Hello, I am new to this club and type of aircraft. I am seriously considering purchasing a KCAB that has been restored and recovered but has wood spars. The refurbish company told me the spars were in excellent condition. Do I need to reconsider and only try to find planes with metal spars?
Decathlon purchase
- Thread starter bbailey
- Start date
Hey bbailey I'm kinda new to this site and offer my opinion as follows.
Never trust unless you can verify . The only time one can fully inspect wood spars is with the covering off. Not an option now, trust?? I decided to make Aca metal wings a must for my purchace. The problems with continual annual inspections and probably having more ia's think screw this I'm not taking the responsibility for these old wood wings, get new one would haunt me every annual Also you get new everything , tanks, bellcranks, 100 lb gross weight increase etc. Boy I'm gonna get it now. PS got royally screwed by an ia (can't see the plane on Sunday I'm busy at my church) on a purchase so I verify now. Good luck. Happy 7kcab driver
Never trust unless you can verify . The only time one can fully inspect wood spars is with the covering off. Not an option now, trust?? I decided to make Aca metal wings a must for my purchace. The problems with continual annual inspections and probably having more ia's think screw this I'm not taking the responsibility for these old wood wings, get new one would haunt me every annual Also you get new everything , tanks, bellcranks, 100 lb gross weight increase etc. Boy I'm gonna get it now. PS got royally screwed by an ia (can't see the plane on Sunday I'm busy at my church) on a purchase so I verify now. Good luck. Happy 7kcab driver
Ron86654
New member
Here are my thoughts on Wood vs. Aluminum. I have posted this before.
Wood vs. Aluminum
A recent thread on an aviation forum got me to wondering how we have arrived at this point where it is an “accepted fact” that Aluminum is superior to Wood as a material for building airplanes (specifically wings). So, here are some thoughts on the subject.
Up until the end of WW II most small airplanes were built using a lot of wood because Aluminum was hard to get and expensive because of the war. An airplane manufacturer had to hire a team of Craftsmen to build their wings for them. A labor intensive process, but hey, labor was relatively cheap and you could find artisans who knew how to work with it.
During the war a lot of airplanes were manufactured and they needed to be built as quickly and cheaply as possible, stamp out the parts and rivet them together. It wasn’t difficult to train unskilled labor to do this and a lot of machines could be used in the making of the parts.
The war ended and Aluminum became easily available and cheap. There were a lot of people available trained in the metal airplane process. Labor costs started to rise. In 1946 Bill Piper changed his J3 wing spars from wood to aluminum. Not because they were better, but they were cheaper. There were some aircraft manufacturers who resisted the change. Bellanca was one of them and gained a reputation of making an incredibly strong and tough airplane. Why? Because they retained the wood, they didn’t go to aluminum like the “spam cans” at Piper. Everyone knew at that time that wood was stronger, lighter, and more flexible than aluminum. But economic and marketing forces are impossible to over come. Soon advertiser were asking the new to aviation customer, “Why fly in the old fashioned wood airplane when you can have a new, modern aluminum one?”
Wood wings didn’t go from stronger, lighter, and more flexible to inferior overnight, it took a lot of years of marketing before that was an accepted belief. Think about this, with a wood spar a competent inspector can tell if it is airworthy. You can’t say that about aluminum. Aluminum has its own problems including fatigue and corrosion. A friend of mine just 3 weeks ago had to replace both wings on his 172 because of corrosion, advanced corrosion. When it was found it was way beyond unairworthy. These kinds of stories don’t stop people from buying aluminum wings. Why? Because everyone these days knows that aluminum is what you make wings out of. So if you have a problem now and then, so what?
Sorry for the rambling on, but it just bothers me that we are such slaves to marketing and technology that we lose sight of the fact that in a lot of cases the old ways were better. I think that wooden spars is an example of this.
Ron
Wood vs. Aluminum
A recent thread on an aviation forum got me to wondering how we have arrived at this point where it is an “accepted fact” that Aluminum is superior to Wood as a material for building airplanes (specifically wings). So, here are some thoughts on the subject.
Up until the end of WW II most small airplanes were built using a lot of wood because Aluminum was hard to get and expensive because of the war. An airplane manufacturer had to hire a team of Craftsmen to build their wings for them. A labor intensive process, but hey, labor was relatively cheap and you could find artisans who knew how to work with it.
During the war a lot of airplanes were manufactured and they needed to be built as quickly and cheaply as possible, stamp out the parts and rivet them together. It wasn’t difficult to train unskilled labor to do this and a lot of machines could be used in the making of the parts.
The war ended and Aluminum became easily available and cheap. There were a lot of people available trained in the metal airplane process. Labor costs started to rise. In 1946 Bill Piper changed his J3 wing spars from wood to aluminum. Not because they were better, but they were cheaper. There were some aircraft manufacturers who resisted the change. Bellanca was one of them and gained a reputation of making an incredibly strong and tough airplane. Why? Because they retained the wood, they didn’t go to aluminum like the “spam cans” at Piper. Everyone knew at that time that wood was stronger, lighter, and more flexible than aluminum. But economic and marketing forces are impossible to over come. Soon advertiser were asking the new to aviation customer, “Why fly in the old fashioned wood airplane when you can have a new, modern aluminum one?”
Wood wings didn’t go from stronger, lighter, and more flexible to inferior overnight, it took a lot of years of marketing before that was an accepted belief. Think about this, with a wood spar a competent inspector can tell if it is airworthy. You can’t say that about aluminum. Aluminum has its own problems including fatigue and corrosion. A friend of mine just 3 weeks ago had to replace both wings on his 172 because of corrosion, advanced corrosion. When it was found it was way beyond unairworthy. These kinds of stories don’t stop people from buying aluminum wings. Why? Because everyone these days knows that aluminum is what you make wings out of. So if you have a problem now and then, so what?
Sorry for the rambling on, but it just bothers me that we are such slaves to marketing and technology that we lose sight of the fact that in a lot of cases the old ways were better. I think that wooden spars is an example of this.
Ron
How come you get a 100lb gross weight increase with aca wings if wood wings are stronger. And your at the mercy of the "component inspector" if you can find one. Lots of ia's aren't willing to assume the responsibility for vintage wings. I don't blame them for not being a legal target. A Cessna with wing rot must have spent considerable time outside or in a corrosive enviorment, something a rag and tube most likely would not be exposed to. Just sayin. Wood vs aluminum not the issue. How to minimize being screwed was my thought.
wbecker
New member
First, I do agree with Ron on wood/aluminum spars. There is nothing WRONG with wood spars! They have worked fine for over 100 years.
However, I did buy new wings from ACA when I rebuilt my 8KCAB 12 years ago.
My reasons were:
1. The new wings are easy to inspect, by any A&P/IA. Not so with the wood spar AD.
2. The new wings eliminated the Pitot/Static tube sticking out where they get in the way, and get bent.
3. The new wings have the leading edge wrapped ALL the way around from top of the front spar to the bottom of the front spar, giving them
very good torsional rigidity.
4. The new wings have a FAR better wing to fuselage fairing design.
5. The new wings are 100% new, spars, ribs, tanks, everything!
6. The new wings are stiffer, giving better vertical penetration in aerobatic maneuvers.
7. The new wings have removable wing tips. Allowing strobe/nav light updates if needed, and makes it easy to make a rotisserie for when you
recover/paint the wings.
7. My old wings had good spars, but needed some work on ribs etc.
8. The wood wings have always had a problem with the rib to spar nails getting loose, if you use it for aerobatics, which was what I bought it
for.
I am not at all against wood spars, had them several other airplanes, no problems. But for my use, and the reasons above I chose new aluminum spar wings.
Bill Becker
However, I did buy new wings from ACA when I rebuilt my 8KCAB 12 years ago.
My reasons were:
1. The new wings are easy to inspect, by any A&P/IA. Not so with the wood spar AD.
2. The new wings eliminated the Pitot/Static tube sticking out where they get in the way, and get bent.
3. The new wings have the leading edge wrapped ALL the way around from top of the front spar to the bottom of the front spar, giving them
very good torsional rigidity.
4. The new wings have a FAR better wing to fuselage fairing design.
5. The new wings are 100% new, spars, ribs, tanks, everything!
6. The new wings are stiffer, giving better vertical penetration in aerobatic maneuvers.
7. The new wings have removable wing tips. Allowing strobe/nav light updates if needed, and makes it easy to make a rotisserie for when you
recover/paint the wings.
7. My old wings had good spars, but needed some work on ribs etc.
8. The wood wings have always had a problem with the rib to spar nails getting loose, if you use it for aerobatics, which was what I bought it
for.
I am not at all against wood spars, had them several other airplanes, no problems. But for my use, and the reasons above I chose new aluminum spar wings.
Bill Becker
wbecker
New member
By the way, I just completed a very extensive Annual Inspection on an 8KCAB with a set of Rainbow Ron's wood spars, they were EXCELLENT, I had no problem with them at all, even though the new owner bought it for aerobatic competition!
So I just wanted to make clear I have nothing against wood spars. I made my choice for the reasons given.
Bill Becker
So I just wanted to make clear I have nothing against wood spars. I made my choice for the reasons given.
Bill Becker
jonathankline
New member
Just do a very thorough pre-buy and find someone familiar with wood / fabric airplanes. The first 8KCAB we (me and my IA) looked at had varnish missing from a good section of the spar, and a couple of other minor issues. Being that we couldn't fully verify that spar (the airplane didn't have enough inspection holes cut to view the entire spar with a borescope), we passed on it, and I ended up finding another 8KCAB with wood spars a couple of months later that was in great shape. The airplane does great, it's hangared and I definitively do acro in it. If we ever end up having to replace a wing, then I might look at get new wings from ACA, but the wings on my 1980 8KCAB are in great shape, they have plenty of inspection holes, and they have been well cared for.
Cost vs. Benefit? You will pay 10-15k more for an airplane with the metal spars. Is it worth it for YOU?
First, find out if your mechanic is comfortable with the AD's and the wood spar. Don't have a mechanic yet? Find one first. Second, know that if you ever strip the fabric all the way off, there is a good chance you'll be replacing one or both. They aren't that expensive for replacements, but there is labor involved.
Now, get your mechanic to do the inspection of the spars in accordance with the AD before you buy the airplane. That will assure you that the guy that is inspecting them later, has already inspected them once and didn't find a problem.
Put the 15k you save in the bank.
ON the "is aluminum better" question. Jerry has answered this question pretty thoroughly before, but perhaps I can give some insight on this.
Apples to Apples, if you just slide out the wood spar and slide in an aluminum one (think the non-factory ALU conversions), the wing isn't any stronger or better, it just removes the AD inspection requirement and weighs more. AmerChampion took the opportunity when they put together their aluminum structure to redesign the whole wing. So the factory Alu wing AS A COMPLETE STRUCTURE is stronger than the wood one. That doesn't make it 'better' necessarily (although Jerry would disagree with me on this) but it is without question stronger. I have never and never plan to pull more than 3G's on my 5G wood citabria wing, so I do my inspections (i'm an IA) and don't worry about it.
If you are planning on doing Aerobatics on a regular basis, you probably fit into the profile of someone who would want the factory metal wings.
First, find out if your mechanic is comfortable with the AD's and the wood spar. Don't have a mechanic yet? Find one first. Second, know that if you ever strip the fabric all the way off, there is a good chance you'll be replacing one or both. They aren't that expensive for replacements, but there is labor involved.
Now, get your mechanic to do the inspection of the spars in accordance with the AD before you buy the airplane. That will assure you that the guy that is inspecting them later, has already inspected them once and didn't find a problem.
Put the 15k you save in the bank.
ON the "is aluminum better" question. Jerry has answered this question pretty thoroughly before, but perhaps I can give some insight on this.
Apples to Apples, if you just slide out the wood spar and slide in an aluminum one (think the non-factory ALU conversions), the wing isn't any stronger or better, it just removes the AD inspection requirement and weighs more. AmerChampion took the opportunity when they put together their aluminum structure to redesign the whole wing. So the factory Alu wing AS A COMPLETE STRUCTURE is stronger than the wood one. That doesn't make it 'better' necessarily (although Jerry would disagree with me on this) but it is without question stronger. I have never and never plan to pull more than 3G's on my 5G wood citabria wing, so I do my inspections (i'm an IA) and don't worry about it.
If you are planning on doing Aerobatics on a regular basis, you probably fit into the profile of someone who would want the factory metal wings.