Will need help... my BD-12 was affected by Milton

[taylormarc]

I am going back to Tampa today to check on my planes... sadly my taylorcraft seems to have aileron damage. I have insurance but also an A&P mechanic. Lost my car on Davis Island and now this... seems all those black swan events are happening way too much. I travel a lot and in both cases couldn't come back in time nor had people willing to help me (ex-friends now) when I asked them to check on my vehicle and plane.

Anyhow... any opinion as to what the damage may be from this?

[Hank Jarrett]

If you are really lucky the cable between ailerons was already weak and snapped. Don't hold your breath. More likely the wind was banging the ailerons up and down and the hinge fitting failed (especially since you have a later post war plane with the cast ones). They are bad for getting corrosion under the steel end caps that can't be seen till the casting is badly corroded. If that happened you dodged a bullet. If the hinges fail in flight it is a bad day. Need to see more photos when you get the ailerons off. To get an aileron sag like that the center hinge would have failed but I would do a CAREFUL inspection of all three hinges on both sides with the steel caps OFF. You also want to check out all the pulleys for chipped edges and look for stretched cables. If you are going too pull cables be sure to pull a cord into the fuselage and wings with the removed cable so you can pull the cables back in again. TRUST ME! You DO NOT want to try and get any of the cables back in a covered plane with nothing to pull them in with!

Hank

[Robert Lees]

Taylormarc:
Don't knock your friends so much.
If I were your friend, I still wouldn't have rushed out during a hurricane just to check on the damage to your aircraft (or car) that I could do nothing about.

[Scott]

Most likely single point of failure is the magnezium as Hank says. The belcrank is visable through the false spar/aileron cove.

[taylormarc]

Hello everyone I was busy with the recovery. Well turns out the hinges as pictured above broke so technically very repairable... also will need a new rudder. Any ideas on these?
Is is possible to replace them without removing some of the fabric?
And yes maybe a blessing in disguise... definitely a BAD DAY if they break in flight. They both snapped for the ailerons so chances are if one would snap the other would do in flight.
Maybe I should carry a chute like Trevor just in case now when I fly it. JK

[braol]

I assume those solid mounting parts either have to be sourced from another airplane...I wonder how much to get those hinge fittings remanufactured??? (Has anyone put in inspection rings and removed/inspected these parts for that corrosion?)

[Hank Jarrett]

I hate those cast Magnesium hinges. They are a mass of cracks flying in close formation. There was a letter from the factory saying the welded steel and Mag hinges were interchangeable and OK to use pre war steel ones on post war wings and cast ones on pre war wings. It came out while Dorthy F. was running Taylorcraft. We have had several people show interest in making a fixture to make "Owner Produced" steel hinges but no one has carried through with making any. I designed a fixture to make them and figured what needed to be done by the "owner" to make them legal. I have been restoring my 45 fuselage so my hinges are still out of the wings to verify the fixture if someone wants to start a garage business making hinges.

[braol]

The ideal route would be to get them 3-D modeled with a laser scanner first and then cast from steel. We could post the data on this site for use by anybody and maybe make the casting blank avail for anybody who wants to get a sand cast made. I'm not sure on the costs for the scan but all good ideas have to start somewhere. Best to avoid someone's aileron leaving their airplane AND avoid FAA scrutiny at the same time. (Of course, a sand cast could be made with an existing part...I'm just throwing ideas out there.)

[Hank Jarrett]

FAR 21.9 (a)(5) establishes the legal basis for owner produced parts. The most important word in the FAR is "produced" as opposed to "manufacture". At a minimum the owner must be able to show that they were responsible for the parts production by defining the parts requirements, design and conformity.
The first requirement is design. The part must be a REPLACEMENT for the FAA approved factory (or authorized manufacturer replacement) part and it does NOT allow for modification. Replacing a cast magnesium part with a cast steel part, especially on a part of the control system, would NOT be allowed without a DER approval, which in the case of a steel hinge replacing an magnesium part would cost more for the DER than making a copy of a factory part. Making an exact copy of the cast magnesium part would be a slam dunk, except you would be replacing a failure prone old part with an equally failure prone new one. Where we get lucky is with the letter from Dorothy Ferris that said welded steel pre war and cast Magnesium post war hinges were interchangeable. A welded copy of the pre war hinge is much simpler to get accepted and I have yet to see a steel hinge fail unless the whole wing was rolled up in a ball. We don't have the factory drawing of the pre war hinge but we DO have examples to copy and the FAA folks I have talked to have said a good example of a part where drawings aren't available is acceptable for making a copy. The limitation is YOU CAN'T MODIFY the original design, especially in the control system!
Second step is CONFORMITY. We have to prove to the FAA that our part conforms to the original in all respects. The one we make must be JUST LIKE the original. On a hinge I think this would be pretty easy. We know the materials and finishes and I am sure we could satisfy the FAA.
As the "producer" of the part the person who will be mounting the hinge will need to participate in at least one part of either the design (the drawing), manufacture/material procurement, provide the actual manufacturer the fabrication procedures and assembly methods, provide the quality control procedures or personally supervise the manufacture. On parts I have made I did ALL of the above and it was a heck of a lot of fun and was very educational. The FAA only requires you do ONE.
I have made piles of parts for my 42 and 45 restorations and all have been signed off by several A&Ps and IAs (yea, I am kind of anal about it, EVERY part I have made was checked by more than one FAA rep). I have never had a part turned down yet.
If I needed hinges for one of my planes, I would have already done all of this. Who wants to step up to the plate? I am willing to help with guidance and whatever is needed to navigate the system. We CAN do this.

Hank

[Robert Lees]

(Has anyone put in inspection rings and removed/inspected these parts for that corrosion?)

Yes, see attached photo. I replaced mine with new ones sourced from the then Factory owner, Harry, bless his cotton socks.

[braol]

Is the corrosion from having a steel pin inside of a magnesium hinge? Or are those some kind of dissimilar metal insert on the end?

[Hank Jarrett]

It's Magnesium. It corrodes if unprotected if you look at it. And sometimes even if you don't look at it. It was the miracle metal of its' time, but the miracle came with a curse.

[braol]

It was the miracle metal of its' time, but the miracle came with a curse.

I am always entertained by stories of how the 'latest-and-greatest' thing often ends-up being a problem. I own a classic Porsche 911 and back in the early-80's Porsche decided to use titanium cylinder studs to hold their aluminum cylinders onto their engine cases. It turned-out that the coefficient of expansion of titanium vs. aluminum is VERY different and the bases of the cylinder of the Porsche 911 SC series of cars started cracking and had to be replaced by the manufacturer in a recall campaign. Such is progress I guess.

[Scott]

Magnesium alloys have come a long way, but the early versions are suseptible to pretty much all types of corrosion.

To me the greatest risk is that corrosion happily occurs under protective coatings without showing at the surface.

one key factor is preparation. Chromate primers actually promote corrosion of magnesium alloys so non-etching primers are the only option. But similar to aluminium alloys, primer/paint does not adhere well without some sort of conversion process applied to the surface.

The proper conversion coating for Magnesium contains hexavalent chromium and is no longer available. In 2014 when I was restoring CF-CLR I found a plating company in NY that sold wipes soaked in mag conversion chemical but they too are no longer available.

There are prepcoats available that claim to provide a paintable surface but it's not a true mag conversion coating.

Frankly, if you can't find or make steel brackets, I'd be inclined to clean an airworthy mag version using the prepcoat, but instead of paint maybe coat them with a non-curing corrosion grease like True Turn. Very sticky, transparent, yet still has capillary action capabilities, and is proven even in saltwater environments.

This would at the very least, enable on-going visual monitoring for corrosion.

[Scott]

Giving this a bit more thought, I believe there is a relatively easy solution (especially if you know someone with access to a CNC or even manual milling machine).

for the two standard hinges, duplicating the magnesium castings by machining from 2024T3 bar stock would be stronger, similar weight, and more corrosion resistant.

The aileron bellcrank/hinge assembly would be less straightforward but still a relatively easy candidate for CNC duplication.

I had considered making door handles from solid (using hand tools) but in the end found two acceptable ones.

All these magnesium parts are getting hard to find so machining from solid might be an option.
S