Lear Fan 2000

[speeddemon]

Re: Lear Fan 2000

Fighter pilots.....sheesh.

[King]

Re: Lear Fan 2000

We do X-Ray, Dye Pen, Eddy Current and many other things to find the hidden damage in metallic structures.

Or NDI stands for National Dance Institute.

[Air Race Addict]

Re: Lear Fan 2000

NDI means Non-Destructive Inspection. In the Air Force this is a group of specialists who look for metal fatigue using, among other things, an x-ray process used to detect metal failures -- cracks and such beneath the surface that aren't visible during a normal inspection process or by using dye penetrant.

My point was that, if the anonymous poster's assertion that "When a metal part fails, it fails on the outside where you can see it", then there would not be a need for such a shop.

Since the Air Force (and I imagine the rest of the aviation industry) spends lots of $$ on such men and equipment, my guess is that the anonymous poster is incorrect in his statement.

Hi Randy, You are correct. As a currently working A&P (well, I'm at home right now, HAH!), but we have composite stuff all over the CRJ 700 and Q400's that we have in our fleet. The Mtx department has their own NDT, (Non Destructive Testing), people that perform eddy current, X-ray, ultrasound, and the most basic test of all that we use in the field, the old tap test. It's amazing what you can find just by tapping lightly on parts like prop blades and any other part for that matter. So, the assertion that you can't find problems in composites is ludicrous. Just my .02 worth.
Bill

https://www.airraceaddict.com

[Unregistered]

Re: Lear Fan 2000

magnaflux and dye penetrant locate cracks on the surface that usualy undetectable by visual inspection. In the case of the c-130a fire bomber that went down, there were visable stress cracks on the spar. What I meant was metal usauly fails by showing signs on the surface of the part. Composites can damage without showing signs on the surface. My statements that not wanting to fly anything made strucualy from composites is my own opinion and preference, not that it's been provn to be unsafe. How many certified composite aircraft become succesful and are in wide use today? Although I'm sure the number will be growing in the future.

[Peashooter]

Re: Lear Fan 2000

Part of the condition isnpection for an EZ is tapping the surfaces with a nickle and listening for a nice sharp report. Anything that returns a thud is suspect for delamination. Knock on wood, I'm clean after 18.5 years of operation.

"Turn your head and cough!" That'll be $75!

[Air Race Addict]

Re: Lear Fan 2000

Part of the condition inspection for an EZ is tapping the surfaces with a nickle and listening for a nice sharp report.

Well, I didn't want to say it Peas, but size does matter I prefer to use a quarter

[speeddemon]

Re: Lear Fan 2000

Sheesh.......A&P's

[Unregistered]

Re: Lear Fan 2000

In the case of the c-130a fire bomber that went down, there were visable stress cracks on the spar. What I meant was metal usauly fails by showing signs on the surface of the part.

Actually, the cracks were not visable on the surface. One had cracks on the spar fittings, and the other aircraft had a repair (doubler) and the crack grew underneath the repair.

Just goes to show you, just because a nice doubler has been installed the area in question is not without added stresses.

Wood (natural composite) has the same characteristics as synthetic composites (carbon, fiberglass, nomex.etc.), you won't fly in a wood airplane either?

[matt]

Re: Lear Fan 2000

i know the feeling speed...

[Peashooter]

Re: Lear Fan 2000

Well, I didn't want to say it Peas, but size does matter I prefer to use a quarter

Susan B said I squeezed too hard, and Sackajaweea said I was being insensitive...

[First time Juke]

Re: Lear Fan 2000

Wood (natural composite) has the same characteristics as synthetic composites (carbon, fiberglass, nomex.etc.), you won't fly in a wood airplane either?

Well Mosquito twin fighterbomber, yak-9, several finnish fighters ( Pm-1, Myrsky ) were of wooden design..Spuce Goose also.

Carbon seem to brake differently than wood or metal..metal bends..carbon brakes cleanly into two pieces ( in shafts for golf clubs for instance ). Wood kinda starts to wear down rapidly.

Pik-20 and LS-1 were at their time super sailplanes both made of fiber. Several boat makers still use wood..some couldn't live without carbon and fibres. The techniques are easy but need alot of molds and such...I think the optimatisation is the key: if you make it too lite it will brake...like Daedalos pedalled soarer..original broke down..next flew 199 km with cycling motion.

[Peashooter]

Re: Lear Fan 2000

Here's an example of a carbon failure.

http://www.aafo.com/hangartalk/attachment.php?attachmentid=2105

The pre-molded carbon top and bottom skins are bonded to wood spars and sub-ribs. In this case, the top skin bond was inadequate at the center section (1/16" bond vs. desired 3/8") from the kit maker and the skin pulled away from the spar at an estimated 140 mph (carried 1 lb lead ballast @ cg), ripping the carbon skin. (@ bottom of a 1,000' dive ) The fuselage impaled in (mostly) desert sand absorbing the forces in a linear manner which minimized damage. The fuse is a glass/kevlar composite. The v-tail is carbon over wood as well. The ailerons and rudder-vators have "live" hinges, meaning the carbon skin is backed locally with kevlar allowing +/- 20 degree flexure. Oh, and here's the view UP the mountian from the point of recovery - about 500' @ +/- 50% pitch. Note the old car pushed over the side a long time ago.

The hollow-molded wing really sings at speed! Peas

[First time Juke]

Re: Lear Fan 2000

Nice slopesoarer Peas. I forgot that also Dh Vampire jet and Hawker Hurricane ( + HH 1 partially ) were made of wood.

I think the way they are doing passenger aeroplanes today using metal and composites together to optimize weight and strength is just fine.

I remember reading about english Mustang chasing Me 163 Komet into a deep dive and when pulling up the wings bent seveal degrees upward..the carbon wing would have most likely have snapped in the same situation..when the stress was at peak point..or the pilot broken his spine at a high G-load. He did loose conciousness for a while.

[Unregistered]

Lear Fan 2100

Actually, the model number was the 2100. I started with the company back in 1979 when it was called Lear Avia. I was their Purchasing Agent responsible for much of the raw materials and tooling. Would like to exchange stories with past emplyees, where they went after Lear Fan Ltd., etc.

Michael

[First time Juke]

Re: Lear Fan 2000

Michael did you ever catch any Lear Avia people to talk with ?