DG300 gear collapse! Common problem?

Yesterday my gear collapsed during rollout on my DG300 Elan. It had first done that last season on touchdown. At that time, I was advised to replace the strut which holds the gear-knee locked straight. I did replaced it and had hoped the problem was solved.

The detent for the gear-down position seems iffy, but the manual suggests the gear is supposed to hold even without the detent.

Can anyone say if this is a common problem for DG300's and know of a solution? It wreaks a bit of havoc on my fuselage and serenity. The good news is that the 300 tracks quite nicely on its fuselage.

I have known gear system to collapse when there was not enough overcentre on the knee joint. I replace an undercarriage leg on a glider which subsequently had a unfortunate retract on landing and I found that the detent locking system at the control handle was still in the locked down position. It did not have enough overcentre in the knee joint. The big lesson I learnt was that the detent alone won't prevent the problem. And yes most systems should stay fixed down without a detent or lock on the control handle. There are several manufacturers that do not have any detent or handle locking on the undercarriage down.

I concur with John. Remove the knee joint assembly and make sure the over center is generous and most importantly that it has no springiness in the joint. As this will , in a bounce, amplify and in fact over come the strut force that is holding the knee straight, as well as over center. The springiness is normally caused by ill fitting contact plates and hinge alignments. No load should be on the handle as the tubes and cranks are designed only for forces to retract or extent the landing gear. Regards

Hi Greg, I believe it is a fairly common problem. We have had it happen twice in ours. We have now replaced the gas strut, although the old one seemed to be pretty much up to pressure when tested after removal. There was a bit of dirt build-up on the surfaces of the ends of the struts which come together when the gear is extended, which may have prevented that strut coming fully into the over-centre position. This would certainly make it more likely to collapse when load was applied. Cheers, John G.

Yesterday my gear collapsed during rollout on my DG300 Elan. It had first done that last season on touchdown. At that time, I was advised to replace the strut which holds the gear-knee locked straight. I did replaced it and had hoped the problem was solved. The detent for the gear-down position seems iffy, but the manual suggests the gear is supposed to hold even without the detent. Can anyone say if this is a common problem for DG300's and know of a solution? It wreaks a bit of havoc on my fuselage and serenity. The good news is that the 300 tracks quite nicely on its fuselage. Thanks.

Last one I heard of was about 3 weeks ago on a shiny new 303, but I also know of a 100 that used to have a similar problem.