has the old style adapter that fits on the gear leg. I have one and it works, but is kinda wonky and will gouge up the paint. ACA strongly recommends not using that adapter with aluminum gear, as the angle of the two edges is different. They sell an adapter that fits on the lower strut attach point.

 

[Bob Turner]

On the braking:

Each new student of mine hears over and over again - " a sudden application of both brakes at very low speed will put you on your nose!"

We have one every year on our airport. Pilots cannot believe how sudden it is, and how it happens when you are barely moving.

Anecdotes are not data - I too would like to know how many gear legs have failed by cracking, and not during a ground loop or crash landing. I think one of our participants had one, but there was no discussion of what preceeded the break.