Any MX have tips on wood airplanes

[pfarber]

Seems like there are some good deals possible due to people being afraid of wooden wings/spars.

I don't see a huge issue, AC grade wood is out there for repairs.

Any MX deal with wood?

Is it a complete no go or just don't want the hassle?

 

[Magman]

My guess is there are 3 types of Techs:

1. Won’t deal with wood.
2. Will inspect but not repair.
2. Will inspect and perform repairs.

Splicing spars and plywood patches definitely requires a high degree of skill
along with time and patients. It seems overseeing a cabinetmaker may be an option for MX.

Mooney had published some Service Letters that were excellent when
dealing with their wooden models. Unfortunately; this knowledge also
leads to many aircraft retirements. Or is that good?

 

[Let'sgoflying!]

There are plenty of people flying wood airframes and enjoying them, not having wood difficulties.
Once you choose a type, find the online type club forum and read.
The Viking I owned for 20 years is still going strong.
95% of the maintenance was not the wood, it was the typical light aircraft things; firewall forward, landing gear, avionics.

 

[Doc Holliday]

 

[Bell206]

Any MX deal with wood?

No. Plenty still flying as noted. Unfortunately, the hesitation to own usually is based on recurrent ADs in some cases or the high costs to have them repaired. Even some mechanics I know have elected not to repair them anymore simply because of labor time and costs vs a metal aircraft. But if one is good with wood and fabric, they can be a great deal for the right person.

 

[Dan Thomas]

We had a student that bought a Bellanca 14-13 (predecessor of the Viking), figuring he would save money on training costs. At his first annual, AD 76-20-07 was carried out properly, and decay was found in the wing roots. The airplane was scrapped. https://drs.faa.gov/browse/ADFRAWD/doctypeDetails?modalOpened=true

Before I owned it, my Jodel sat outside in a swampy area for several years. When I restored it I had to replace or repair several areas of decay. Lots of work. But the engine was fine, no corrosion inside. Another Jodel owner on Vancouver Island tried some mild aerobatics and had the spar fail, killing him. Decay was found in it, the result of a wet environment. A friend bought a homebuilt Minicab from near Vancouver and flew it home. Then he found water in it, along with decay.

If you have a wooden airplane, you'd better monitor it closely. Keeping it sheltered is the best way to extend its life. Wood is strong but it's also fungus food.

 

[Magman]

Agree with Dan’s comments. Proper maintenance includinding drain holes
and bare wood touch up is essential. I recall a pic of a Mooney M-20A
failed Vertical Fin. A mushroom was growing there.

A bud had a nice M-18 that he was going to repaint. Fabric test before paint was well below minimums. Inspection of the glue joints resulted in becoming a MAJOR project. There are AD’s on both models as well as Service Info. When buying wood get someone with some familiarity with
the material. They don’t have to be an expert; just thorough and diligent.

 

[pfarber]

We had a student that bought a Bellanca 14-13 (predecessor of the Viking), figuring he would save money on training costs. At his first annual, AD 76-20-07 was carried out properly, and decay was found in the wing roots. The airplane was scrapped. https://drs.faa.gov/browse/ADFRAWD/doctypeDetails?modalOpened=true

Before I owned it, my Jodel sat outside in a swampy area for several years. When I restored it I had to replace or repair several areas of decay. Lots of work. But the engine was fine, no corrosion inside. Another Jodel owner on Vancouver Island tried some mild aerobatics and had the spar fail, killing him. Decay was found in it, the result of a wet environment. A friend bought a homebuilt Minicab from near Vancouver and flew it home. Then he found water in it, along with decay.

If you have a wooden airplane, you'd better monitor it closely. Keeping it sheltered is the best way to extend its life. Wood is strong but it's also fungus food.

There is a video of this AD being performed and he did find some decay and a broken rib.

I wish he would have went into more depth on the decay around the landing light. He said for that repair it was better to buy new wings? I wonder if that's due to labor or material? Labor I have lots of, money not so much.

Other than the moisture probe its almost exactly like a composite tap test inspection.

 

[pfarber]

My guess is there are 3 types of Techs:

1. Won’t deal with wood.
2. Will inspect but not repair.
2. Will inspect and perform repairs.

Splicing spars and plywood patches definitely requires a high degree of skill
along with time and patients. It seems overseeing a cabinetmaker may be an option for MX.

Mooney had published some Service Letters that were excellent when
dealing with their wooden models. Unfortunately; this knowledge also
leads to many aircraft retirements. Or is that good?

If I run a business I think having a specialty is critical. Wood and fabric shops are always in demand... but that experience is hard to get.

 

[Bell206]

I wonder if that's due to labor or material?

Labor in most cases as wood is more limited in how it is repaired than metal. It can be as high as 2x to 3x more in a major repair. Basic wood materials are still readily available except for some mahogany or birch verniers which if found can be a bit pricey.

 

[Dan Thomas]

There is a video of this AD being performed and he did find some decay and a broken rib.

I wish he would have went into more depth on the decay around the landing light. He said for that repair it was better to buy new wings? I wonder if that's due to labor or material? Labor I have lots of, money not so much.

Other than the moisture probe its almost exactly like a composite tap test inspection.

He mentions dry silicone spray as a release agent, and a latex-based sealer, for the leading edge fairing and rear spar attach cover. The Bellanca service manual differs significantly there: it specifies an automotive dumdum strip-caulk type of sealant, similar to the old Plasticene we, as kids, played with. It is basically a fine clay with an oil of some sort in it, and it releases easily when the covers are removed. It doesn't dry out in the space of one year, nor does it set like any glue.


American Champion, which owns the Bellanca Type Certificates, still uses it. It works to keep the water out.

On one airplane I did, those fairings had been glued on with construction adhesive, like PL2000, and it took me over eight hours to get the LE covers off. It left damaged fabric and paint that then needed repair. I think the airplane had gone through several annuals like that, meaning that the covers were not removed so that the AD inspection could not have been done adequately.

 

[pfarber]

that looks like the window seal i used around wood windows. It never dries out but it also has zero strength. We use a silicon release agent at work whenever we have to replace windshield I beams. They are sealed with PRC but silicon release agent is used.

I would be worried that the thickness would not allow the fairings to seal properly. Silicon release is very thin and conforming to surfaces.

 

[Dan Thomas]

that looks like the window seal i used around wood windows. It never dries out but it also has zero strength. We use a silicon release agent at work whenever we have to replace windshield I beams. They are sealed with PRC but silicon release agent is used.

I would be worried that the thickness would not allow the fairings to seal properly. Silicon release is very thin and conforming to surfaces.

The dumdum is soft and conforms to both surfaces easily. Zero strength does not matter; the screws are doing the holding. Silicone release agent will let that fairing lift the sealant off the surface if it's in the hot sun and expands and buckles a tiny bit, and now we have a path for water.

The Bellanca engineers specified that stuff. They did not specify any release agent because it is completely unnecessary. I trust the engineers much more than I trust random aviation "experts" that have little real-world experience. Such experts are the guys that use adhesives instead of specified sealants. They're probably the same guys that use RTV as a fuel fitting sealant instead of specified and approved sealants.

 

[pfarber]

The dumdum is soft and conforms to both surfaces easily. Zero strength does not matter; the screws are doing the holding. Silicone release agent will let that fairing lift the sealant off the surface if it's in the hot sun and expands and buckles a tiny bit, and now we have a path for water.

The Bellanca engineers specified that stuff. They did not specify any release agent because it is completely unnecessary. I trust the engineers much more than I trust random aviation "experts" that have little real-world experience. Such experts are the guys that use adhesives instead of specified sealants. They're probably the same guys that use RTV as a fuel fitting sealant instead of specified and approved sealants.

We all have seen manuals with just plain wrong drawings or instructions. To say that the original documents are pristine and perfect examples is a very large stretch.

Is there an original manufacturer document that says add CamGuard to the oil? No? But a heck of a lot of people do.

Just out of curiosity do you have a photo of the fairing installed with the dum dum tape?

What are your thoughts on this:

Looks like the sealant held and did its job