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Originally Posted by Greyhead Further to the adjustable tail incidence (post No. 79 above). Having had a few sessions with the Acrowot to get my thumbs up to speed again after the winter recess, I got the Elf out for it’s pre-flight checks.
Of course the Laser fired up “first flick” and ran faultlessly but when I checked the nut on the tail incidence adjuster it stripped the thread with only slight torque on the spanner. It was actually the rod that had stripped; it was one of the 2mm rods from the model shop with a thread at one end. I needed a short rod; about 50mm long, with a thread at both ends so I’d tapped the extra thread. When I investigated the problem I found that the rod as supplied has a “rolled” 2mm thread but the rod itself is only 1.7mm diameter. All had seemed OK when it was made but obviously with vibration from the engine and the load when elevator is used, the undersized thread wasn’t good enough for the job.
At least I found the problem before anything disastrous happened and it re-enforces the need for regular checks and especially before the first outing of the season. |
*** Grahame,you were indeed very lucky to have spotted this failure,once I was doing a pre-flight on my old Leopard Moth and found a broken aileron horn hidden underneath the wing,it just goes to show that check,check & double check especially after a period of lay up where hangar rash can set in.Anything to do with flying controls is prone to fail,in full size practise anything like this gets two inspections,by two different people ! I know that this is not practicle in our case but there is certainly a lesson learned here.Never take anything for granted,it cost you a model at the least.