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12 Nose Gear Leg Replacement Cracks

N621DF

I'm New Here
Of those RV12 owners who have replaced the WD-1201 nose gear leg with the new WD-1201-1, how many have discovered cracks in the older leg? As the SB 19-08-26 states, the RV12 that had a failure was used as a trainer and had more than 1700 hrs of 'abuse'. Would an RV12 under normal use also develop these cracks? I'm just wondering what other RV12 owners have found during the leg replacement.
 
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Quote from the SB:

The crack occurred at a location that is not visually inspectable. It is, therefore, strongly recommended that owners of RV-12/RV-12iS aircraft with the original style nose gear leg (WD-1201) replace that part with the available updated, reinforced leg - part number WD-1201-1.
 
Mine had 1050 hours all off grass farm strip when I changed it. Would not know about cracks because the SB states you cant see them. It worked good and looked OK when I changed it out.


Brad Stiefvater
Salem sd
 
Borescope inspection of nose gear leg

My A&P used a borescope to visually examine the interior of the nose gear leg from top to bottom but particularly at the bracket where the SB said the tracks occurred. Took photos also and did not observe any cracks. Not sure why this was not recommended as an interim solution since only one RV12 (used for training) experienced the crack.
 
I have 8 1/2 years and 989 hrs on my 12. Last annual I did a bore scope, but could not get a really good image that I would trust. I hint you would have to cut open the leg, polish the surface and PT it to be sure there is no crack. What Vans seems to be saying is that it’s a high duty location and they ant to prevent crack initiation.

In general what puzzles me is that this issue as well as the trim linkage and now the exhaust pipe SB seem to be identified in customer aircraft as opposed to Vans original airframe which now has over 2000 hours on it if I remember past posts.
 
In general what puzzles me is that this issue as well as the trim linkage and now the exhaust pipe SB seem to be identified in customer aircraft as opposed to Vans original airframe which now has over 2000 hours on it if I remember past posts.

Just some thoughts on three concerns you list:

Nose gear that failed was probably abused on an airplane used in training environment. Van’s used FEA Finite Element Analysis (not available back in the day) to identify potential design flaw. Better to change out strut than to suffer nose gear collapse and have a bad day.

Van’s RV-12 demonstrator may still have original design exhaust system with the mandrel-bent exhaust stacks not affected by the SB. Design was changed to allow more clearance muffler/oil cooler which necessitated stacks fabricated as weldments instead of one-piece construction which caused all the hoopla. My early SN 12, with close-clearance muffler/oil cooler, operates fine on hot summer days. I use full-synthetic oil which tolerates higher operating temps.

I will probably get black eye for this…. I think original stabilator trim servo is solid design and good application, and in my opinion, requires no remedial action. Ray Allen has been using this design successfully for many years. Here’s where I get black eye – there was some talk in an earlier thread that perhaps a few of the trim servos were dropped during assembly or abused by paint shop - perhaps even someone pushing on anti-servo trim tab. If Van’s allows 1000TT before replacement, the design/application can’t be too far off the mark.
 
RV12 Oil

Jim -

What 'full synthetic oil' do you use? Is it approved by ROTAX?

I've been using AeroShell Oil Sport Plus 4; is your full synthetic oil better?
 
Jim -

What 'full synthetic oil' do you use? Is it approved by ROTAX?

I've been using AeroShell Oil Sport Plus 4; is your full synthetic oil better?

I use Mobil 1 Racing 4T Full Synthetic Motorcycle Oil 10W-40. At one time it was listed as Rotax acceptable. Rotax then partnered with AeroShell and spread some fake news that oil formulations can be changed without notification to consumers - that's basically how AeroShell tied up the market...
 
ANSYS is an FEA model that has been around since the 70’s, but I don’t know what Vans used in the original design of the nose gear leg.

Maybe I read the SB wrong, but I thought it included the original mandrel bent exhaust too.
 
ANSYS is an FEA model that has been around since the 70’s, but I don’t know what Vans used in the original design of the nose gear leg.

Maybe I read the SB wrong, but I thought it included the original mandrel bent exhaust too.

SB 00005 does NOT include the original mandrel bent exhaust on cylinders 1 and 2. Just inspected mine on my 2012 completed RV-12 with mandrel bends. Does not apply. See the pictures included. https://www.vansaircraft.com/service-information-and-revisions/?aircraft=rv-12&doctype=all
 
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