Nose Wheel Strut Failures

[Waddles]

We are trying to determine if there have ever been any nose wheel strut failures in gyros. If you know of one or more, please post here or send me a PM.

This is not a witch hunt, merely an attempt to determine if we need to specify a minimum fore/aft load on the nose wheel assembly.

I can't recall any problems, but my memory is no longer what it used to be.

Thanks.

Regards,

Waddles.

[RossM]

Hi Allan,
who was it on the forum who had a engine out. did a forced landing in the field. When trying to taxi out of the field, the nose strut gave way.
Nick ????? alarmist.

[Waddles]

Vague recollections of that now Ross. That was Nicknak I think was his forum name. Haven't seen or heard of him for a while. I had a failure in my original Butterfly gyro too but that was a faulty weld so doesn't count.

Waddles

[RickE]

G'day Allan,

I just remembered that one of our pilots at Somersby had a front wheel strut failure a little while ago. It is a home built machine and was doing some taxiing practice with two on board on our relatively rough runway.
The owner is OS at the moment. I will get him to contact you when he gets back.

[RossM]

Allan
in NiqueNaque post, also mentions of a another collapse
quote
as happened with my machine and also John"s machine at Denman when he had his accident a few years back,

[BrownBMB]

Allen, I remember way back in "91" sitting beside " Jacko" in his side be side air command during take off & we had one collapse. We hadn't quite broken ground, gave me a fright but was all handled by Dave exceptionally sweetly as be expected... man he could fly that bloke!

[Waddles]

Thanks All. Keep it coming.

Waddles.

[Paul C]

G'day Allan, Rick mentioned my homebuilt machine. The failure was a bent shaft at the point where the shaft met the wheel structure. The cause seemed to be two up running up and down quite a rough runway. I had an engineer machine up a new shaft and strengthen it. The gyro is a side by side encolosed with a EJ25 so she's not a light gyro. I've done approx 80 landings, so far no problems.
Cheers Paul

[RossM]

G001 had bushing seize, and veer of the runway did it not
also
part of a post by Mad Max posted years ago this

I rolled a gyro end over nose on take-off 20 yrs back after dropping nose wheel into a bulldust hole. Came out of the dust cloud pissed off and blaming...

[Tim]

G'day Allan, a very good query. I presume you are asking about any nose wheel failures, not just the strut types. have heard of many nose wheel failures over time, too numerous to remember. The most common failures were of the old Bensen style and clones with a U shaped aluminium bracket held onto the frame with a short 3/8" bolt and a anti friction disc between it and the keel (a circle cut out of the lid of a plastic icecream container). Those who replicated the bracket from steel to make it stronger usually made the problem worse and snapped the bolt or tore the keel instead of bending the bracket. The main culprit here was the pilot (as is more often than not the case) who insisted on using their machines as off-road buggies. I would assume that there would not be too many of these designs still flying.
I've heard of a few "long strut" failures, big bird designes or clones, at least one in Australia and one in the US. I think the US one hit a small ditch and the Aust one had a weld failure. I would be confident that there would have been more failures of this design that we don't know about. These were particularly dangerous because it meant an instant forward tumble.
There was also a design fault on the RAF 2000 nose wheel (pivot shaft I think) that bought a few unstuck.
Many more up to date designs incorporate suspension which alleviates much of the stress on the bracket and keel. The most common of these is what is commonly called the Rosco, and it's many copies. These would have undoubtedly knocked up the most hours in Australia. I am aware of one failure on an original when the AN 8 pivot bolt snapped. An unconfirmed report suggests that the gyro had done a lot of taxiing over rough country and that the bolt already had a slight bend and the breakage showed signs of crystalline fatigue.
Your own failure appeared to me to be a design fault and if I remember correctly Murray B fixed that problem.
I have no doubt that there should be a design standard for nose wheels, apart from the one already in the Standards which mandated roughly something like 1.5 times the required strength to effectively do the job (for any manufactured part in fact).
It would be a very hard one to formulate. I don't think too many builders would be too chuffed about driving their gyro at gross and at a predetermined speed, into a fixed object at nose wheel height to determine whether the wheel fails or not.

[aussie_paul]

I had a RAF 2000 nose wheel fail during landing as the nose wheel lowered and touched the ground when almost stopped. Design fault by RAF as they drilled a hole for a roll pin at exactly the incorrect spot. It could have been drilled in a much less stressed area and still done its job. The machine skidded along on the underside of the cab for a metre or so!!!

Aussie Paul.

[Waddles]

I would appear that the most common theme amongst most of the failures is rough ground and/or holes in the ground. The problem we are faced with is do we just warn members about the apparent dangers of rough field operations and hope they heed such warnings, or do we try to develop a formula and test for nose wheel strut strength? I'm referring specifically to the load imposed from the front to the rear of the strut assembly. There are many variables including the nose wheel size. There's also a thought that the larger the nose wheel diameter, the less the force may be imparted to the strut assembly. Does tyre pressure also come into it? There is much research going on into the theoretical forces that maybe present and all this takes time, even for a bunch of volunteers.

We think that a practical strength test would involve tethering the gyro by the main undercarriage forward, then attaching a manual winch to the nose wheel strut at say the axle point,then attaching a load cell to the end of the winch and then tether the load cell aft of the gyro. The load measured without strut assembly distortion or failure is what we are trying to determine.

There is a disappointing lack of reports in the incidents file which makes such research very tiresome. Had all the failures you guys have reported above been recorded officially, this thread would not be necessary. But, you can take a horse to water ......................

Thanks again for all the input so far. The fat lady hasn't sung yet!

Waddles

[chook]

Alan as you would be aware we recently had an in flight door separation occur with minimal damage to the aircraft and none to the occupants. My approach was to suggest a simple electric door alarm which will detect the position of the locking pins to prevent this from ever happening again. The design approach for a front wheel should probably follow the same philosophy. May I remind you that the front wheel assy on the Amax uses a trailing arm principle in which the front wheel initially absorbs the hole or bump in the runway via the front mounted spring. Further travel into a hole would be counter acted by deflection of the wheel .
I have attached a picture for clarity and note that this system would not be able to be tested using your methodology.

Regards.........Chook.

[RickE]

There was also a front wheel assembly broken at the ASRA Nats in Goolwa this year, mind you I think that front wheel went down a rabbit hole.

I think Allan that all members [myself included] need to realise the importance of reporting incidents even if relatively minor in order to create a data base of information from which safety and build standards can be developed.

[tonydenton]

I like that design chook [ strong ] the front mount is a sleeve so that even if the bolts did fall out or break the main keel is holding it .