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  • Cowl fasteners

    Right ladies and Gents
    I realise this was discussed in 2010,
    in the very near future I will receive my Nynja kit ( no pressure PD) This will be ranger no 5 for me. This time I want to add cowl fastenings to a professional standard. Some one must have worked out the definitive make and model of fastener to use by now???
    Please help....
    Regards
    Damian

  • #2
    Cowl fasteners

    I have used The Southco 1/4 turn screws from Zygology for 10 years now and they have never let me down, easy to release and lift off the lid, easy to put back on, but a bugger to get the fixing right first time round. If I were to build another SkyRanger I would definitely go for the Southco solution.
    Adrian.

    Comment


    • #3
      Cowl fasteners

      There are a few problems to overcome to use quick release fastners.

      Most require some pressure to engage - and can flex the composite to cracking point doing so - so reinforcing the sides of the lower cowling is needed for these. A strip of Ali or similar.

      Most when undone protrude to some extent. On a cowling with curved sides ( Nynja is more curved still than SKR) this tends to result in the cowling still locked in place 'pegged' in position and resisting being pulled off. This in turn gives rise to ripping the fastners out of the cowling when trying to wrestle it off. Two ways to get around this - use fastners that come out when undone - (but then be careful not to lose them) or one solution used by the Israelli dealer is to make a hinged 'trap door' section on the lower cowling where it curves around the front - which falls backwards when fastner released.

      Ther are all a bit of a bugger to fit - they need accurate drilling and hole matching between parts, and may need different depths of fastner for different areas - deeper for instance where the firewall laps under thickening the material. It's important they clamp the cowling parts together solidly othwise all will jiggle in operation and wear. That can be a double headache if you use fastners that come out when released - you need to make sure you put them back in the right holes. Dzeus type fastners if not quite right can distort and grab. I spent half a day recently trying to get the bonnet of an Escapade that had used these - in the end we had to saw through several fastners which would not come out - whilst trying not to scratch the paint!

      I still prefer using screws. In the kits these days we use flanged panhead stainless screws, which with a hex screwdriver spin out really quickly. On our last demonstrator I experimented grommetting the holes in the top cowling to stop them wearing from contact with the threads during insertion and removal. I used Dzus grommets and their flanging tool which I modified by grinding down the lip so it fully flattened and clamped the grommets in position. So far 100 hours in the holes are good and system is working well, and looks neat and professional. Holes are around 6mm so nice and easy for alignment using the 5mm screws - no nasty out of alignment holes to grab the screws and cause cross threading etc. tool not super cheap, but I might be persuaded to lend ours out to builders.

      I also have started using rivnuts in place of the lug nuts - for now just on the rear edge where there is the firewall top to fix them Through as well as the glass fibre. These provide a solid fixing and resist the holes pulling. The rivnuts tool is not expensive and rivnuts can be used in lots of other places - like the centre console and instrument panel - where they are neat and work well. So a good tool to buy for a build.

      Paul

      Links to Dzus grommets and tool and rivnuts tool:
      http://www.lasaero.com/site/products...e?id=V01AHJ5JZ http://www.lasaero.com/site/products...e?id=V01XC83F9
      http://www.pvrdirect.co.uk/productin...FTDJtAodFiUAlQ

      Comment


      • #4
        Cowl fasteners

        Thanks Adrian & Paul,
        I have seen some poor attempts at faster fitting, hence why I asked the question.
        On my swift build I used lots of rivnuts where I could.
        When I had a C42 the camlocks just seemed to work , but I think the receivers are too large for the lip on the skyranger lower cowls?
        I'll have to find something else to occupy idle hands until the kit arrives!
        Best regards
        And have a happy Christmas

        Comment


        • #5
          Cowl fasteners

          Damian,

          I've used Camlocs on my Swift and my current Nynja: I'm quite happy with the results and consider them well up to the job. You say you've used them before, so I'm sure you don't need me to describe them. The important thing to get right, of course, is the length: those too long WILL fit, but stand proud when secured.

          Maybe I'm lazy, but I would find the prospect of unscrewing perhaps a dozen screws, possibly dropping one or two into the grass, just to do a daily inspection a disincentive; I'd still (reluctantly) still do it, since I'm an engine freak, but lesser men might not bother..... :-)

          I AM a big fan of rivnuts, about which I knew not, until Paul introduced them in the course of the Nynja build. I've used them to great success on the binnacle and other places, but far and away the best are those used to secure the front spat. The first attempt, at tapping threads in the front oleo legs was simply awful, with the spat wobbling about like a spare wotsit. Using rivnuts, it's really secure.

          Paul: I think the cause of your frustration was with 'Dzus' fasteners, although I concede you WERE probably cursing the Greek gods at the time!

          Comment


          • #6
            Cowl fasteners

            Camlocs are ok, but fall out after a few hundred hours as they only need the holes to elongate a touch to fall through. We tried them on one of our demo SKRs and they were disapointing after quite a short time.

            I have also flown a fair few school C42's doing instructor tests and they are quite fiddly and fall out. Also the pins in the. Wear and fall out or go asymmetric over time which can cause problems.

            I reckon it is quite a bit quicker using the screws well set up and with a hex head screwdriver so they can be spun out.

            After the post this morning I spent a bit of time looking at the fastners on the southco site. I quite like thesehttp://www.southco.com/en-us/09-12-17 they are threaded but with fast lead and captive so won't fall out. And I reckon the sadle receptacle used on the curved bits and with a slot cut upwards in the glass fibre, might just solve the 'Jacking out' needed to remove the panel which tends to lock it in position. Not sure how hideously expensive they are but I might get some samples to play with.

            Paul

            Comment


            • #7
              Cowl fasteners

              Thanks for the input guys...

              These look like they will pop out of the way to allow cowl removal, but would they cope with the curvature?
              Damian

              Comment


              • #8
                Cowl fasteners

                Dohhttp://www.ebay.co.uk/itm/DZUS-type-1-4-Turn-Self-Ejecting-Fastener-Complete-with-Spring-4-4-5-2mm-Panel/141331976169?_trksid=p2047675.c100005.m1851&_trkpa rms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3 D28111%26meid%3Df831a17801044720a1c98bee31c4fc06%2 6pid%3D100005%26prg%3D11472%26rk%3D2%26rkt%3D6%26m ehot%3Dag%26sd%3D111309986291&rt=nc
                try attaching the link !!!

                http://www.ebay.co.uk/itm/DZUS-type-...09986291&rt=nc

                Tried making the link live for you Damien but doesnt seem to work - maybe the gap which i closed has something missing?

                Comment


                • #9
                  Cowl fasteners

                  Damian Perkins wrote:
                  in the very near future I will receive my Nynja kit
                  We've got a kit on order too Damien, here's hoping for a Jan 2015 double-delivery?

                  Some interesting products on this site;

                  http://rhf.co.uk/quick-access-fasten...Ot4aAvUr8P8HAQ
                  (Trustee of the Bakers Dozen Syndicate)

                  Comment


                  • #10
                    Cowl fasteners

                    All these links are a bit bewildering
                    is there anything on this PDF worth trying out?

                    http://www.southco.com/static/Litera...9-12-17.en.pdf
                    (Trustee of the Bakers Dozen Syndicate)

                    Comment


                    • #11
                      Cowl fasteners

                      Hi Damian

                      I used the Camloc's over here. They have lasted well on the agent over here's aircraft. By the way I also put two each side of the binacle to alow quick opening should I need to have a look. I had the screws in and then decided on the change, very easy as you just drill for the camloc and its receptical. Just check what your allowed to do over your way.

                      I'm about two weeks off taking to airfield for the inspection and then the first flight etc. There is another Nynja just finished over here and it should fly within the next week.

                      I'd be keen to see an image of the exhaust bracket fitted to the pipe below no.4, at the exhaust pipe connection and also any info about if you fit static ports in the fuse in the UK.

                      Cheers

                      Mike

                      Attached files

                      Comment


                      • #12
                        Cowl fasteners

                        Hi Mike

                        We don't have any brackets on the downpipes - unless you mean the sliding joint on the starboard front? We also don't use any external static - we just use cockpit static with the static ports on the pressure instruments free vented. It results in no worse pitot static errors than the external vents we were using on the Skyranger.

                        With camlocs the problems we found were that with the big retaining washers holding the barrels right in the inner protuberance pegs the bonnet on making it very difficult to remove and refit - Phil Rigby has used these and when it was in for final inspection and test flying it caused me to swear loudly at the awkward things!

                        Using the small retaining washers option which allow the barrels to be withdrawn leaving only a shallow protuberance would probably fix that, but I used them on a Skyranger and it wasn't long before the holes in the cowling wore enough to let the small washers pass through and then they would fall out and get lost in the grass. If you can get away with them all being the same depth size the maybe best to fit them without retaining washers and remove them when undoing. Or another idea might be to bond a thin Ali or stainless plate with precision hole on the inside of the cowling rim at each fastener point to resist wear.

                        Paul

                        Comment


                        • #13
                          Cowl fasteners

                          Hi Paul
                          Thanks for your time and information. Yes I did mean the exhaust support on the stb side; as I have made one like in the build manual. (Were these designed due to promoting loosness during start and stopping of the 912's?) I have a CKT exhaust on a ULS2.

                          Does your shop sell springs that fit the CKT S/S exhausts?

                          Do you sell the colour stickers that go on the fuse and wheel spats. I'm after a set for the fuse and cowl and the three wheel spats, don't require the fin ones if possible. I've included a copy of the design i'm chasing.

                          Regards

                          Mike

                          Attached files

                          Comment


                          • #14
                            Cowl fasteners

                            Ok - I think you mean an exhaust steady bracket that clamps on the down pipe and connects to the engine? We used one of those on the CKT exhaust we used on the Skyranger, but the CKT system for the Nynja who's shape size and position I specified and helped to prototype uses a smaller lighter can ( identified by having twin outlet pipes)and with less mass and a different position doesn't need one. You won't find one in our Nynja build manual - so maybe you are looking at the earlier Skyranger manual or something from somewhere else that has a picture of the earlier Skyranger system? Do you have the CKT nynja system?

                            That Nynja belongs to Chris Theakstone who has his own company that makes graphics, and he has done quite a few for other customers here. His email is chris@ctaviation.co.uk

                            Yes we can sell the CKT exhaust springs see http://140142.33.ekmpowershop.net/ck...ings-851-p.asp

                            Regards
                            Paul

                            Comment


                            • #15
                              Cowl fasteners

                              Hi Paul

                              Once again thanks for your time and prompt answers.

                              I do have the CKT exhaust with the two outlet pipes. The items were purchased about August 2012.

                              I'll remove the steady bracket I made. (I'm not sure of the building version that the original owner of my kit printed & I can't attach the word screen copy I made to show you.)

                              I have emailed Chris about getting a set of blue stickers.

                              I'll email the store if you like as I'll get 4 spare spings, a spare turn buckle and some other bits just to stock my spares on hand. Maybe even a spare wheel tube.

                              Best regards and many thanks
                              Mike

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