Nose wheel collapsed with towing

[PeeJee]

Last Friday (for the second time) my nose wheel collapsed during towing. The two actuator struts of the nose wheel broke from the wishbone lock.

This was during towing and it collapsed during the braking action.

The main gear was out of the lock also, but did not collapse. There is no damage in the actuator area. We have a lot of questions.

1. How can the wishbone break?

2. How is it possible that when the nose gear collapse, that the main gear is out of lock?

This all started when my FBO forced my gear through the limits (2 years ago) with damage to several gear actuating parts.

 

[Fly Boomer]

9 minutes ago, PeeJee said:

This all started when my FBO forced my gear through the limits (2 years ago) with damage to several gear actuating parts.

How was it repaired two years ago?  Based on the lack of paint around the breaks, it looks like this has been happening in slow motion for quite some time.

[PeteMc]

Don't know if you can still find one, but there were little tubes with locks that prevent them from attaching a tow to the nose wheel.

Sounds like you could use one!

[EricJ]

Using the nosewheel structure to stop the aircraft with very much deceleration is extremely risky.   I'm not too surprised that this can happen.

[N201MKTurbo]

I have a feeling the nose wheel links were set way too tight.
 

When towing the plane, or taxiing over rough terrain, the nose gear will go from over-center to having tension on the over-center link making it straight instead of over-center. I could show you if we were under a jacked up plane. You can do it by pushing the nose wheel forward. It will move about 1/2 inch or so. The actuator links need to have enough spring travel so they are not fully compressed when the over-center link is straight with the wheel pushed forward. If the spring fully compresses the stress on retract links must be high enough to buckle the rods. This is orders of magnitude higher than the rods were designed for. It looks like the truss broke instead of the rods.

[PT20J]

Rich's @N201MKTurbo analysis makes sense. It's surprising that the truss gave out before the retraction tubes (which I believe Mooney calls bungee assemblies). FOUR truss tubes are broken pretty cleanly and near, but not at, the welds. I wonder if the truss was somehow compromised before the incident?

 

[Fly Boomer]

42 minutes ago, PT20J said:

Rich's @N201MKTurbo analysis makes sense. It's surprising that the truss gave out before the retraction tubes (which I believe Mooney calls bungee assemblies). FOUR truss tubes are broken pretty cleanly and near, but not at, the welds. I wonder if the truss was somehow compromised before the incident?

 

First post says "repaired" two years ago, but doesn't say how or by whom.