When doing the first Form 2 on ZAX –S10-054 in 1995 the data sheet did not give any original wing frequency.
I contacted the factory and was advised it was not required under the regs. My LS3 manual demanded the frequency was checked with the fuselage supported on a rigid cradle due to its flexible undercarriage suspension. That was with a solid tailskid To get an acceptable and constant value on sailplanes without U/C suspension is nearly impossible unless tyre(s) pressure and condition are identical to the previous test. Noel. From: Aus-soaring [mailto:[email protected]] On Behalf Of Mike Borgelt Sent: Wednesday, 2 December 2015 12:20 PM To: Discussion of issues relating to Soaring in Australia. Subject: Re: [Aus-soaring] Wing frequency Procedure So the state of play may be summed up as: The wing bending frequency test may not detect even quite significant spar damage that is detectable by overt or less obvious means (tap test). It may cause a glider to fail the test where there is no obvious cause and the glider is grounded. Might be an idea to find another glider of the same type and measure its wing bending frequency and or find the last few years' history of the measurement. It can lead to further investigation which finds a problem Hmmmm.... This also means there could be cases where the wing bending frequency test is OK but other hidden damage could exist. If you want to do this test properly, the right way nowadays is to tape a small MEMS accelerometer to the wingtip and record the readings say 20 times a second or more. This device looks good and is wireless: http://axivity.com/files/resources/WAX3_Data_Sheet.pdf Probably good enough to tell if there is indeed a temperature sensitivity also. Good of you guys to think to do a wing bending frequency test on something obviously damaged, John, rather than just repair it right away. Mike At 09:34 AM 12/2/2015, you wrote: More than one case of the test not revealing a failure. An Astir CS which had been in a trailing crash. The underside of the wing about 1 metre from the root had an obvious impact over the spar region. The frequency test did not show any significant change. However when the damaged area was opened for repair it revealed significant damage to the spar cap and web. Regards, John Orton On 2 December 2015 at 08:48, Mark Newton <[email protected] > wrote: On 1 Dec 2015, at 9:42 PM, Justin Couch <[email protected]> wrote: > There is also one case where it didn't (Bathurst's DG300 that delaminated the > spar caps from the wing didn't pick up a freq change, but the tap test did). Interesting - I’ve spoken to Brits who had never heard of the tap test and were a bit bemused at Australia’s seeming obsession with it when they found out about it. Nice to know that it might be useful for something :-)  - mark _______________________________________________ Aus-soaring mailing list [email protected] http://lists.base64.com.au/listinfo/aus-soaring _______________________________________________ Aus-soaring mailing list [email protected] http://lists.base64.com.au/listinfo/aus-soaring Borgelt Instruments - design & manufacture of quality soaring instrumentation since 1978 www.borgeltinstruments.com <http://www.borgeltinstruments.com/> tel: 07 4635 5784 overseas: int+61-7-4635 5784 mob: 042835 5784 : int+61-42835 5784 P O Box 4607, Toowoomba East, QLD 4350, Australia
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