Wing grommets

[RoN43220]

AC43-13-1b says "Install drain grommets on the underside of all components, at the lowest point in each fabric panel, when the aircraft is in stored
attitude"

Researching wing grommet placement here I find that the recommended inspection procedure says "open drain grommets at each rib bay trailing edge".

My BC12-D was restored by a well respected professional and he put holes along the very trailing edge of wings and ailerons.

The IA I asked to do this year's annual says this compromises the integrity of the wing and wants to involve a DER. He interprets that grommets must be in the fabric before the trailing edge aluminum.

I like what I have but am willing to put additional seaplane grommets in. I'm curious of other's opinions on this and what you have on your plane. An additional question - because of dihedral would underwing grommets go in at the inboard point of each rib bay to be most effective? My plane has seen very little moisture so I discount any chance of corrosion in my trailing edge aluminum.

Thanks tribe.

[partyofone]

Re: Wing grommets

I may be wrong on this, but every time we installed the drain grommets, they were glued to the fabric, covered by the reinforcing tape and opened after the finish was done. they are forward of the trailing edge and on the outboard side of each rib.

Erik

[magman]

Re: Wing grommets

Another method is to use a hot nail or soldering pencil & just burn them in.

The heat fuses the fabric edge so no grommets are needed.

[guns68]

Re: Wing grommets

I did both. I glued grommets to the fabric and then used a soldering pencil to melt a hole. I guess that was overkill? Anyway, it works.

[Ray36048]

Re: Wing grommets

They go in the fabric. He should have not drilled holes in the trailing edges. You are going to have to do what ever your AI wants to get a sign off.

[Edwin Otha]

Re: Wing grommets

I would find a new Inspector. There are airplanes that have the holes in the trailing edge, Great Lakes I believe is one. They uses a 3 sided file to make their holes.
The holes are to let the wing dry out, not much more. Much ado about nothing.
EO

[lawheelock]

Re: Wing grommets

Unless you have monster holes in your trailing edge, they will not weaken the wing structure.
Larry Wheelock, IA

[magman]

Re: Wing grommets

Keep in mind if it doesn't WHISTLE in flight you do NOT have enough holes!

Trapped moisture can cause big problems.

[mulwyk]

Re: Wing grommets

So, that's what those holes are for! My project had trailing edge holes just like you describe. I didn't recognize them as drain holes, and so just covered over them. But really, having the holes in the trailing edge is a great idea. Otherwise any water that gets into the trailing edge is just trapped in there.

Like others I put my drains forward of the trailing edge and outboard of the rib. I used the soldering iron method. But, if I can still find them by feel, I'll open up a few of those T.E. holes.

[RoN43220]

Re: Wing grommets

Ah - as I suspected. Thanks for the confirmation. The guy that restored my plane is a stickler for originality. I didn't figure he drilled the holes in the trailing edge aluminum, just opened them up after recovering. I too think they have value there, find it interesting the Taylorcraft inspection procedure seems to describe them and they in no way compromise the integrity.

[Jim Herpst]

Re: Wing grommets

Oh good grief. Stuff like the IA is trying to pull sends me over the edge, Just my humble opine...... raised my blood pressure tooo. Tell him to read some more books.......

[Guest]

Re: Wing grommets

So, that's what those holes are for! My project had trailing edge holes just like you describe. I didn't recognize them as drain holes, and so just covered over them. But really, having the holes in the trailing edge is a great idea. Otherwise any water that gets into the trailing edge is just trapped in there.

Like others I put my drains forward of the trailing edge and outboard of the rib. I used the soldering iron method. But, if I can still find them by feel, I'll open up a few of those T.E. holes.

I would not worry about water being trapped in the trailing edge. The dihedral will cause it to run down to the root where it will drain if you make a hole in the fabric that cover the inboard end of the trailing edge.

I guess we should be sure to leave that open to drain when we recover.

Dave

[Buell Powell]

Re: Wing grommets

Another way to cut drain holes. This is a copy of a tool the military used that works well. It's just a piece of 1/4" tubing cut tapering to a point and sharpened. Glue the grommets (metal seems to work best as opposed to plastic) with Poly Tac and install reinforcing patches, -push the tool in and turn using the edges of the grommets as a guide-either before the finial paint coats works well to finish the hole edges or tough then up if cut after.I put a piece of 1/4" fuel line for a safety stop. I haven't tried a soldering iron but this makes a neat hole and only takes long enough to push the tool in to cut a hole. One thing that makes a difference in how well it works is to keep the cutting edges sharp.

[Forrest Barber]

Re: Wing grommets

Hi Buell, my Dad had one in his fabric covering tool box, I still have it too! He had a bigger wooden handle on it.

[Buell Powell]

Re: Wing grommets

Hi Forrest,
My Uncle that passed away a few years ago built and restored wood boats and made that and several tools when he helped me with some things for my Taylorcraft when I restored it from remembering tools he used working for the Air Force -He had a house and boat shop on the Guadalupe River -sure miss going out there-working in that shop-cooking fahitas @ chapupies, @ drinking a Shinner Bock in the evenings by that river.