Sam Buchanan
been here awhile
I can't imagine what the liability exposure and public scrutiny would be for someone who offered an alternative nosegear design.
Van's Air Force
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RV-9A front gear folds
- Thread starter MrNomad
- Start date
I can't imagine what the liability exposure and public scrutiny would be for someone who offered an alternative nosegear design.
Hummm... it has been asked how many rv's have had problems with the landing gear on landing for the A's in the last year, so far no data. I seem to recall only 3, is this a problem, I don't think so. Is there more than 3??? I don't mean into a field. I'm talking actual runways.
I'm also seeing a sort of rebutal with words about the landing gear, mainly from people the have tail wheel airplanes, I hope that isn't their way of sending a message about nose wheel airplanes.
I'm also seeing a sort of rebutal with words about the landing gear, mainly from people the have tail wheel airplanes, I hope that isn't their way of sending a message about nose wheel airplanes.
L.Adamson
Well Known Member
With the additional weight on the Grumman torsion bar and brackets...............we'd have to settle for a wood prop and hand starting, 'cause a starter motor just weighs too much!
But seriously, when you get to the point of weighing these two seater airplanes, all that forward weight adds up! And when you see what the nose already weighs, the thought of adding more might not seem like such a great option. Grummans are not as quick and sporty as RV's, and the 10 is just much heavier altogether.
L.Adamson -- RV6A
brianwallis
VAF moderator
Adapt
If we could just figure out how to get the grumman nosegear on an RV then we would be set... It's the S-curve that does the trick. I've never seen a grumman dig in and go over.... maybe some have, but I'm not aware of any... and my yankee taxies fine anywhere I go... grass or paved.
Best
Brian
If we could just figure out how to get the grumman nosegear on an RV then we would be set... It's the S-curve that does the trick. I've never seen a grumman dig in and go over.... maybe some have, but I'm not aware of any... and my yankee taxies fine anywhere I go... grass or paved.
Best
Brian
Martin Sutter
Well Known Member
Some food for thought:
The wheel base on an A model RV is extremely short in comparison with the gear height. That means when the front gear collapses and the spinner hits the ground the aircraft is already quite vertical, the center of gravity high and a little forward momentum is all that is needed to complete the flip. That fact might contribute to the propensity to flip more than gear design. Look at a Grumman in comparison. Much longer wheel base and closer to the ground. If you draw a line from the top of the main gear to where the nose contacts the ground you will see that the angle of the fuselage is about half that of the RV. That might explain why RV's flip over frequently than other types AFTER the nose gear collapses.
The next question is - does the nose gear collapse more frequently than on other aircraft? I do not have a scientific answer to that but a look at the FAA's daily Accident and Incident reports http://www.faa.gov/data_statistics/accident_incident/preliminary_data/ shows that gear collapses and specifcally nose gear collapses are one of the most common types of accidents for all small aircraft.
A previous post listed many of the RV nose over accidents including pilot information. Did anyone note that the most of the pilots had under a hundred hours in type and many had low TT hours?
RV's are high performance airplanes by any standards. Like all high performance airplanes they require a bit more attention and precision in their operation than trainers. That is the price you pay for the pleasure to operate a nimble high performance machine. How many other high performance airplanes can you fly into bumpy grass strips? Could they be made sturdier? Of course but at the expense of performance. Could they be made easier and more forgiving to fly? Of course but at the price of performance. They do make machines like that, they are called Cherokee 140's, Cessna 152's and 172's.
Just food for thought.
Martin Sutter
building and flying RV's since 1988
The wheel base on an A model RV is extremely short in comparison with the gear height. That means when the front gear collapses and the spinner hits the ground the aircraft is already quite vertical, the center of gravity high and a little forward momentum is all that is needed to complete the flip. That fact might contribute to the propensity to flip more than gear design. Look at a Grumman in comparison. Much longer wheel base and closer to the ground. If you draw a line from the top of the main gear to where the nose contacts the ground you will see that the angle of the fuselage is about half that of the RV. That might explain why RV's flip over frequently than other types AFTER the nose gear collapses.
The next question is - does the nose gear collapse more frequently than on other aircraft? I do not have a scientific answer to that but a look at the FAA's daily Accident and Incident reports http://www.faa.gov/data_statistics/accident_incident/preliminary_data/ shows that gear collapses and specifcally nose gear collapses are one of the most common types of accidents for all small aircraft.
A previous post listed many of the RV nose over accidents including pilot information. Did anyone note that the most of the pilots had under a hundred hours in type and many had low TT hours?
RV's are high performance airplanes by any standards. Like all high performance airplanes they require a bit more attention and precision in their operation than trainers. That is the price you pay for the pleasure to operate a nimble high performance machine. How many other high performance airplanes can you fly into bumpy grass strips? Could they be made sturdier? Of course but at the expense of performance. Could they be made easier and more forgiving to fly? Of course but at the price of performance. They do make machines like that, they are called Cherokee 140's, Cessna 152's and 172's.
Just food for thought.
Martin Sutter
building and flying RV's since 1988
Other than the fact that it won't fit............
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i've been watching this post for the last couple of weeks with interest as I'm building an RV6A with this troublesome nose gear, It would be great to have something that can handle a bit of a whack . I do most of my flying in tecnam LSA 's and it is drilled into us from the start to get the nose of the ground as soon as the elevators will allow (about 35-40knots) and to keep the nose of the ground as long as possible. While I'm not by any stretch an accomplished pilot I would expect that if I don't treat the AC properly then it will fail at some point. A lot of ultralights and LSA aircraft require a gentle hand or they'll bight you, I expect to be very gentle with my 6A when the day comes ,i won't be avoiding grass strips but I will be very aware of what the AC is telling me ,and hopefully I'll never have to post something about bending my plane. cheers all Mat
az_gila
Well Known Member
More food for thought...
Martin.. not a really good comparison.
The searchable database is here....
http://www.ntsb.gov/ntsb/query.asp
I searched for the text "collapse" on all Experimentals in the data base for the last 5 years.
There were 28 "hits"
For 2 the word "collapse" was not associated with the gear (oil hose, hangar door)
11 were retractables - so they don't really count in this discussion...
6 were tail draggers
2 were nose gear airplanes, but had main gear collapses (no RVs)
That leaves 7 fixed nose gear collapses
5 RVs (three -6As, one each -7A and -9A)
2 Glastars
The RV list also includes the one that set off the FAA study
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20051006X01588&key=1
Of the tail draggers listed, only one was an RV type (a Harmon Rocket)
I read this to say that the RVs are the most popular homebuilt, and the -A models are heavily represented in nose gear collapses of Experimentals, but YMMV.
Note that I took certified planes out of the search.
...just some more food for thought....
To complete... for the retractables
Only one was a nose gear collapse
1 was all three gear
The other 7 were main gear collapses
Martin.. not a really good comparison.
The searchable database is here....
http://www.ntsb.gov/ntsb/query.asp
I searched for the text "collapse" on all Experimentals in the data base for the last 5 years.
There were 28 "hits"
For 2 the word "collapse" was not associated with the gear (oil hose, hangar door)
11 were retractables - so they don't really count in this discussion...
6 were tail draggers
2 were nose gear airplanes, but had main gear collapses (no RVs)
That leaves 7 fixed nose gear collapses
5 RVs (three -6As, one each -7A and -9A)
2 Glastars
The RV list also includes the one that set off the FAA study
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20051006X01588&key=1
Of the tail draggers listed, only one was an RV type (a Harmon Rocket)
I read this to say that the RVs are the most popular homebuilt, and the -A models are heavily represented in nose gear collapses of Experimentals, but YMMV.
Note that I took certified planes out of the search.
...just some more food for thought....
To complete... for the retractables
Only one was a nose gear collapse
1 was all three gear
The other 7 were main gear collapses
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Martin Sutter
Well Known Member
Good point Gil. I just wanted to point out that gear collapses of all types are quite common for certified and experimental airplanes and as the previous poster pointed out they are turning out to be an issue with LSA's too.
Martin Sutter
building and flying RV's since 1988
Martin Sutter
building and flying RV's since 1988
number of gear failures
After reading the posts which list the accidents and causes it strikes me that there is less of a problem with the nose gear than I first thought. Given the thousands and thousands of landings by A's on varying types of surfaces, I would think that if there was a nose gear issue of any significance there would be far greater numbers of failures. Many of the nose gear failures, and there are just a very small number of them, seem to be attributable to a pilot induced problem, ie. hard landing, hard three point landing, off airport landing, etc. There only appear to be three where the operators indicated they were performing properly and the nose gear caused a problem. Those were the collapse of the gear when going over a runway transition area (which started this whole thread), the Palmer alaska incident, and one where the operator was taxing and the nose gear did some damage. Maybe a bad landing should not be the cause of a nose gear problem, but it is hard to tell from the reports how bad the landing was. Just how serious is this problem?
After reading the posts which list the accidents and causes it strikes me that there is less of a problem with the nose gear than I first thought. Given the thousands and thousands of landings by A's on varying types of surfaces, I would think that if there was a nose gear issue of any significance there would be far greater numbers of failures. Many of the nose gear failures, and there are just a very small number of them, seem to be attributable to a pilot induced problem, ie. hard landing, hard three point landing, off airport landing, etc. There only appear to be three where the operators indicated they were performing properly and the nose gear caused a problem. Those were the collapse of the gear when going over a runway transition area (which started this whole thread), the Palmer alaska incident, and one where the operator was taxing and the nose gear did some damage. Maybe a bad landing should not be the cause of a nose gear problem, but it is hard to tell from the reports how bad the landing was. Just how serious is this problem?
az_gila
Well Known Member
A few more....
The FAA report that set off the analysis listed quite a few more than you did - the link was referenced in a previous post...
Four of the accidents and one incident involved a touchdown and the start of a rollout on an unpaved runway, followed by the nose gear folding back. The airplanes would then slide for varying distances before nosing over. Staff also examined data for four additional incidents in which the nose gear collapsed during taxi but the airplane did not nose over. These nine accidents and incidents occurred on various unpaved surfaces including gravel, turf, soft turf, hard surface with "washboard" bumps, and slight depressions, and they all involved the nose gear strut and fork digging into the ground and the nose gear bending aft.
....and there seem to be a few more of the "taxi along" type referenced on VAF that probably did not make the NTSB accident/incident data base.
Serious or not? - you decide....
The FAA report that set off the analysis listed quite a few more than you did - the link was referenced in a previous post...
Four of the accidents and one incident involved a touchdown and the start of a rollout on an unpaved runway, followed by the nose gear folding back. The airplanes would then slide for varying distances before nosing over. Staff also examined data for four additional incidents in which the nose gear collapsed during taxi but the airplane did not nose over. These nine accidents and incidents occurred on various unpaved surfaces including gravel, turf, soft turf, hard surface with "washboard" bumps, and slight depressions, and they all involved the nose gear strut and fork digging into the ground and the nose gear bending aft.
....and there seem to be a few more of the "taxi along" type referenced on VAF that probably did not make the NTSB accident/incident data base.
Serious or not? - you decide....
number of incidents of nose gear damage
Thanks for the info. I read that report and while it refers to a total of five times there was some damage, I could not verify those accounts except for the ones I referred to in my earlier post. For the person who suffers the damage it surely is a serious event, but I am confident that given the very few numbers involved against the thousands of taxi and landing events that statistically it is is not very significant. Take Cessna nose gear aircraft over the same number of landing on similar terrain, and I would wager that there were more nose gear related damage events than with the A's. For the pilots who had what they report to be damage caused for reasons beyond their control, I imagine that they view this as a very serious problem that Vans or someone else is responsible for. I choose sometimes to believe in serendipity, S--- sometimes happens for no apparent reason. But realistically there generally is a reason. And the last reason I and most others wish to acknowlege is that we contributed to the event in an adverse way. This is not meant to cast blame in any way but merely point to another logical ,if not readily acceptable, answer to WHY. As for me, I will put the new fork on and use all the components that came with the kit to mount the wheel to the new fork as before, with the same break out force and same tightness, and keep the tire pressure at 40 to 45#s. I will be very diligent in landing on the mains first and allowing the nose to lower in a smooth and low speed both on paved and nonpaved runways. I will taxi slow and will take all ridges or bumps even slower and at an angle with the stick back. And I will endeavor to load the plane towards theback side of the envelope when I can. And finally I want to be lucky if I screw up in any way.
Thanks for the info. I read that report and while it refers to a total of five times there was some damage, I could not verify those accounts except for the ones I referred to in my earlier post. For the person who suffers the damage it surely is a serious event, but I am confident that given the very few numbers involved against the thousands of taxi and landing events that statistically it is is not very significant. Take Cessna nose gear aircraft over the same number of landing on similar terrain, and I would wager that there were more nose gear related damage events than with the A's. For the pilots who had what they report to be damage caused for reasons beyond their control, I imagine that they view this as a very serious problem that Vans or someone else is responsible for. I choose sometimes to believe in serendipity, S--- sometimes happens for no apparent reason. But realistically there generally is a reason. And the last reason I and most others wish to acknowlege is that we contributed to the event in an adverse way. This is not meant to cast blame in any way but merely point to another logical ,if not readily acceptable, answer to WHY. As for me, I will put the new fork on and use all the components that came with the kit to mount the wheel to the new fork as before, with the same break out force and same tightness, and keep the tire pressure at 40 to 45#s. I will be very diligent in landing on the mains first and allowing the nose to lower in a smooth and low speed both on paved and nonpaved runways. I will taxi slow and will take all ridges or bumps even slower and at an angle with the stick back. And I will endeavor to load the plane towards theback side of the envelope when I can. And finally I want to be lucky if I screw up in any way.
az_gila
Well Known Member
Cessnas and nose gears...
Good point... so I did...
A data base search over the same five years for "nose" and "collapse" for all Cessna products produced 65 hits.
After the retractable Cessnas were removed, the list is 36 long.
Given that the Cessna reports highlighted students a lot, and also included the off airfield, hit culvert/runway sign, etc type accidents... and given that there are a h#@* of a lot more fixed gear Cessnas out there that RVs, I think RVs are over represented... but again, YMMV.
I sampled over half of the reports, and none happened while taxying.
FWIW Cessna made over 75,000 C-172, C-150, C-152 planes, and a lot stayed in the US.... ...and we are comparing numbers to Vans "A" models only.
Good point... so I did...
A data base search over the same five years for "nose" and "collapse" for all Cessna products produced 65 hits.
After the retractable Cessnas were removed, the list is 36 long.
Given that the Cessna reports highlighted students a lot, and also included the off airfield, hit culvert/runway sign, etc type accidents... and given that there are a h#@* of a lot more fixed gear Cessnas out there that RVs, I think RVs are over represented... but again, YMMV.
I sampled over half of the reports, and none happened while taxying.
FWIW Cessna made over 75,000 C-172, C-150, C-152 planes, and a lot stayed in the US....
...and we are comparing numbers to Vans "A" models only.Captain Avgas
Well Known Member
In addition the FAA report dealt only with nose gear failures in the US....but there have been many failures overseas as well.
In Australia a few years back an RV suffered a nose gear collapse on a take-off roll on a sealed surface runway with zero imperfections. The resultant damage was extensive. The gear was sent back to Vans who tested it and ascertained that it had been properly heat treated.
Vans concluded that the builder had the nose wheel fairing too close to the tire...that specific incident led to a recommendation by Vans for builders to provide more generous clearance.
However it was interesting that in due course the FAA report suggested that the tight wheel fairing theory was largely erroneous. It stated that there would be insufficient drag caused by the composite fairing coming into contact with the tire to cause the nose gear to collapse.
Good point... so I did...
A data base search over the same five years for "nose" and "collapse" for all Cessna products produced 65 hits.
After the retractable Cessnas were removed, the list is 36 long.
Given that the Cessna reports highlighted students a lot, and also included the off airfield, hit culvert/runway sign, etc type accidents... and given that there are a h#@* of a lot more fixed gear Cessnas out there that RVs, I think RVs are over represented... but again, YMMV.
I sampled over half of the reports, and none happened while taxying.
FWIW Cessna made over 75,000 C-172, C-150, C-152 planes, and a lot stayed in the US....
Perhaps now you can see why statistics collected by us armchair quarterbacks are almost useless. You see, Gil searched for what he though he wanted - and he got exactly that. The problem is that the FAA is far from standard in their reporting. Some inspectors will call the nosewheel a nosegear, some put spaces between the "nose" and "wheel" or "nose" and "gear", etc.. Then, some use the word collapse, and some say collapsed, some say failed, fail, failure, broke, bent, retracted, etc..
The point is Gil got EXACTLY what he was looking for - no less and no more. Those of you who know databases know they do exactly what you ask of them, no more and no less.
So, if you take Gil's search and add a wildard (*) to the end of 'Nose' and 'Collapse' the result balloons from 65 results to 267 results. If you then throw in "fail" with a wildcard (*) along with 'nose' and 'collapse' or 'fail', the results balloon to 1541 results.
The search could go on and on with various results, but my point is that it's nearly impossible for us laymen to get a really accurate idea of comparable failures without a good reporting tool.
What I'm trying to say is that 90% of statistics can be make to say exactly what you want 50% of the time, depending on how you go about deriving your set of parameters and results. For example, if you leave the same search Gil did with "nose" and "collapse", then remove Cessna and tell it to show you ALL experimentals with those two words in the result, you get a total of 10 records..., but if you add the wildcards back into the search, you now get 56 records for ALL experimentals verses the 267 results for the same period/terms/criteria for "cessna". Add Piper, you get more. Change the search to "air carrier" and you get 12 records. Do the search for "General Aviation" and you get 548 records for non experimental and 56 for "amateur built" without changing any other parameters.
If you are trying to get an apples to apples comparision, run some of the above scenarios and you'll see that experimentals as whole are about 10 times less likely to show up in a search with the terms "nose" and "collapse" then certificated General Aviation planes....at least based on those search parameters - what does that tell us?!?! Depends on what you're searching for!
Take all the statistics for what they are - no more and no less. Sorry for the rant.
My 2 cents as usual.
Cheers,
Stein.
My own research indicates that precisely 23.64% of statistics are made up on the spot.
My own research indicates that precisely 23.64% of statistics are made up on the spot.
I always liked the phrase, "Figures don't lie, but liars do figure." (Of course not aimed at anyone on this forum!)
Bob Kelly
az_gila
Well Known Member
Bad search text...
Stein's rant is partially correct....
I did make an error, and should have wild-carded the "collapse" as "collaps*" to get the words collapse/collapses/collapsed also included. "nose" is OK and consistent in the FAA reports.
This does give the 267 results, and when the retractables (and nose gear ones) are removed around 150 to 160 hits. A sampling of the actual reports, which is really needed for a good analysis, and can be performed. My quick sample showed hard, bounced landings at high speed and collisions with obstructions as most prevalent.
A much more interesting search for the purposes of this discussion was "nose" and "tax*" to see if any Cessnas had nose gear accidents/incidents in the taxi phase... there were 5 fixed gear hits, but when each report was read, only one happened while taxiing, and he was flipped over by a thunderstorm!!
I still contend that our RV -A models have more problems in the taxi phase (which may or may not extend to runway operations - you judge) than certified planes.
Sorry for the initial text search error... thanks for the correction Stein...
gil A
Stein's rant is partially correct....
I did make an error, and should have wild-carded the "collapse" as "collaps*" to get the words collapse/collapses/collapsed also included. "nose" is OK and consistent in the FAA reports.
This does give the 267 results, and when the retractables (and nose gear ones) are removed around 150 to 160 hits. A sampling of the actual reports, which is really needed for a good analysis, and can be performed. My quick sample showed hard, bounced landings at high speed and collisions with obstructions as most prevalent.
A much more interesting search for the purposes of this discussion was "nose" and "tax*" to see if any Cessnas had nose gear accidents/incidents in the taxi phase... there were 5 fixed gear hits, but when each report was read, only one happened while taxiing, and he was flipped over by a thunderstorm!!
I still contend that our RV -A models have more problems in the taxi phase (which may or may not extend to runway operations - you judge) than certified planes.
Sorry for the initial text search error... thanks for the correction Stein...
gil A
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John C
Well Known Member
other defining words
Try looking at "inverted", "nose over", "noseover", etc. From those searchs and the ones suggested by Gil and Stein, read the briefs and sort out those that are not of interest and the multiple hits. With multiple work searchs, the order is also important. "invereted" first or last may give different results.
Try looking at "inverted", "nose over", "noseover", etc. From those searchs and the ones suggested by Gil and Stein, read the briefs and sort out those that are not of interest and the multiple hits. With multiple work searchs, the order is also important. "invereted" first or last may give different results.
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numbers
Maybe the A's are over represented, maybe they are not. It's close, I think that we would all agree on that. If so, again, I wonder why the big concern about the A's nose gear. Is it defective? Or is it not? Do the numbers give us an answer? Probably not, in my opinion. But to be on the safe side I will be extra careful when I taxi and land my 180 HP 9A. By the way, I have lived in Alaska for over fourty years and know that there are a large, large number of occasions where Cessna nose gears have parted ways with the rest of the airplane and not gotten reported. Taxing and landing on lots of different surfaces and turning on soft terrain have often resulted in nose gear collapse. Who is responsible in these cases?
Maybe the A's are over represented, maybe they are not. It's close, I think that we would all agree on that. If so, again, I wonder why the big concern about the A's nose gear. Is it defective? Or is it not? Do the numbers give us an answer? Probably not, in my opinion. But to be on the safe side I will be extra careful when I taxi and land my 180 HP 9A. By the way, I have lived in Alaska for over fourty years and know that there are a large, large number of occasions where Cessna nose gears have parted ways with the rest of the airplane and not gotten reported. Taxing and landing on lots of different surfaces and turning on soft terrain have often resulted in nose gear collapse. Who is responsible in these cases?
az_gila
Well Known Member
Not in this data base...
It appears that this data base is a straight AND function of the words chosen
"nose" and "collapse" as a search function gets the same number of hits as "collapse" and "nose" - just like the Help function says.
Note that my searches looked for both words occuring anywhere in the reports, not a string identical to "nose collapse", but as Stein said, I should have wildcarded better....
It appears that this data base is a straight AND function of the words chosen
"nose" and "collapse" as a search function gets the same number of hits as "collapse" and "nose" - just like the Help function says.
Note that my searches looked for both words occuring anywhere in the reports, not a string identical to "nose collapse", but as Stein said, I should have wildcarded better....
rjcthree
Well Known Member
Possible discussion
I may have an opportunity to have a brief discussion with the author of the NTSB ANC05LA123 structures report. If it happens, I'd like the group's thoughts on what questions we might like to see asked.
Understand the answers will most likely be verbal, and it will be 'for information only'.
Thoughts?
Rick 90432 Fuse eyeballing finishing kit - and trying to create a one-pc tail fairing from what Bob shipped me. . . .
I may have an opportunity to have a brief discussion with the author of the NTSB ANC05LA123 structures report. If it happens, I'd like the group's thoughts on what questions we might like to see asked.
Understand the answers will most likely be verbal, and it will be 'for information only'.
Thoughts?
Rick 90432 Fuse eyeballing finishing kit - and trying to create a one-pc tail fairing from what Bob shipped me. . . .
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AlexPeterson
Well Known Member
Yes
1. Nose gear dynamics were not studied - I believe their FEA was a static loading situation only.
2. Wheel bearing drag as it may or may not relate to the fork structure deflecting/oscillating. I.e., feedback loop on bearing drag and misalignment.
3. Wheel bearing design - which type, solid axle or "mushroom" design?
4. Why were 6A's so under represented in the accident type, when there are so many more of them? May relate to #3. Seems like an obvious question, but wasn't addressed in the report.
Thanks!
GrayHawk
Well Known Member
Maybe ask about possibility of getting any/all data they have so we can start populating a more complete data set; and then maintain it forward. There are ways to visualize this data to highlight potential problems.
As for the 6A Vs. 7A,8A,9A; there may be two differences: 1) the wheel bearing change (what Alex is talking about) 2) The higher CG position on the ground (longer main gear legs).
As for the 6A Vs. 7A,8A,9A; there may be two differences: 1) the wheel bearing change (what Alex is talking about) 2) The higher CG position on the ground (longer main gear legs).
Little_Richard
Active Member
Has the testing been completed on the failed gear leg?
Has the metallurgy and hardness testing been completed on the 9A gear leg that started this whole thread? I am interested in what the results show.
Has the metallurgy and hardness testing been completed on the 9A gear leg that started this whole thread? I am interested in what the results show.
az_gila
Well Known Member
I asked the same thing...
...today from the owner.
It's still in process at a facility in Tucson.
gil A - in Burlington, IA
...today from the owner.
It's still in process at a facility in Tucson.
gil A - in Burlington, IA
Bryan Wood
Well Known Member
1G
I just read back thru the NTSB report on A flip overs again to make sure that I'm not mis-stating this. This isn't to get the debate heated again, just a way of looking at this that I don't think everybody is getting yet. When I read the report originally this didn't jump out at me, but after speaking with somebody at the NTSB about the report the following was pointed out. They appied a force to a gear leg to check for the thresholds of flexing, or when taken to the extreme, bending. The force is listed on the report between 1000 and 2000 pounds. The actual force that brought on dramatic flexing was around 1600-1700 pounds, so if you think about your airplanes weight it is right at 1G. Effectively any forward motion of the plane loaded with people and gas makes the plane heavy enough and can put the gear leg into the realm where it becomes "Elastic." My impression from the conversation is that the leg goes from strong and springy to spongy with around 1700 pounds of force put to it.
I would like to see you take the conversation in this direction and see if you come away with the same understanding as I did. This, as explained to me is why the little things that we can control such as tire pressure, stick back on landing and taxi, and light engine and propeller choices can help us in the end.
Really, hit on the change that occurs to the leg with 1G's worth of force. In order to enjoy our planes and minimize risk it is first going to take understanding. As Clint Eastwood said in one of his movies, "A mans gotta know his limitations."
I just read back thru the NTSB report on A flip overs again to make sure that I'm not mis-stating this. This isn't to get the debate heated again, just a way of looking at this that I don't think everybody is getting yet. When I read the report originally this didn't jump out at me, but after speaking with somebody at the NTSB about the report the following was pointed out. They appied a force to a gear leg to check for the thresholds of flexing, or when taken to the extreme, bending. The force is listed on the report between 1000 and 2000 pounds. The actual force that brought on dramatic flexing was around 1600-1700 pounds, so if you think about your airplanes weight it is right at 1G. Effectively any forward motion of the plane loaded with people and gas makes the plane heavy enough and can put the gear leg into the realm where it becomes "Elastic." My impression from the conversation is that the leg goes from strong and springy to spongy with around 1700 pounds of force put to it.
I would like to see you take the conversation in this direction and see if you come away with the same understanding as I did. This, as explained to me is why the little things that we can control such as tire pressure, stick back on landing and taxi, and light engine and propeller choices can help us in the end.
Really, hit on the change that occurs to the leg with 1G's worth of force. In order to enjoy our planes and minimize risk it is first going to take understanding. As Clint Eastwood said in one of his movies, "A mans gotta know his limitations."
Little_Richard
Active Member
It has been another week, any results on the hardness testing?
It has been another week, any results on the hardness testing? I was hoping to see some results as if the hardness was correct or not. I thought it was supposed to be done two weeks ago, but have not seen anything.
It has been another week, any results on the hardness testing? I was hoping to see some results as if the hardness was correct or not. I thought it was supposed to be done two weeks ago, but have not seen anything.
WHich also puts in another statement, the front wheel is a kick stand, should NOT be landed on. I'm sure these people that folded their front said, I didn't land on the front wheel, this time. I'm sure landing on it in the past DOES weakn' the thing. Be careful out there and land nose high. Which does bring up another problem, scuffing the rudder on landing. With many hours in tail wheel I'm sure I'll be dragging the rudder. I think I'll build a little wheel to screw in the rear tie down, just to protect the rudder.
N941WR
Legacy Member
Just leave the tie-down-ring in place. It is easy enough to replace every so often.
Of course, I already have a little wheel in the rear to protect the rudder.
Any Test results yet????????
MrNomad
Well Known Member
557BD is back in the air!! Yippee!!
After 64 consecutive twelve hour days, 557BD is back in the air. I circled the field yesterday for 30 minutes and then landed to de-cowl and inspect.
I was, quite literally, high as a kite for the rest of the day. The Catalina Mountains were splendid to view from the air (once again).
CHANGES: The front wheel pant was on (never leave home w/o it) and is fully reinforced on the inside with many layers of fiberglass. Thanks to Mel and Roger for their input.
The front wheel spins freely thanks to the internal, custom machined, steel spacer between the biscuits. In other words, despite torque and deflection from load, the front wheel will spin freely. During taxi tests, fore/aft front gear deflection was much less than ever before. We did not stake the biscuits.
After lots of discussion, emails, and input from others, we did not add any stiffeners to the front gear.
According to Paul Merems, the old front gear was hardened according to spec despite my ability to bend it back with a pipe wrench. Thanks Paul.
Breakout will be checked every 25 hours. The wife treated me to my very own scale (wow!!) so I don't have to borrow Gil's. She still refuses to fly, however.
Tire pressure will NEVER be lower than 35 lbs front.
Pockmarked runways will NEVER be landed on by choice. After this expensive episode, I'll leave adventure & grass fields to others. I'm too old for adventure.
Repairs included replacement gear, crankshaft, bearings, gaskets, prop straightening, and lots of help from Chet. If everyone had a friend like Chet, the world would be a much better place. To those unfortunate few who had the temerity to send nasty grams, learn from Chet and the world will be a better place.
We also addressed improvements to fuel flow, cooling, wiring changes, and lots more. It's amazing how much less time it takes to assemble an airplane the second time around. Thanks to Mike J for helping me assemble the Superior engine (again).
Warner Prop did a great job and went the extra mile so we didn't have to replace the Sensenich Prop. They even painted the tips yellow to match the airplane. Aircraft Specialties was also a first rate place to deal with concerning the replacement crankshaft. Ditto for good prices from Air Power on bearings & gaskets. Aguila in Chandler AZ was particularly helpful with magnaflux (check for cracks) & Chuck at Aircraft Engine Specialists in Chandler was a great guy to work with. He helped us split the case and inspect internal engine parts.
Thanks for all of the help and encouragement from people I have never met. Speaking from experience, one goes thru fits of rage (I don't break things, I FIX things), followed by simmering anger, then depression, then you settle in and just do it. It helps to have a great wife (39 years), good friends, and a window a/c in the shop.
Barry
Tucson RV9A, O-360, Dynon 180 & 100, SL30, 327, ICOM, F/P Sensenich
After 64 consecutive twelve hour days, 557BD is back in the air. I circled the field yesterday for 30 minutes and then landed to de-cowl and inspect.
I was, quite literally, high as a kite for the rest of the day. The Catalina Mountains were splendid to view from the air (once again).
CHANGES: The front wheel pant was on (never leave home w/o it) and is fully reinforced on the inside with many layers of fiberglass. Thanks to Mel and Roger for their input.
The front wheel spins freely thanks to the internal, custom machined, steel spacer between the biscuits. In other words, despite torque and deflection from load, the front wheel will spin freely. During taxi tests, fore/aft front gear deflection was much less than ever before. We did not stake the biscuits.
After lots of discussion, emails, and input from others, we did not add any stiffeners to the front gear.
According to Paul Merems, the old front gear was hardened according to spec despite my ability to bend it back with a pipe wrench. Thanks Paul.
Breakout will be checked every 25 hours. The wife treated me to my very own scale (wow!!) so I don't have to borrow Gil's. She still refuses to fly, however.
Tire pressure will NEVER be lower than 35 lbs front.
Pockmarked runways will NEVER be landed on by choice. After this expensive episode, I'll leave adventure & grass fields to others. I'm too old for adventure.
Repairs included replacement gear, crankshaft, bearings, gaskets, prop straightening, and lots of help from Chet. If everyone had a friend like Chet, the world would be a much better place. To those unfortunate few who had the temerity to send nasty grams, learn from Chet and the world will be a better place.
We also addressed improvements to fuel flow, cooling, wiring changes, and lots more. It's amazing how much less time it takes to assemble an airplane the second time around. Thanks to Mike J for helping me assemble the Superior engine (again).
Warner Prop did a great job and went the extra mile so we didn't have to replace the Sensenich Prop. They even painted the tips yellow to match the airplane. Aircraft Specialties was also a first rate place to deal with concerning the replacement crankshaft. Ditto for good prices from Air Power on bearings & gaskets. Aguila in Chandler AZ was particularly helpful with magnaflux (check for cracks) & Chuck at Aircraft Engine Specialists in Chandler was a great guy to work with. He helped us split the case and inspect internal engine parts.
Thanks for all of the help and encouragement from people I have never met. Speaking from experience, one goes thru fits of rage (I don't break things, I FIX things), followed by simmering anger, then depression, then you settle in and just do it. It helps to have a great wife (39 years), good friends, and a window a/c in the shop.
Barry
Tucson RV9A, O-360, Dynon 180 & 100, SL30, 327, ICOM, F/P Sensenich
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Congratulations Barry, and welcome back into the air!!
Paul
Paul
Just leave the tie-down-ring in place. It is easy enough to replace every so often.
Of course, I already have a little wheel in the rear to protect the rudder.
True on a 6a, not so with the 7a with the bigger rudder, you will hit the bottom of the rudder if you land too nose high.
wings05rv6a
Active Member
Gear Leg folding
Barry;
I am so GLAD that you and your wife are O.K. You sure did not diserve this.
I will help in any way to get you flying. Just let me know when and where and I will be there.
I have concerns about the desing of the front leg and would liketo know if anyone out there has any ideas on making it stronger. Rasing the tire further off of the ground. Changing the angle of the fork. and reinforsing the leg itself. Add a front ski to avoid the digging to the ground.
I would like to do all four.
In drawing #62 it shows a cross section where a damper was added by wraping both the leg and a piece of wood with fiber glass. That gave me an idea. If we could select the proper material that would be flexible and strong and wrap it with several layers of carbon fiber to reducethe spring affect. I wonder if this could work.
I am going to try, and post photos with progress.
I would also like to hear from anyone who has made modififications to their leg and post photos.
People have worked to hard on their planes to have this happen to them. We have a responsibility here, to make a change before someone die's.
Bob Wieczorek
allmost flying RV6a
Barry;
I am so GLAD that you and your wife are O.K. You sure did not diserve this.
I will help in any way to get you flying. Just let me know when and where and I will be there.
I have concerns about the desing of the front leg and would liketo know if anyone out there has any ideas on making it stronger. Rasing the tire further off of the ground. Changing the angle of the fork. and reinforsing the leg itself. Add a front ski to avoid the digging to the ground.
I would like to do all four.
In drawing #62 it shows a cross section where a damper was added by wraping both the leg and a piece of wood with fiber glass. That gave me an idea. If we could select the proper material that would be flexible and strong and wrap it with several layers of carbon fiber to reducethe spring affect. I wonder if this could work.
I am going to try, and post photos with progress.
I would also like to hear from anyone who has made modififications to their leg and post photos.
People have worked to hard on their planes to have this happen to them. We have a responsibility here, to make a change before someone die's.
Bob Wieczorek
allmost flying RV6a
AZtailwind
Well Known Member
Again, down right impressive!
Congratulations Barry
Congratulations Barry
rjcthree
Well Known Member
Grove & tire size
I recently talked to, and rec'd my Grove nosewheel. Funny, seems like they are selling all they can make - we're buying them up in lots of 50 in about 2 weeks(?!). It is a much nicer piece of hardware than the Matco.
What size tire is everybody putting on theirs? The Matco is a 5(dia)x4(wide), the Grove a 5x5. Pesonally, I intend on sending the chinese thing back to Vans anyway, but want to make sure I get the right one!
Thanks,
Rick 90432 -9a tip up - still fitting canopy. Big cut done, side fitting tonight.
I recently talked to, and rec'd my Grove nosewheel. Funny, seems like they are selling all they can make - we're buying them up in lots of 50 in about 2 weeks(?!). It is a much nicer piece of hardware than the Matco.
What size tire is everybody putting on theirs? The Matco is a 5(dia)x4(wide), the Grove a 5x5. Pesonally, I intend on sending the chinese thing back to Vans anyway, but want to make sure I get the right one!
Thanks,
Rick 90432 -9a tip up - still fitting canopy. Big cut done, side fitting tonight.
db1yg
Well Known Member
Hi Rick,
Good luck on finding another tire to fit your nose wheel. I also changed to a Grove nose wheel assembly and wanted to also go with a better quality nose tire. Unfortunately at the time I was looking the ONLY tire available was the Chinese "lamb" style tire--which you could buy from Desser or Vans. This is the same one that comes with Vans kit. Let us know if you find a better one.
On a positive note, after installing the Grove ALL of my shimmy is gone!! After many prior attempts to eliminate the shimmy, I have to conclude that the problem was due to the bearing preload/rolling resistance on the original Matco setting up a front to rear flexing movement of the gear leg. YMMV.
Cheers,
db
Good luck on finding another tire to fit your nose wheel. I also changed to a Grove nose wheel assembly and wanted to also go with a better quality nose tire. Unfortunately at the time I was looking the ONLY tire available was the Chinese "lamb" style tire--which you could buy from Desser or Vans. This is the same one that comes with Vans kit. Let us know if you find a better one.
On a positive note, after installing the Grove ALL of my shimmy is gone!! After many prior attempts to eliminate the shimmy, I have to conclude that the problem was due to the bearing preload/rolling resistance on the original Matco setting up a front to rear flexing movement of the gear leg. YMMV.
Cheers,
db
n2prise
Well Known Member
RV-9A tail tie down vs. rudder clearance.
One of the tests I made before my first flight was to be sure my tail tie down eyebolt hit the deck before the lower rudder cap with the main wheels on the hangar floor. I bought it at a local hardware store. It has a longer shank than the popular drop-forged closed ring tie-down bolts. It has only been field tested one time when a friend and I both put a foot on the steps at the same time and started to climb up on the wing. This photo was taken the day we made the "test" of the eyebolt. Look carefully and you will see the eyebolt extends at least one inch below the skin of the fuselage.
You may get a better view of the tail tie down eyebolt via this photo.
When I was student pilot flying a Cessna 172 and learning how to land, I managed to over-rotate in the flare in ground effect and drag the tie-down bolt without any other part of the airplane touching the ground first.
Since then, nothing but wheels touch the ground when I fly.
One of the tests I made before my first flight was to be sure my tail tie down eyebolt hit the deck before the lower rudder cap with the main wheels on the hangar floor. I bought it at a local hardware store. It has a longer shank than the popular drop-forged closed ring tie-down bolts. It has only been field tested one time when a friend and I both put a foot on the steps at the same time and started to climb up on the wing. This photo was taken the day we made the "test" of the eyebolt. Look carefully and you will see the eyebolt extends at least one inch below the skin of the fuselage.
You may get a better view of the tail tie down eyebolt via this photo.
When I was student pilot flying a Cessna 172 and learning how to land, I managed to over-rotate in the flare in ground effect and drag the tie-down bolt without any other part of the airplane touching the ground first.
Since then, nothing but wheels touch the ground when I fly.
Nose wheel tire
When I was at Oshkosh I asked Grove about a tire other than the one Van supplied and they told me that Desser is making a tire for the Sky Catcher and it is the same size. I talked to Desser Tire guy and sure enough they do. They are making it for Cessna. I ordered it and installed it last week. It fits great and works out just fine. I have a hard time making the turn off now at my field.
When I was at Oshkosh I asked Grove about a tire other than the one Van supplied and they told me that Desser is making a tire for the Sky Catcher and it is the same size. I talked to Desser Tire guy and sure enough they do. They are making it for Cessna. I ordered it and installed it last week. It fits great and works out just fine. I have a hard time making the turn off now at my field.
Grove Replacement Part #59-1ARV
Painless.... I called Grove Wheel Company, phone number (619) 562-1268, and in answer to your question, the kit comes with everything you need to put on your RV-6A, except you have to use your own bolt and nut for the axle. It is $299.00 for the kit, plus tax and shipping, and I ordered two extra felt seals, which were $2.00 each. Hope this helps you and anyone else that is interested.
I ordered the wheel today 10/7/08. Ed Poe
Painless.... I called Grove Wheel Company, phone number (619) 562-1268, and in answer to your question, the kit comes with everything you need to put on your RV-6A, except you have to use your own bolt and nut for the axle. It is $299.00 for the kit, plus tax and shipping, and I ordered two extra felt seals, which were $2.00 each. Hope this helps you and anyone else that is interested.
I ordered the wheel today 10/7/08. Ed Poe
One of the tests I made before my first flight was to be sure my tail tie down eyebolt hit the deck before the lower rudder cap with the main wheels on the hangar floor. I bought it at a local hardware store. It has a longer shank than the popular drop-forged closed ring tie-down bolts. It has only been field tested one time when a friend and I both put a foot on the steps at the same time and started to climb up on the wing. This photo was taken the day we made the "test" of the eyebolt. Look carefully and you will see the eyebolt extends at least one inch below the skin of the fuselage.
You may get a better view of the tail tie down eyebolt via this photo.
When I was student pilot flying a Cessna 172 and learning how to land, I managed to over-rotate in the flare in ground effect and drag the tie-down bolt without any other part of the airplane touching the ground first.
Since then, nothing but wheels touch the ground when I fly.
Looks great. I know I'll be having to do something to keep the tail from touching. I remember back when I was flight training. We were doing soft field touch and go's. The instructor said to be careful that when touching the nose will be high and if you were not careful you would hit on the tie down on power up. Well sure nuf I touched and hit the tie down, so I decided to have a little fun. I relaxed the yoke and pulled back all the way down the runway until he finally said, That's enough now, You know scrap, no scrap, scrap, no scrap.
logansc
Well Known Member
Just spent a considerable amount of time reading all the posts in this thread (including most/all of the posts referenced) and was a little surprised to finally read "According to Paul Merems, the old front gear was hardened according to spec despite my ability to bend it back with a pipe wrench." I wonder if there was any additional information there that could be shared: Correct steel (alloy, etc), properly hardened homogeneously from one end to the other, from the surface to the center, proper Rockwell numbers, etc?
If the nose gear strut was in fact fully up to spec, it seems like this leaves only over all nose strut design, excessive or improper nose wheel drag, a substantial runway transition lip, or pilot landing/rollout error as the possible causes---none of which really/fully seem supportable to me given the evidence and discussions in the posts to this point. What the heck caused this accident in a well maintained, well built, properly flown RV which was landed on a generally smooth, hard surface runway? I don't get it...
Regards,
Lee...
If the nose gear strut was in fact fully up to spec, it seems like this leaves only over all nose strut design, excessive or improper nose wheel drag, a substantial runway transition lip, or pilot landing/rollout error as the possible causes---none of which really/fully seem supportable to me given the evidence and discussions in the posts to this point. What the heck caused this accident in a well maintained, well built, properly flown RV which was landed on a generally smooth, hard surface runway? I don't get it...
Regards,
Lee...
I'm left with the same conclusion. I would generally say that you cannot bend back a piece of 1 inch round stock spring steel by hand even with a pipe wrench with a very long snipe.
I used to build sway bars for race cars and there is no way I could bend a piece of 1 inch stock cold clamped in my bench vice, with 6 feet hanging past with a 6 foot piece of tubing on that. You'd simply move the 500 pound bench. This was with either cold rolled mild steel or normalized 4140 alloy bar stock.
I used to build sway bars for race cars and there is no way I could bend a piece of 1 inch stock cold clamped in my bench vice, with 6 feet hanging past with a 6 foot piece of tubing on that. You'd simply move the 500 pound bench. This was with either cold rolled mild steel or normalized 4140 alloy bar stock.
