Posted by jb92563 on Monday, November 9, 2009 @ 11:53 AM:
I was wondering what the best way would be to tighten up some loose wood screws.
I have loose wood screws on the canopy hinge, another inside on the canopy latch, plus the wing fairing screws don't all snug firmly either.
I was thinking that I should take the screws out and coat the inside of the hole with CyanoAcrylate glue and blow some wood dust into the hole so that the wood dust and glue will harden and provide a better grip for the screw.
Any other suggestions?
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Posted by Jorgen on Monday, November 9, 2009 @ 12:44 PM:
Hi Ray,
that is indeed the question. The screws for the canopyhinges and the wing fairings get a lot of punishment and will get loose sooner or later. Our Fournieteer extraordinaire Bob Grimstead has made a very good post on that:
http://sbeaver.com/cgi-bin/fournier/cutecast.pl?session=vYbGWAAvJHofKnPVuIwOS7EoVE&forum=11&thread=491
But as they say there are more than one way to skin a cat, so I think it´s a worthy case for discussion. I have to confess that I´ve reverted to bigger screws sofar...
May the 4´s be with you/ Jörgen
Posted by JamesB on Tuesday, November 10, 2009 @ 11:21 AM:
I restored wooden boats for 15-20 years and use the technique that is commonly used for them.
For low torque applications that you want to sand easily: Mix a batch of epoxy (I prefer West system) and add microspheres to make a consistency of about whipped cream. The firmer the mixture, the more you may benefit from coating the hole with a thin layer of epoxy first. Make sure you mix well. Many people keep adding microspheres to the raw epoxy until it no longer runs off the mixing spatula. Once it has setup (e.g., over night), sand as needed, redrill and continue. This works well for gashes, etc. Has modest strengh; relativey easy to sand.
For higher torque applications where you want screws to hold with strength: Mix flox (chopped fibers) with epoxy to make a similar consistency. Same directions as above, but will make a stronger fix. Be sure to smooth your fix on the plane while it is still wet as it will be harder to sand when it's set up. Make sure your pilot holes are big enough. It's also easy to refill. Stronger, but harder to sand. Not such a good choice for gashes, etc., as the flox won't smooth as well as the microspheres.
Posted by Markku on Tuesday, November 10, 2009 @ 11:37 AM:
| Quote: |  | | Originally posted by jb92563
I have loose wood screws on the canopy hinge, another inside on the canopy latch, plus the wing fairing screws don't all snug firmly either.
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The canopy hinges are are not fasten with wood screws, there are M5 nuts inside the fuselage. If the thread is not damaged, you can use a drop of mild thread locking compound
Posted by eugenio on Tuesday, November 10, 2009 @ 01:44 PM:
Not exactly. originally there is a helicoil in the wood. In any case it is possible to glue in a threaded bushing if the hole is too large, or restore the hole as per James's instruction then re-thread it and install a new helicoil. In this case also a similar size with UNF or UNC thread can be used (easier for you US guys)
Eugenio
Posted by Jorgen on Tuesday, November 10, 2009 @ 05:12 PM:
Good Going Guys,
super posts - I always thought it was wooden screws, and have been reluctant to tinker with them. You know what they say: If it ain´t (definetly) broken, don´t fix it, but now I know how to fix the hinges.
I fear we opened Pandoras box: which thread is best and which is used in Fourniers? Is it perchance BSP (British Standard Pipe)? That discussion can reach the same magnitude as when the early Christian scholars had heated discussions about whether Christ possessed his robe, whether it was OK to buy absolution etc.
May the 4´s be with you/ Jörgen
[Edit by Jorgen on Tuesday, November 10, 2009 @ 05:13 PM]
Posted by Markku on Wednesday, November 11, 2009 @ 02:24 AM:
Eugenio is right, I was just trying to explain the principle. All bolts in fuselage have standard metric thread.
Posted by eugenio on Wednesday, November 11, 2009 @ 03:35 PM:
Thanks Markku, obviously original threads are metric, but thinking to US guys, it's easier for them to use an US thread, for example AN3 thread is very similar to M5, and switching from one to the other means only to fill the hole and re-thread it with a UNF helicoil or glue in an insert with that thread.
In any case all French and German built motorgliders and gliders use metric threads (and also airplanes like Morane and Robin)
Eugenio
Posted by Jorgen on Wednesday, November 11, 2009 @ 04:36 PM:
Thanks for good advice James, Markku and Eugenio. Just a comment on Ray´s original post- loose canopy hinges AND loose screw on the canopy latch: there is a connection!
I had the same problem- same loose screws. After take off from a somewhat bumpy strip the canopy blew open. Fortunately I managed to grab the canopy before it blew fully open, and could close it without loosing it or further damage. A bumpy strip can undo the latch if the latchscrew isn´t tight enough, and if the canopy blows open (which can happen during ground handling too) the canopy hinge screws take a lot of punishment.
May the 4´s be with you/ Jörgen
Posted by Bob Grimstead on Friday, November 13, 2009 @ 08:20 AM:
Hi Guys,
Loose canopy? :- beware, is the locking pin missing or worn?
As I see it, even if the latch is loose, it should not go over-centre and allow the canopy to open provided that pin is in place.
Somewhere a couple of years back I read an interesting piece entitled (in a computer English translation ) 'Stefano the Pitch-Bird' (which presumably meant Stefano the black-bird!) in which he had his canopy fly open at height (over the Alps?) because that locking pin was missing.
Take a look and take care.
Yours, Bob
Posted by eugenio on Friday, November 13, 2009 @ 04:16 PM:
Well, Stefano was an Italian pilot who was thinking to manage a motorglider like a car. He went in Germany twice to try to get it home in Italy after the purchase, but at the first attempt he lost the canopy because there wasn't the safety cotter pin in the canopy hinge, so when he unadvertedly touched the latch the canopy opened imediately and blow away so the RF3 went back to the starting airfield (Kirn). After one month or so he attempted to get it home again, but this time he went there without any kind of chart, relying only on a new handheld GPS so it happened that the GPS had battery problems so he got lost not knowing where he was and landed in an international airport without any call to the tower or FIC or anyone else, so he was grounded and prohibited to fly again in Germany. I bought the RF3 from him (he was so upset that he wanted to destroy it) and went to keep it with our CFI Italy Flight Leader, Paolo Capellini. a direct flight of 4.15 hrs direct from Envie to Kirn then back to Italy via France.
The canopy was lost in the Black Forrest in Germany, about 20/30 min. from Kirn.
The safety pin in the RF3 is a cotter pin in the hinge pivot.
In the RF4 and RF5 is a lever that butt against the hinge.
Eugenio
Posted by Bob Grimstead on Thursday, November 19, 2009 @ 10:35 AM:
Thanks Eugenio,
Now I understand the story a little better. The original translation was not too good.
And now that I know the latches and hinges are different between the RF3 and RF4, I understand even better.
But, whatever the reason, losing the canopy is a big thing. you get a face full of rushing air, which can be very disconcerting. yo also get increased drag, but worse, you lose a lot of lift, because your lovely long, high aspect-ratio wing effectively becomes two short, low aspect-ratio ones. Ask anybody who's lost the skylight out of a Cub. Same effect.
I have developed a habit. When closing the canopy, ALWAYS LATCH IT. Never leave it closed but not latched, thinking you will remember to do that later. One day you will not.
Yours, Bob
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