Worried about a leading edge crack in the fiberglass wing laminate ofmy PW-5

[[email protected]]

Hi all.

I own a PW-5. I have a MM Fabrication Wing Rigger I use when put the glider together and take it apart.

Yesterday, a gust of wind caught the wing when it was vertical on the wing rigger, and even though I was holding the wing steady near the spar, the wind force was strong enough to topple the wing rigger and slam the leading edge on the ground (grass). Personally I think these wing riggers need longer wheel bases to provide more moment against moderately strong wind, but that is another story.

An initial inspection for damage showed a 3 inch crack in the fiberglass in the leading edge where it struck the ground. The crack is deep enough to show the square pattern of the underlying fiberglass cloth layer, so it's not just a surface crack. (A PW-5 doesn't have a gel coat anyway. It has a coat of paint over the fiberglass laminate.)

I'm now worried about structural integrity of the wing, of course. Should I be? What should be your next steps? or what would you do next if you were I?

Respectfully,
Charles "Ben" Ethridge

[chuck[_3_]]

< The crack is deep enough to show the square pattern of the underlying fiberglass cloth layer >

If you’re just seeing the outer layer of glass, that by itself might not be a structural issue.
Having said that, if you have a crack significant enough to see the glass underneath I think I’d get a knowledgeable person to inspect it. They might want to remove paint for a better look at the local area. What part of the country are you located?

[[email protected]]

Been there, done that..........First off, it's important to place the trailer into the wind and then don't rotate the wing to the vertical position until your lined up into the wind (behind the trailer). If your wing-rigger has lateral adjustment, recommend you restrict the movement by placing a piece of plastic pipe (split on one side) onto both sides of the axle. As for the damage, send me close up pictures of the damage and I'll try and advise..
JJ

[Steve Koerner]

I'm sorry to hear of such a mishap.

As JJ says there is never a need to expose your wing to the wind in a vertical position. You are vertical only when you are lined up with the trailer which is lined up with the wind. All maneuvering is always done with the wing flat. I've disassembled in windy conditions many times -- once in the middle of the night alone with a strong thunderstorm blowing in. If the wind is blowing you have to think it through.

JJ's comment about adding split plastic pipe might apply to an earliest version of sliding axle Wing Rigger before the development of the split cylinder locking clamp. The vast majority of sliding axle Wing Riggers were made (and still are made) with this amazingly effective clamp mechanism which asuredly does not need a plastic pipe helper.

Mark Mocho at MM Fabrication is on top of all this and his build quality is superb.

[[email protected]]

I see your point about lining up with the wind, but our trailers are all relatively permanently mounted blocked and chocked in one area and I would have to rent or borrow a tow vehicle each time, so putting the trailer into the wind is not a no-brainer at this particular field. I will make this suggestion to the field owner though, since others use a Wing Rigger and could suffer the same fate.

I have the later version of the Wing Rigger and I'm not questioning the quality. I'm pretty happy with it overall. I'm just questioning one aspect of the design. What would be wrong with, say, doubling the wheel base length? Wouldn't that at least mitigate the risk of a spill in situations where one can't turn the trailer into the wind?

The only downsides I can think of are that (1) it would add a bit to the construction cost a bit and (2) it would be a bit harder to pack in a trailer with a narrow front door.

[Justin Couch]

On Monday, 12 February 2018 04:20:59 UTC+11, wrote:
> Hi all.
>
> I own a PW-5. I have a MM Fabrication Wing Rigger I use when put the glider together and take it apart.
>
> Yesterday, a gust of wind caught the wing when it was vertical on the wing rigger, and even though I was holding the wing steady near the spar, the wind force was strong enough to topple the wing rigger and slam the leading edge on the ground (grass). Personally I think these wing riggers need longer wheel bases to provide more moment against moderately strong wind, but that is another story.
>
> An initial inspection for damage showed a 3 inch crack in the fiberglass in the leading edge where it struck the ground. The crack is deep enough to show the square pattern of the underlying fiberglass cloth layer, so it's not just a surface crack. (A PW-5 doesn't have a gel coat anyway. It has a coat of paint over the fiberglass laminate.)
>
> I'm now worried about structural integrity of the wing, of course. Should I be? What should be your next steps? or what would you do next if you were I?
>
> Respectfully,
> Charles "Ben" Ethridge

PW-5s are so lightly built that the crack is probably much larger than that under the bond. Get someone to check it out properly if it's anywhere inboard of the airbrakes.

[[email protected]]

Â*"What would be wrong with, say, doubling the wheel base length?"

if you visit the MM Fabrication website and find the page with WingRigger options, you will see that it IS offered with a wide-track chassis. The bottom tube that holds the hardened chrome axle is seven inches longer and incorporates three linear bearings instead of the two in the standard chassis. The axle is also correspondingly longer. Stability is improved, although few customers opt for this choice. The wide-track is standard on WingRiggers sold for large gliders, but is available for an additional $75.

[[email protected]]

> What would be wrong with, say, doubling the wheel base length? Wouldn't that at least mitigate the risk of a spill in situations where one can't turn the trailer into the wind?
>

Sorry to hear the story. Sounds like a knowledgeable person needs to check the structure.

A bigger rigger wheel base might get in the way when you try to get the wing near the glider to slide it into the trailer and remember, you are trying to keep something that likes to fly from flying in a gust. My guess is there is no practical way to make it big enough to fix the problem.

If the wind conditions are sporty, the tricks I've used are some combination of keeping the wind horizontal as long as possible, turning the trailer into the wind, finding a sheltered location, making a sheltered location with a big vehicle, getting some friends to help, and waiting for a lull in the wind.

I guess this is a part of gliding. To expect one person with any normal rigger to always work without precautions is optimistic. Just like in sailing, the wind is going to get respect one way or the other.

Good luck on the repair.

[JS[_5_]]

On Monday, February 12, 2018 at 6:07:50 AM UTC-8, wrote:
> > What would be wrong with, say, doubling the wheel base length? Wouldn't that at least mitigate the risk of a spill in situations where one can't turn the trailer into the wind?
> >
>
> Sorry to hear the story. Sounds like a knowledgeable person needs to check the structure.
>
> A bigger rigger wheel base might get in the way when you try to get the wing near the glider to slide it into the trailer and remember, you are trying to keep something that likes to fly from flying in a gust. My guess is there is no practical way to make it big enough to fix the problem.
>
> If the wind conditions are sporty, the tricks I've used are some combination of keeping the wind horizontal as long as possible, turning the trailer into the wind, finding a sheltered location, making a sheltered location with a big vehicle, getting some friends to help, and waiting for a lull in the wind.
>
> I guess this is a part of gliding. To expect one person with any normal rigger to always work without precautions is optimistic. Just like in sailing, the wind is going to get respect one way or the other.
>
> Good luck on the repair.

As others have suggested to the OP: Get the damage assessed by someone experienced in maintaining composite aircraft.

Not necessarily a factor here, but something noticed while riggers are used.. Some pilots like to have very little weight at the spar, so they aren't lifting much. This would be very easy to do with a wing as light as the PW5.
Having little weight in your hands can allow a casual grip on the spar. If there is a bump or a wind gust, this could lead to loss of control.
I'd suggest having sufficient weight at the spar to make you hold on.

I've only rigged a PeeWee the old fashioned way, but perhaps will get a chance to rig one in the next couple of weeks using the rigger kindly donated by Wolf-Dietrich Weber.
Jim

[[email protected]]

I've been solo rigging since 1982 almost every time I fly (originally my LS-3 but for the last 26 years, my ASW 24). I haven't built any WingMates in a while (maybe in the future) but one of the selling points was the ability to use it on any terrain, including plowed fields. It's actually more stable, easier on my body, and doesn't take much, if any, more time than if I'm using a crew.

But...I'm VERY careful in the wind. I use some of the same tricks mentioned plus one or two that are specific to my design (e.g., lowering the wing as far as possible until it's horizontal). But basically if the wind gets too strong and/or gusty, I ask someone to help. They don't have to lift anything! Big point. All they have to do is stand by the wingtip in case the wind tries to blow it over when the wing goes vertical. I've never damaged it in wind but I've had a couple of close calls.

If you have doubts about how much wind is too much, get someone to help. After 35 years of solo rigging, I'm actually more inclined to ask for that quick assist to "just stand there and push back on the wingtip if it starts to topple over" than I used to be.

Chip Bearden

[Steve Leonard[_2_]]

Two things caught my attention from the OP.

First, if using a rigger in a crosswind, do everything in your power to have the cradle set and LOCKED at the far upwind side of the axle before rotating the wing to the leading edge down position. Why? Give you the longest arm for overturning moment. Longer axle might help, but not if you are in the middle of it or at the downwind end of it!

Second, you have a glider and no way to haul the trailer around yourself? You said you would have to rent or borrow a vehicle to move the trailer. This seems a bit off to me. But, a car is not required to roll a trailer a wing panel length and turn it 90 degrees so it is pointed into the wind. Then move it back into the tiedown spot after you have rigged or de-rigged. Yes, more work, but minimal risk for damage that way.

Just my observations. Hope you get your wing repaired quickly!

Steve Leonard

[[email protected]]

On Sunday, February 11, 2018 at 9:20:59 AM UTC-8, wrote:
> Hi all.
>
> I own a PW-5. I have a MM Fabrication Wing Rigger I use when put the glider together and take it apart.
>
> Yesterday, a gust of wind caught the wing when it was vertical on the wing rigger, and even though I was holding the wing steady near the spar, the wind force was strong enough to topple the wing rigger and slam the leading edge on the ground (grass). Personally I think these wing riggers need longer wheel bases to provide more moment against moderately strong wind, but that is another story.
>
> An initial inspection for damage showed a 3 inch crack in the fiberglass in the leading edge where it struck the ground. The crack is deep enough to show the square pattern of the underlying fiberglass cloth layer, so it's not just a surface crack. (A PW-5 doesn't have a gel coat anyway. It has a coat of paint over the fiberglass laminate.)
>
> I'm now worried about structural integrity of the wing, of course. Should I be? What should be your next steps? or what would you do next if you were I?
>
> Respectfully,
> Charles "Ben" Ethridge

ANY damage to the wing forward of the mainspar MUST be inspected before further flight, repaired as necessary, and a logbook entry made.

[[email protected]]

> First, if using a rigger in a crosswind, do everything in your power to have the cradle set and LOCKED at the far upwind side of the axle before rotating the wing to the leading edge down position. Why? Give you the longest arm for overturning moment. Longer axle might help, but not if you are in the middle of it or at the downwind end of it!

I disagree, at least on a MM Wing Rigger. Imagine there is no wind at all. If you lock it on the open side of the wing rigger cradle, then entire weight of the wing now rests just above the wheel and becomes very unstable. (Got that t-shirt.) Now imagine the crosswind again. Yes, you are right, as long as you don't turn the wing so that it is now parallel to the wind, which is going to happen when you put it in the trailer (also parallel to the wind) per discussion above. I agree that it's all about longer moment, but there are different ways to skin that cat. One of them would simply be a longer axle. This WOULD help for sure, even if you lock the in the middle. By locking it in the middle, you mitigate the risk of crosswind toppling it PLUS the risk of toppling it by simply having the wing weight directly over a wheel when you turn it upwind.

I'm curious what Mark of MM recommends on this, i.e. setting the Wing Rigger directly over a wheel.

>
> Second, you have a glider and no way to haul the trailer around yourself? You said you would have to rent or borrow a vehicle to move the trailer. This seems a bit off to me. But, a car is not required to roll a trailer a wing panel length and turn it 90 degrees so it is pointed into the wind. Then move it back into the tiedown spot after you have rigged or de-rigged.. Yes, more work, but minimal risk for damage that way.
>
Yes, I do. The glider lives in its trailer at the airport. I only have a Honda Civic, so it may seem a bit "off", but it's true. I'm not just making an excuse here. I normally borrow my brother's truck to move it.

Further, all of the gliders are stored in one spot on the airport and they are all lined up quite close to each other so it is impossible to turn mine 90 degrees without first towing it away from the other trailers.

Thus far the best overall solution (in my particular situation) seems to be to get a (a) longer wheel base and (b) keep the cradle locked in the center (so that the wing weight is over the center of the wheel base) and (c) keep the wing horizontal as much as possible. (Here, I'm assuming there is no one around to hold the opposite end of the wing in case it decides to topple.)

I will also try to talk the airport manager into letting me move my glider to a different spot where I can turn the trailer 90 degrees as you say.

[[email protected]]

> ANY damage to the wing forward of the mainspar MUST be inspected before further flight, repaired as necessary, and a logbook entry made.

I'm trying to imagine how one would inspect this to make sure there is no internal structural damage. X-ray?

[Eric Munk]

At 11:51 13 February 2018, wrote:
>> ANY damage to the wing forward of the mainspar MUST be inspected before
>further flight, repaired as necessary, and a logbook entry made.
>
>I'm trying to imagine how one would inspect this to make sure there is no
>internal structural damage. X-ray?
>

That part of the wing does not have internal structure to speak of. Damage
to D-nose sandwich structure is easily detectable by an experienced LAME.

[[email protected]]

"I'm curious what Mark of MM recommends on this, i.e. setting the Wing Rigger directly over a wheel."

Charles- There is no problem with positioning the chassis and wing cradle all the way to one side or the other to counter a crosswind. The PW-5 has a lightweight wing, and when rotated to the vertical position, it becomes a pretty big sail. Moving the vertical column to the UPWIND side and locking the axle (!) can help by giving more lateral support. Remember that you are not actually "setting the WingRigger directly over a wheel." The axle support tube is ten inches long, so the vertical column is offset. (Not so much on the side the saddle is rotated to.) The most important step is securing the lateral movement with the axle lock knob (and checking it before moving!)

However, if you want a longer axle, contact me and we can discuss options.

[Steve Leonard[_2_]]

On Tuesday, February 13, 2018 at 6:48:32 AM UTC-6, wrote:
> "I'm curious what Mark of MM recommends on this, i.e. setting the Wing Rigger directly over a wheel."
>
> Charles- There is no problem with positioning the chassis and wing cradle all the way to one side or the other to counter a crosswind. The PW-5 has a lightweight wing, and when rotated to the vertical position, it becomes a pretty big sail. Moving the vertical column to the UPWIND side and locking the axle (!) can help by giving more lateral support. Remember that you are not actually "setting the WingRigger directly over a wheel." The axle support tube is ten inches long, so the vertical column is offset. (Not so much on the side the saddle is rotated to.) The most important step is securing the lateral movement with the axle lock knob (and checking it before moving!)
>
> However, if you want a longer axle, contact me and we can discuss options..

Yes, Mark and I go a long ways back on riggers. As he said, one key to the design is to make it so you CAN NOT get the CG of the wing over a wheel when the wing is either level or leading edge down. You can accomplish this by not putting the vertical member of the chassis on the center of the axle support tube. I haven't seen one of Mark's recently, but I know I did this on mine something like 15 years ago. And most importantly, LOCK the the rigger to the axle. If not, it will have impressive velocity when it hits the other end of the axle, and away she will go!

If your trailer does not have a "jockey wheel" on the front of it, I would encourage you to consider adding one. This makes it so you can push your trailer out of the row, turn it 90 degrees (if the wind says you should do so), put the plane away, then push the trailer back into the row.

Oh, and I think I have a longer axle on my rigger than most. It isn't an issue for storage as it is still shorter than a collapsed wing stand.

There have been many improvements and refinements over the years as these designs have evolved. And there will continue to be more as time goes on. Good that yours has the support of Mark Mocho. Mine is a one off and it is all on me to refine!

Steve Leonard

[George Haeh]

I'm happy to have a helper when I'm derigging in a breeze.

Station the helper on the downwind side of the rigger when you're rotating
the
wing to vertical so he can keep the rigger from blowing over.

Simply put if there's a good breeze, you must point the trailer into the
wind or
find at least three strong helpers.

[Charlie M. (UH & 002 owner/pilot)]

Honda Civic?!?!

I crewed (late '70's?) for a person from near Boston with an original "super Beetle" (oxymoron.......) with a ASW-15 and a large plywood trailer.
Empty trailer on flat ground, I was looking to draft motorhomes to maintain 55-60MPH on a highway........
Loaded trailer......sigh......Frikkin forget uphill........

Your Civic can do well pulling a trailer, just moving it around an airport, sheesh, no issue.

Yes, a helper is great, but not always available.

[Bob Whelan[_3_]]

On 2/13/2018 4:49 AM, wrote:
<Snip...>
> ...The glider lives in its trailer at the airport. I only have a
> Honda Civic, so it may seem a bit "off", but it's true. I'm not just making
> an excuse here. I normally borrow my brother's truck to move it.

It took a while, but eventually sufficient rust fell off my memory cell, thus
regenerating a coupla possibly-actionable anecdotes...

- some years ago a soon-to-be friend arrived at my home field (KBDU) towing an
original PIK-20A in an original PIK factory trailer behind a 2nd-generation
Civic. They'd moved from Louisiana with the rig. Not the cutesy 1st-gen
liquid-cooled-engine Civic, but its slightly supersized successor (that soon
allowed Honda to show its after-sale customer support by warranty-replacing
beaucoup rusted-through front fenders). It was years before he replaced that
particular tow-vehicle. Anemic in the mountains, but he never killed it
mechanically by using it in that manner. Memory sez he had some sort of
generic tow hitch installed on the vehicle.

- even more years ago (1973!) I bought a generic tow hitch (from Sears!) to
install on my 1972 Maverick. It didn't fit properly, but I was lucky enough to
have Wil Schuemann as an officemate, who welded-it-to-necessary-length, plus
welding on 2 triangulation braces. Trouble-free towed gliders with that
car/hitch until I sold it in 2009!

- ~2000-ish I installed a generic hitch on my eventual-wife's 1987 4-banger
Mustang which she used for several years to tow a 1-26, including to/from Air
Sailing (NV) and Dalhart (TX) from eastern CO. Health forced her to sell the
1-26 ~6 years ago; the 'Stang's original engine/tranny/running gear are
presently returning from the moon with ~275k miles on 'em.

Bob W.

---
This email has been checked for viruses by AVG.
http://www.avg.com

[[email protected]]

LOL. Where there's a will there's a way!

I'll try that with my Honda Civic coz I LOVE my glider. The Honda Civic -- ehhh...not so much. :-)

Seriously, thanks for all the advice, people.

[[email protected]]

Oh Eric. Pardon my ignorance, but what's a LAME?

[Darryl Ramm]

On Tuesday, February 13, 2018 at 3:04:36 PM UTC-8, wrote:
> Oh Eric. Pardon my ignorance, but what's a LAME?

LAME: Licensed Aeronautical Mechanical Engineer. UK/Commonwealth version of an A&P.

[OregonGliderPilot]

On Tuesday, February 13, 2018 at 3:04:36 PM UTC-8, wrote:
Oh Eric. Pardon my ignorance, but what's a LAME?

LAME: Licensed Aeronautical Mechanical Engineer. UK/Commonwealth version of an A&P.

To be pedantic, in the UK it is Licensed Aircraft Maintenance Engineer.

[Dave Nadler]

On Tuesday, February 13, 2018 at 6:04:36 PM UTC-5, wrote:
> what's a LAME?

Many postings on RAS?

[[email protected]]

On Wednesday, February 14, 2018 at 10:34:19 AM UTC-5, Dave Nadler wrote:
> On Tuesday, February 13, 2018 at 6:04:36 PM UTC-5, wrote:
> > what's a LAME?
>
> Many postings on RAS?

It's rude and lazy to generalize. Names, please. :)