Wing rib stitching

[On Glide]

Can someone point me to a reference for information on wing rib stitching? I believe there are some rules on what wingloading and VNe limits there are on requiring rib stiching, stitch spacing etc.

Reason for asking - I'm looking at an LAA aircraft with a view to purchase and it's missing wing rib stitching where I would expect to find it.

Thanks, OG

[Rod1]

On Glide

Give LAA Engineering a call, you will get the right answer right away. Do you have an appropriately experiences LAA inspector to do a pre purchase inspection, preferably the same chap you will use after?

Are you a member of the LAA? If not, Join!

Rod1

[hatzflyer]

Certain fabrics are advertised as not needing rib stitching if the ribcaps are of a size that allows gluing only. However I wouldn't feel safe without it. There are several variables and this type of information is becoming a lost art due to all the "old boys" retiring.

Pm me if you want with the following info and I may be able to help, but would say the best bet is if you can find a more local inspector who has knowledge of fabrics to inspect the a/c for you.A list is available on the LAA website.

What type of plane,where do you think its missing i.e wing / tail ,how far from the root etc.
What type of covering ?

[Genghis the Engineer]

I don't have my copy to hand, but the ASA Aviation Mechanics handbook is pretty good on this.

Also you could try the FAA repair manual: AC43-13b, which is easily found online with a bit of searching.

G

[SNS3Guppy]

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/99c827db9baac81b86256b4500596c4e/$FILE/Chapter%2002.pdf

Table 2-1 will give you applications for given airspeeds, fabric weights, and types.

Table 2-2 will give you applications for lacing and stitching material.

Read the entire chapter for detailed information regarding stitching and types of fabric work, tests, and repairs.

[Justiciar]

Suggest you PM Stiknruda, as he has done it very recently on at least two aircraft.

[stiknruda]

All Stik will do is point you to FAA repair manual AC43-13b, unless it is a Pitts or an Eagle then he could tell you over the phone!

Stik

[On Glide]

Thanks for all the replies so far. AC 43-13 is informative but doesn't give much design advice, largely falling back on 'put the fabric back as per the type design' line.

The type in question is a Jodel 117. It is covered in Ceconite but the only rib with stitching is the one at the dihedral break, probably to stop the fabric lifting off. It's such a slow speed, low wing loading aircraft that it's probably fine (been flying for >15 years since last recovered) but I just want to be sure it's OK. I have a call in with LAA engineering so hopefully they will have an answer, but if anyone knows about the matter, drop a line on this thread.

OG

[SNS3Guppy]

Onglide, I'm not sure what it is that you're asking, here. Are you asking if rib stitching is necessary or required? Are you asking how to rib stitch?

If the Jodel uses stitching on only one rib, are you asking if another source will tell you to do more rib stitching? Not sure what it is that you're asking.

AC 43-13B (change 1) will give you ample information on how to rib stitch, and what materials to use, in considerable detail, including step by step directions on a proper seine knot.

The actual sequence of what to do on the rib stitch varies a little with each type of fabric application (stits, ceconite, etc), and you'll need to refer the specific manual for each application. Generally adhesive such as Superseam for the ceconite process will be painted on the surfaces to be stitched, a strip of ceconite layed over, and then brushed through with MEK to draw the superseam into the weave. Then the fabric over the top, shrunk down, then another reinforcement tape. Then the rib stitching, then another tape over the top of that, and in some cases, another rib stitching pinked cover over that...depending on the aircraft and the process.

Far more aircraft use mechanical means other than stitching these days, over ribs and supporting structures.

Whatever you do, don't mix processes, such as stits and ceconite.

Stitch spacing and methodology should match the original installation (or plans, if building from plans)...which is what AC 43.13b also directs. Changes from the original installation are considered a major repair or alteration.

I'm not entirely certain what it is that you're asking. If you want to know about the rib stitching spacing, then visit table 2-12 in AC 43.13b.

Again, the table won't tell you what to do in a specific application where the manufacturer or designer has specified a different spacing or type of stitching; the table and the circular are there to provide guidance when no other guidance is given.

I realize you're talking about the Jodel 117, but the LAA Acceptance Sheet for the Jodel 1050 specifically states regarding wing rib stitching:

www.lightaircraftassociation.co.uk/engineering/TADs/304%20JODEL%201050-M1.pdf
11. Standard Options
Fabric can be attached by bonding to the wing ribs with Super-seam cement (or equivalent) rather than rib stitching, but only if rib cap strips are fitted and fabric anchored at wing dihedral break in accordance with Jodel drawing G1 and translated covering notes available from LAA.


Note that this refers back to the Jodel drawings, as well, just as AC 43.13b will.

You noted that no rib stitching is in use on the ribs beyond the dihedral break...but are capstrips in place or ribs past that point?

[Nipper2]

As posted above, no rib-stitching needed if suitable cap-strips fitted. You need a 'Jodel Man' to do your pre-purchase inspection and look after your LAA maters once you have bought the aircraft. Where in the country are you? I may know someone who can help.

PM me if you need more info.

[Piper_Driver]

I stitched fabric on a sailplane once. My memory is rather foggy as this was nearly 40 year ago, but from what I remember the stich spacing - if required - is determined by the VNE speed of the aircraft. In addition, if an undercamber airfoil is in use stiching is required to maintain the proper airfoil geometry.

[hatzflyer]

It is acceptable to only stitch that rib on the lower powered 11 series jodels, DEPENDANT on the type of covering/glue used.
However I have always stitched them all.
How long has it been since it was re-covered?
Who recovered it?
What is it covered with?

It is possible to rib stitch retrospectively but it will Knacker the paint finish.
John,LAA inspector 493

Edited to say..
Sorry I just re read your last post and realise some of the info is there.
A friend of mine was in a similar situation recently .He bought the plane but wasn't happy so we stitched it .
I think it will probably be OK but if you get cought out in bad turbulance its just one more thing to worry about, and will you be happy to fly it to VNE when doing the airtest for the permit renewal?

[rogcal]

If you can lay your hands on a copy of the "PFA Handbook" you will find within all you need to know about stitching, doping, materials, etc.

What I learnt from it has served me well for over 25 years and I'd still refer to it if I was uncertain of a particular method.

[cockney steve]

It's such a slow speed, low wing loading aircraft that it's probably fine (been flying for >15 years since last recovered) but I just want to be sure it's OK.

Am I thick?....or am I missing something?

OVER 15 years have elapsed, that means it had initial inspection and approval by a properly qualified person and, (unless it's a hangar queen) it has had at least 14 subsequent ANNUAL inspections by qualified persons.

I would think that any likelihood of it being of "dubious" airworthiness,has long been disproved. :)
If you're that anal, I'd suggest that "rag n' sticks" flying is not for you, consider a factory-built spam-can. :}

just get it flown....it'll add a bit of frission to the otherwise routine

[stiknruda]

I once had a CAA Engineer pop up to do a survey on an aircraft that was due to receive a new CofA, having been grounded for 7 years.

He spent ages going through the logbooks all the way back to 1940, when it was built at Cowley, Oxford. We then went out to the hangar and he spent some time ensuring that serial numbers and placards were correct. After about 40 minutes, he declared himself satisfied and as we were leaving he turned to me and said, "You know I always remember Tiger Moths as being higher than yours!"

I tried really hard to contain my laughter. In order to get the a/c into the hangar, I'd removed the main wheels and the stub axles were sitting on two "skates". The Tiger was about 10" lower than with the wheels on.

Obviously a thorough inspection as he did not appreciate that the camouflaged and yellow Tiger had no main wheels.

People only inspect the things that they are looking at - it is not unreasonable to assume that the rib-stitching could have been incorrect for many years.

[SNS3Guppy]

Am I thick?....or am I missing something?

OVER 15 years have elapsed, that means it had initial inspection and approval by a properly qualified person and, (unless it's a hangar queen) it has had at least 14 subsequent ANNUAL inspections by qualified persons.

I would think that any likelihood of it being of "dubious" airworthiness,has long been disproved.


Steve, you're not thick, but you're definitely missing something.

Never, I mean NEVER, assume that simply because the aircraft is alleged to have been inspected, that it's safe. When you go fly, you're responsible for making that determination yourself.

I've had all manner of experiences involving problems following an inspection..even aircraft which have been "trouble free" for many years. I've performed inspections and found tens of thousands of dollars worth of problems...in aircraft which had been declared problem-free by previous inspectors and mechanics.

Some years ago I took a job as Director of Maintenance for an ambulance operation, flying King Air's. I soon discovered that the maintenance program was grossly in error, and found hundreds of hours discrepancies in parts, components, cycles, landings, etc. I found the wrong standard for measuring time on the aircraft was in use, missing log entries, missing airworthiness directives, and one requirement out of date by eighteen years. It was two phase inspections in error, given the other record keeping oversights, and numerous incorrect things had been done to the aircraft which required correction.

I've pulled an airplane out of maintenance only to return it not once, but seven times...each time during the preflight I'd find something else wrong. This, after the mechanic assured me he'd performed a check flight following the maintenance. I found the tanks bone dry, the ailerons rigged backward, all the inspection plates missing on the underside of the aircraft, etc.

I've found tools left aboard, wire bundles and other things blocking controls, cracked spars, broken wheels or gear, cracked control surface attach brackets, and so forth. Never assume that simply because someone else looked it over and signed it off that it's safe, or even airworthy.

Never overlook the mechanic out there, most likely the one you don't know about, who signs off inspections for a fee, but never looks at the airplane. Don't assume...assumption and guesswork in aviation will get you killed.