Discussion in 'New Member Introductions' started by Kadir, Mar 23, 2019.
Could anybody give any advice in inspecting wood structure of a 45 year old wood and fabric wing
The first thing, as with ANY repair / restoration / restification is to start by documenting the condition and details of the subject. Photos, photos, photos... and more photos. At every step!
Locate as much information,technical, sales and promotional, etc as you can. Search for and any available join type clubs.
And finally, start disassembling, tagging and bagging all part and hardware.
Does the RF4(?) have it's original covering, or has it been recovered in the past (45 yrs)? What condition is the covering in? Has it been hangared or stored outside. Use a punch tester to evaluate it. How many (if any) inspection ports are on the lower surface of the wing? They are easily installed. Video inspection cameras are quite common now and inexpensive. At this point, you should be able to make an educated decision whether to retain the existing fabric, or to strip the wing completely.
If repairs are needed, then you will almost certainly need to strip the fabric. If funds aren't an issue, then I would default to replacing the fabric. Will certainly make inspection and repairs easier.
Inspect general condition of all wood for cracks and breaks, glue joints, corrosion, cracking and security of all fittings and hardware, delamination of any plywood, etc...
Personally, I think the Fournier is an incredible aircraft. Are you familiar with Mark Calder? He designed the Wren ultralight in the late '70's, and has for the past few years developing an FAR 103 RF4 replica called the Robin.
Hope this is helpful. Looking forward to seeing your progress.
Mike(y) in OR
That is one of my favorite airplanes. Generally if you can see the wood under the varnish, you can see if it’s rotted or not. The technical correct way is with an ice pick. Poke places of interest. Soggy is not good. You are supposed to have varnish ready to paint over your marks. Most people look only. There is a WW2 PT 19 trainer at my airport. Wings are 70 years old never restored and look like hell. Goes flying just about every day the weather is good. History of the airplane is a good indication of good or bad shape. Hangared and flown is much better than project sitting outside under a cover.
Thank you very much for your long and informative explanation, it is so very nice of you to take the time to do this for me.
The glider in question is a 1974 build Fournier FR5B Sperber which is the long wing version with a 17m (56 feet) wingspan
Most of its life it was hangared in dry conditions but, last winter it was outside. The covering is original with patches and repairs to fabric.
I am intending to replace the fabric with Oracover as it is light and will not take an expert to recover.
I am however, concerned about the wood structure underneath as I peel the original fabric off.
I and also my friends here have a lot of experience with metal aircraft yet we have no knowledge of wood, glue, rot and other problems we may have with a wooden structure.
My question here is on how we inspect wood against structural weakening or glue failure.
We have pre inspected with horoscope and we don't see any blackening of the wood or obvious wet areas but, as it was parked outside under the rain and snow all winter we are worried of structural damage to the wings.
You might want to talk to Techtonics Tuning in Sheridan, OR. One of their people is very involved with the Fournier community.
21801 SW Rock Creek Rd. Sheridan, OR 97378
FAX 503 843-3933
Without an ex ray machine, about the only thing not visual would be a tap test. Although they make special little hammers a large coin will work fine. Solid sounds different than a bad joint. You can’t do that everywhere. Looking at everything is really the only real way. Bad glue lines look different than good even just barely sometimes. Someone twisting or flexing a panel may help make a joint slip while someone is looking. Pretty much you sit there with a bright light and look until you are convinced it’s good. If you are not happy doing that yourself, you will have to find someone with more experience.
Aircraft Inspection and repair (AC 43.13-1b) has a chapter on wood repair.
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