Ok, we have heard of Betts tests – what exactly is it?
The Betts test is a test to establish the strength of the wing fabric. The Dacron that the majority of microlights are covered with degrades with exposure to sun light, specifically ultraviolet exposure. The fabric can get weak enough to just poke your finger through in very bad cases, so to provide an early warning of impending failure, a chap called Clive Betts came up with a simple test.
The Betts tester is simply a Salter spring balance, fitted with a bent sewing needle (shaped like a hook) in the end, . The test is conducted by sticking the hook into the fabric at several locations along the wing (usually concentrating on the upper surface) and pulling a specified minimum load on the scale. If the needle starts to tear the fabric at the minimum load, then the fabric has failed the test and needs to be repaired or replaced. As wing covers are expensive, this is a very useful way of determining if the microlight you are looking at buying is good value, plus, for some older microlights new wing covers aren’t available, making the aircraft pretty much scrap if the wing fails the test.
All microlight inspectors have to have a Betts tester, they can either be bought from Conrad Beale’s store or they can be made very easily from a standard Salter spring balance and a sewing needle (for a lot less money than the one badged as a Betts tester!).
If you’re seriously looking to buy a microlight, then take an inspector along with you and ask the owner if the wing can be tested. If the owner says no, then I’d suggest not going further with the deal! See the video below for an example….