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gregsmi
Joined: 01 Jan 2011
Posts: 268
Location: Topeka, KS
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 Posted: Thu Mar 28, 2013 10:05 am Post subject: Nose gear inspections |
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I have notice we are seeing some reports of nose gear failures. I know of three in the US and two in Europe. Recently we were able to recover all the parts and do an analysis. The results are inconclusive at this point, but what is known is the spindle shaft broke in fatigue. We do not know what started the cycle, hard landing, fast landing and hard braking, but at this point, we do know that it would be smart to include the nose gear in your inspection routine. This will involve you removing the fork and checking the spindle shaft. If it is not straight, it probably should be suspect and appropriate action taken.
Several people have designed new spindles, my self included. One is posted on the Yahoo group site pictures. I have been flying my Pulsar since 1996, 1400 hours, with no sign of a problem, but I have decided to replace the spindle with my own design I am having made out of one inch 4130 heat treated to 150KSI. I am doing this because the fatigue failures I have seen have happened up inside the collar where you cannot see, so the only detection is if the spindle is bent. I know, over the years I have flown my aircraft I have unintentionally bounced the nose so I decided to replace it now rather than risk the aircraft. For me, I hate cutting up a part that has served me so well for so many years, but I do not want to look back and say I suspected this might happen.
Now I know you tail dragger fans out there will have a field day with this, and that is OK, but please do take this note seriously. I do not want to read about anyone getting hurt because of a failure. These are experimental aircraft, and in the Pulsar case, totally without factory support, so it is up to the owner to decide what they should do. In most cases, you are the manufacture of the aircraft. I am taking a conservative approach and rebuilding mine in such a way that it is easily inspected and will be stronger than the original design.
Be safe.
Greg
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bernard.wilder2(at)gmail.
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| Posted: Thu Mar 28, 2013 10:17 am Post subject: Nose gear inspections |
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Greg,
Are the suspect nose gesrs the ones that Aero Design furnished, the ones from Sky Star, or both ? ? ? ?
Regards to you and Donna.
Bernie
On Thu, Mar 28, 2013 at 2:04 PM, <GREGSMI(at)aol.com (GREGSMI(at)aol.com)> wrote:
[quote] I have notice we are seeing some reports of nose gear failures. I know of three in the US and two in Europe. Recently we were able to recover all the parts and do an analysis. The results are inconclusive at this point, but what is known is the spindle shaft broke in fatigue. We do not know what started the cycle, hard landing, fast landing and hard braking, but at this point, we do know that it would be smart to include the nose gear in your inspection routine. This will involve you removing the fork and checking the spindle shaft. If it is not straight, it probably should be suspect and appropriate action taken.
Several people have designed new spindles, my self included. One is posted on the Yahoo group site pictures. I have been flying my Pulsar since 1996, 1400 hours, with no sign of a problem, but I have decided to replace the spindle with my own design I am having made out of one inch 4130 heat treated to 150KSI. I am doing this because the fatigue failures I have seen have happened up inside the collar where you cannot see, so the only detection is if the spindle is bent. I know, over the years I have flown my aircraft I have unintentionally bounced the nose so I decided to replace it now rather than risk the aircraft. For me, I hate cutting up a part that has served me so well for so many years, but I do not want to look back and say I suspected this might happen.
Now I know you tail dragger fans out there will have a field day with this, and that is OK, but please do take this note seriously. I do not want to read about anyone getting hurt because of a failure. These are experimental aircraft, and in the Pulsar case, totally without factory support, so it is up to the owner to decide what they should do. In most cases, you are the manufacture of the aircraft. I am taking a conservative approach and rebuilding mine in such a way that it is easily inspected and will be stronger than the original design.
Be safe.
Greg
| Quote: |
arget="_blank">http://www.matronics.com/Navigator?Pulsar-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
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[b]
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briana(at)xtra.co.nz
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| Posted: Thu Mar 28, 2013 11:56 am Post subject: Nose gear inspections |
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I'm interested in the effect of a modification I had to make to the nose gear leg before I completed my Pulsar. The original cast aluminium fork supplied in the kit had the pivot hole drilled on a slight angle, which resulted in a rather odd looking wheel tilt when the nose wheel was mounted. I ordered a replacement from Skystar, and by that time they had increased the diameter of the pivot, so the bushing in the casting was a larger size. I had a sleeve made to fit over the original pivot and this was heat shrunk into place. It's a long time ago, but I think the pivot is now 3/4" diameter, rather than the original 5/8" diameter. I think the whole casting was thicker too, which meant that I had to alter the arrangement of bell view washers to get an acceptable solution.
The result has performed well. I've probably done about 600 landings on seal and on grass [some pretty rough grass], and also on a rough strip in the mountains where the large round stones were hidden by long grass. Scary!!
Is it possible with this modification that the stresses in the spindle are a little less, leading to a longer fatigue life. Maybe - - - maybe not.
Brian
On 29/03/2013, at 7:04 AM, GREGSMI(at)aol.com (GREGSMI(at)aol.com) wrote:
[quote] I have notice we are seeing some reports of nose gear failures. I know of three in the US and two in Europe. Recently we were able to recover all the parts and do an analysis. The results are inconclusive at this point, but what is known is the spindle shaft broke in fatigue. We do not know what started the cycle, hard landing, fast landing and hard braking, but at this point, we do know that it would be smart to include the nose gear in your inspection routine. This will involve you removing the fork and checking the spindle shaft. If it is not straight, it probably should be suspect and appropriate action taken.
Several people have designed new spindles, my self included. One is posted on the Yahoo group site pictures. I have been flying my Pulsar since 1996, 1400 hours, with no sign of a problem, but I have decided to replace the spindle with my own design I am having made out of one inch 4130 heat treated to 150KSI. I am doing this because the fatigue failures I have seen have happened up inside the collar where you cannot see, so the only detection is if the spindle is bent. I know, over the years I have flown my aircraft I have unintentionally bounced the nose so I decided to replace it now rather than risk the aircraft. For me, I hate cutting up a part that has served me so well for so many years, but I do not want to look back and say I suspected this might happen.
Now I know you tail dragger fans out there will have a field day with this, and that is OK, but please do take this note seriously. I do not want to read about anyone getting hurt because of a failure. These are experimental aircraft, and in the Pulsar case, totally without factory support, so it is up to the owner to decide what they should do. In most cases, you are the manufacture of the aircraft. I am taking a conservative approach and rebuilding mine in such a way that it is easily inspected and will be stronger than the original design.
Be safe.
Greg
| Quote: |
href="http://www.matronics.com/Navigator?Pulsar-List">http://www.matronics.com/Navigator?Pulsar-List
href="http://forums.matronics.com/">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/contribution
|
[b]
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gregsmi
Joined: 01 Jan 2011
Posts: 268
Location: Topeka, KS
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| Posted: Thu Mar 28, 2013 1:17 pm Post subject: Nose gear inspections |
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The ones that cam from Aerodesigns are the ones I am dealing with. I suspect that the fatigue cracking is started by a single incident of overloading. After that, it slowly progresses until failure. But again, this is just speculation, only know for sure that the failures appear to progress over time.
Greg
In a message dated 3/28/2013 12:18:09 P.M. Central America Standard , bernard.wilder2(at)gmail.com writes:
| Quote: | Greg,
Are the suspect nose gesrs the ones that Aero Design furnished, the ones from Sky Star, or both ? ? ? ?
Regards to you and Donna.
Bernie
On Thu, Mar 28, 2013 at 2:04 PM, <GREGSMI(at)aol.com (GREGSMI(at)aol.com)> wrote:
| Quote: | I have notice we are seeing some reports of nose gear failures. I know of three in the US and two in Europe. Recently we were able to recover all the parts and do an analysis. The results are inconclusive at this point, but what is known is the spindle shaft broke in fatigue. We do not know what started the cycle, hard landing, fast landing and hard braking, but at this point, we do know that it would be smart to include the nose gear in your inspection routine. This will involve you removing the fork and checking the spindle shaft. If it is not straight, it probably should be suspect and appropriate action taken.
Several people have designed new spindles, my self included. One is posted on the Yahoo group site pictures. I have been flying my Pulsar since 1996, 1400 hours, with no sign of a problem, but I have decided to replace the spindle with my own design I am having made out of one inch 4130 heat treated to 150KSI. I am doing this because the fatigue failures I have seen have happened up inside the collar where you cannot see, so the only detection is if the spindle is bent. I know, over the years I have flown my aircraft I have unintentionally bounced the nose so I decided to replace it now rather than risk the aircraft. For me, I hate cutting up a part that has served me so well for so many years, but I do not want to look back and say I suspected this might happen.
Now I know you tail dragger fans out there will have a field day with this, and that is OK, but please do take this note seriously. I do not want to read about anyone getting hurt because of a failure. These are experimental aircraft, and in the Pulsar case, totally without factory support, so it is up to the owner to decide what they should do. In most cases, you are the manufacture of the aircraft. I am taking a conservative approach and rebuilding mine in such a way that it is easily inspected and will be stronger than the original design.
Be safe.
Greg
| Quote: |
arget="_blank">http://www.matronics.com/Navigator?Pulsar-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
|
ef="http://www.matronics.com/Navigator?Pulsar-List">http://www.matronics.com/Navigator?Pulsar-List
s.matronics.com/">http://forums.matronics.com
p://www.matronics.com/contribution">http://www.matronics.com/contribution
|
|
[quote][b]
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gregsmi
Joined: 01 Jan 2011
Posts: 268
Location: Topeka, KS
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| Posted: Thu Mar 28, 2013 1:45 pm Post subject: Nose gear inspections |
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Brian, the failures I have seen are, the 5/8 inch bolt shears inside the collar that is welded to the 1 inch strut. I do not think that has anything to do with the fork. Maybe it is absorbing more stress in the inserts, but really do not know.
The ones I have seen are the stock 5/8 inch spindle bolts failing inside the collar. If you have that arrangement, I would start checking it immediately just to make sure the bolt is not bent. Even then, I am not sure that is the only criteria for failure, but if it is bent, that is a sure sign it has been stressed beyond limits. Will it fail, I do not know because all the failures I have seen are up inside the collar. That is why I have decided to replace mine. I cannot see if there is any fatigue cracks.
I wish I could have more information but I have shared everything I know and what I am doing. I just hope that passing this information along gives everyone a new point to inspect and be safe.
Greg
In a message dated 3/28/2013 1:56:34 P.M. Central America Standard T, briana(at)xtra.co.nz writes:
| Quote: | I'm interested in the effect of a modification I had to make to the nose gear leg before I completed my Pulsar. The original cast aluminium fork supplied in the kit had the pivot hole drilled on a slight angle, which resulted in a rather odd looking wheel tilt when the nose wheel was mounted. I ordered a replacement from Skystar, and by that time they had increased the diameter of the pivot, so the bushing in the casting was a larger size. I had a sleeve made to fit over the original pivot and this was heat shrunk into place. It's a long time ago, but I think the pivot is now 3/4" diameter, rather than the original 5/8" diameter. I think the whole casting was thicker too, which meant that I had to alter the arrangement of bell view washers to get an acceptable solution.
The result has performed well. I've probably done about 600 landings on seal and on grass [some pretty rough grass], and also on a rough strip in the mountains where the large round stones were hidden by long grass. Scary!!
Is it possible with this modification that the stresses in the spindle are a little less, leading to a longer fatigue life. Maybe - - - maybe not.
Brian
On 29/03/2013, at 7:04 AM, GREGSMI(at)aol.com (GREGSMI(at)aol.com) wrote:
| Quote: | I have notice we are seeing some reports of nose gear failures. I know of three in the US and two in Europe. Recently we were able to recover all the parts and do an analysis. The results are inconclusive at this point, but what is known is the spindle shaft broke in fatigue. We do not know what started the cycle, hard landing, fast landing and hard braking, but at this point, we do know that it would be smart to include the nose gear in your inspection routine. This will involve you removing the fork and checking the spindle shaft. If it is not straight, it probably should be suspect and appropriate action taken.
Several people have designed new spindles, my self included. One is posted on the Yahoo group site pictures. I have been flying my Pulsar since 1996, 1400 hours, with no sign of a problem, but I have decided to replace the spindle with my own design I am having made out of one inch 4130 heat treated to 150KSI. I am doing this because the fatigue failures I have seen have happened up inside the collar where you cannot see, so the only detection is if the spindle is bent. I know, over the years I have flown my aircraft I have unintentionally bounced the nose so I decided to replace it now rather than risk the aircraft. For me, I hate cutting up a part that has served me so well for so many years, but I do not want to look back and say I suspected this might happen.
Now I know you tail dragger fans out there will have a field day with this, and that is OK, but please do take this note seriously. I do not want to read about anyone getting hurt because of a failure. These are experimental aircraft, and in the Pulsar case, totally without factory support, so it is up to the owner to decide what they should do. In most cases, you are the manufacture of the aircraft. I am taking a conservative approach and rebuilding mine in such a way that it is easily inspected and will be stronger than the original design.
Be safe.
Greg
| Quote: |
href="http://www.matronics.com/Navigator?Pulsar-List">http://www.matronics.com/Navigator?Pulsar-List
href="http://forums.matronics.com/">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/contribution
|
ef="http://www.matronics.com/Navigator?Pulsar-List">http://www.matronics.com/Navigator?Pulsar-List
s.matronics.com/">http://forums.matronics.com
p://www.matronics.com/contribution">http://www.matronics.com/contribution
|
|
[quote][b]
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grogolus(at)yahoo.com
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| Posted: Fri Mar 29, 2013 6:10 am Post subject: Nose gear inspections |
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greg, do you have any photos or drawing of you spindle shaft fix? thanks, bob
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