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  #1  
Old 09-03-2018, 05:20 PM
pilotyoung pilotyoung is offline
 
Join Date: Jan 2018
Location: Birmingham, AL
Posts: 44
Default Tire Problem

I am posting this situation to keep someone else from making the same mistake I did. I am a new owner, I bought my RV-12 in February 2018. I have been a pilot for many years, but am new to maintenance.

Saturday I flew from KEET to KBGF to attend a fly-in breakfast. I took a friend with me so we could enjoy the fly-in together.

When I landed at KBGF I could not steer the aircraft. It started going left and nothing I could do would stop it. I was able to miss a taxi light by using the left brake. The aircraft ran off the runway into the grass and did a 180 before it stopped. So we were sitting in the aircraft, facing the way we flew in, and not knowing for sure what happened. I thought the left tire had blown.

We got out of the aircraft and the left tire was flat. The aircraft has slid on the wheel pants on the runway before it exited to the left. The airport manager and a couple other people came out to see if we were OK and we were. They help me jack the aircraft up, get the wheel pant off, and then we were able to pull it onto the runway, put a dolly under the left wheel, and tow it to the ramp. We then had breakfast and after eating I went to work taking the left wheel off. When I got it off, I was surprised that there was not a bad spot on the tire and it appeared normal. I put air into it to see what would happen. It was holding air except it was leaking through the valve stem. After tightening the valve stem, it held air. I reinstalled the wheel, and flew back to KEET. I went to the airport today and the tire was still holding air.

I was thinking about what happened to cause this. Several months ago I purchased a tool that came with new valve caps so I could check the tire pressure and add air with the wheel pants on. There is a hole in each wheel pant, and by inserting the tool into the hole (after aligning the value stem with the hole) you can take the valve cap off. I also bought an air chuck with a straight stem so I can add air through the hole. The tool is then used to put the cap back on.

Shortly after getting those new caps and installing them, I went to the hangar one day and the left tire was flat. I went through the procedure and added air. For several months the air pressure has remained good.

Last Thursday I decided to check the pressure in the tires and I added a couple of pounds of air to both main tires. Saturday morning I looked at all the tires and they all appeared to be normal.

After winding up in the grass and taking the wheel pant off, I realized the cap on the left valve stem was on crooked and therefore it was not tight. I realized that it had cross threaded when using the tool blind through the hole. The cap has a rubber seal in it so that when it is tight, it will seal the valve stem.

So after thinking about this entire situation, I realized that for the last several months the cap has been sealing the tire and keeping the air from escaping. When I didn't get it on tight, and flew up to 5,500 feet for the trip, the outside air pressure was lower and allowed all the air to escape and therefore I landed on a flat tire. I was fortunate that the only damage was to the wheel pant.

The moral to this story, and the reason I am sharing it, is that if you think there is a problem (tire losing pressure), there probably is. I had wondered for a few months why that tire was flat that day, and why it held air pressure for several months after I filled it. I now know, the valve stem was leaking and I did not check it. I should have investigated further and found the problem initially and before flying the aircraft.

I now have all the wheel pants off, and will have them off until I repair the left wheel pant. I like them off so I can see the whole tire and add air easily. I am wondering how much speed you really gain by having the wheel pants on.

I am going to Triple Tree this week so I will see what my cruise speed is without the wheel pants.

The people at KBGF were wonderful. The airport manager, a couple of mechanics, etc. helped get the aircraft to the ramp and then loaned me tools so I could get the aircraft flying. A friend who is an RV-12 owner and lives fairly close flew over and brought me a tire and tube, which I ended up not needing. But the friendless and helpfulness of aircraft owners, mechanics, etc, was wonderful.

I look forward to going back to the breakfast there again, and arriving in a less eventful way and getting to enjoy the breakfast and the company.

Thanks again to those people who helped me. I hope by sharing this story, my mistake, that someone will be able to avoid a similar situation.
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  #2  
Old 09-03-2018, 06:21 PM
Piper J3's Avatar
Piper J3 Piper J3 is online now
 
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Location: Hinckley, Ohio
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I would say, at the very least, you need to replace the tube if the tire has been run flat, and depending on age, you may want to replace all three tubes. AIRSTOP tubes work very well to minimize air leakage over time. With AIRSTOP tubes I need to check air pressure only twice a year, and even at that, there is very little loss of pressure.

You have found out that differential braking is absolutely necessary for directional control on the ground. I would inspect brake linings and also make sure aluminum hydraulic brake lines on each gear leg are in good condition. I replaced my aluminum gear leg lines with braided Teflon lines from Aircraft Specialty. Might also want to check for air bubbles in crossover tubing in the cabin and bleed the brakes if necessary.
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Jim Stricker
Hinckley, Ohio
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 406

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #3  
Old 09-03-2018, 06:29 PM
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tomkk tomkk is offline
 
Join Date: Apr 2014
Location: Port Orange, Fl
Posts: 795
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Quote:
Originally Posted by pilotyoung View Post
... I am wondering how much speed you really gain by having the wheel pants on. ...
Good info, glad it ended up turning out OK. I guess I'll add a couple of additional cautions.

My valve caps have a small circular partition that's concentric with the outer wall of the cap. I guess it's purpose must be to surround valve core and somehow protect it from I don't know what. In any case, I once had a slightly bent valve core stem in the nose wheel Schrader valve. It was bent enough so it contacted that inner wall which depressed the valve somewhat and let the air out of the tire. I'm more careful now when I put the dust caps on the valve stem.

Which brings up my second caution. That incident I mentioned above happened on my nose wheel. I would have thought that a tire with little or no air would look flat but mine didn't. As a matter of fact, at least with my nose wheel, I had no idea it was flat! I had a friend standing by to see me off and he stopped me as soon as I boarded the aircraft. The tire looked perfectly normal in the preflight and it wasn't until I added my extra weight (about 210#) that it was apparent that it was flat. Even knowing it was flat, we both looked at it with me out of the aircraft and it looked normal. The sidewalls must just be stiff enough, coupled with what was probably a small amount of air, to support the plane without flattening the tire. Anyway, part of my preflight now is to "bounce" the aircraft a bit and watch the tires - low pressure is pretty obvious when I make those movements.

fwiw, I always fly without the wheel fairings locally so I can see the tires, brakes and brake lines. I do add the fairings for trips. It takes me about 45 mins to add them and I gain about 5 kts or so.
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Port Orange, Fl
RV-12 N121TK ELSA #120845; first flight 06/10/2015
RV-12 N918EN ELSA #120995 Eagles Nest Project
SPA Panther N26TK in progress
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  #4  
Old 09-03-2018, 06:30 PM
Mel's Avatar
Mel Mel is online now
 
Join Date: Mar 2005
Location: Dallas area
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Any time you add air to a tire, any kind of tire, you should wipe a bit of spit onto the valve stem. If a bubble appears, the valve stem is leaking for some reason. Never depend on the cap to hold air. The cap is simply a device to protect the valve core.
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North Texas (8TA5)
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  #5  
Old 09-03-2018, 09:18 PM
Tommy123 Tommy123 is offline
 
Join Date: Jul 2018
Location: Naples fl
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Default Cap

The cap is not there to hold tire pressure! It is only to protect the valve!
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  #6  
Old 09-03-2018, 09:55 PM
RFSchaller RFSchaller is offline
 
Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 2,342
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I had a bad valve poppet on one of my valve stems. I bought a kit at Harbor Freight that had a tool to remove the poppet and some extra poppets. A simple fix that took Ten minutes and lasted 500 hours until tire and tube change out.

I hate that a flat puts the wheel pant n the ground. I ended up removing my wheel pants to simplify maintaining tire pressure. Once more proving life is more fun with your pants off!😜
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  #7  
Old 09-03-2018, 11:44 PM
pilotyoung pilotyoung is offline
 
Join Date: Jan 2018
Location: Birmingham, AL
Posts: 44
Default Tire Problem

My RV-12 has Aero Classic Tires. I was looking at Condor tires in Aircraft Spruce catalog.

Is anyone using Condor tires? Is there a major difference between the two?

Thanks.
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  #8  
Old 09-04-2018, 03:59 AM
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Piper J3 Piper J3 is online now
 
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I installed Desser 500-5 6 PLY AWBS RETREAD, ELITE PREMIUM 2 GROOVE (ELITE) and have over 250 hours on them. Excellent wear. Cost was $140 for two tires with free 500-5 AERO CLASSIC **BUTYL** INNER TUBE TR-67 (GL-5067) back in March 2016. Haven’t even flipped them yet to even wear pattern. Tire is slightly larger so need to enlarge wheel pant opening to maintain 1/2” clearance all around.
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Jim Stricker
Hinckley, Ohio
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 406

LSRM-A Certificate 2016
Special Thanks to EJ Trucks

Last edited by Piper J3 : 09-04-2018 at 10:40 AM.
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  #9  
Old 09-04-2018, 06:55 AM
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tomkk tomkk is offline
 
Join Date: Apr 2014
Location: Port Orange, Fl
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Quote:
Originally Posted by Piper J3 View Post
I installed Dresser 500-5 6 PLY AWBS RETREAD, ELITE PREMIUM 2 GROOVE (ELITE) and have over 250 hours on them. Excellent wear.
I have the same ones. I have more than twice as many landings and counting on my Desser Elites than I got on the original Aero Classics ...
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Tom
Port Orange, Fl
RV-12 N121TK ELSA #120845; first flight 06/10/2015
RV-12 N918EN ELSA #120995 Eagles Nest Project
SPA Panther N26TK in progress
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  #10  
Old 09-04-2018, 08:56 AM
pilotyoung pilotyoung is offline
 
Join Date: Jan 2018
Location: Birmingham, AL
Posts: 44
Default Tire Problem

Where did you guys buy your Dresser tires?
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