What's with the freaking flat tires???

[Yooper Rocketman]

We landed last night at 8 PM after my Mooney logged 7 hours yesterday flying to Tennessee and back.  I was going to fly to Appleton WI for my annual USSF soccer referee recertification class and I had a flat left main tire; argh, $55 wasted because not enough time to drive.  I aired it up and couldn't hear a leak but there was no way I was taking a chance.

I pulled the wheel off and in an hour the pressure had dropped 4 pounds so pulled it apart.  I found a tiny hole in the outer SIDE of the tube and nothing on the inside of the tire.   This is the third flat in 3 years, all in different locations on my plane, and have never found an obvious reason for the flat other than a tiny hole in the tubes.  In the last two cases I reused the tire with no further issue ( new Michelin Airstop tubes).

Talking with Chad at Kubick Aviation on our field he says he's seen so many flats in the recent years he has spare tires and tubes in all his charter aircraft.  Just last month we had to send our Airlifeline Bonanza down to Burke Lakefront in Cleveland with a tube for our Seneca.  We were told by the ( hard to find) mechanic there was no place in a Cleveland to get a tube?????

Talking over this issue with Chad and some other A&P's the only idea anyone has come up with low tire pressures, although we never have the valve stems torn off?

On mine today it felt like I had "sand" between the tire and tube when I was pulling the tube out.  Found it appeared to be tiny rubber particulate but was as hard as sand.  Wondering if a low air pressure could cause abrasion between the tire and tube, especially on the side wall creating this grit.   I've washed everything up good and will reassemble with original tire.  

Anyone heard of issues lately with flats like this?

Tom

 

 

 

[Dream to fly]

I had several issues when I first got my plane and the tire was new along with the tube.  I finally went old school and put tire powder in the tire and made sure the new tube was coated too.  No issues since (knock on wood).  My thinking is if the tubes sit on shelves before being used the rubber does dry out some on the surface.  So a small grain of sand will wear a hole.  The powder keeps everything soft and lubricated. 

[RLCarter]

Tire talc the crap out it...Check your tube for folds and check if the hole is on one of those folds

[Yooper Rocketman]

I've always did all of that, talcum in tube and tire.  Just finished the job and checked the other tires.  Other main was at 30 PSI and spec for the Rocket is 45 PSI on the mains, 49 PSI on the nose.  Nose was at 37 PSI.  All tires were good in August and checked now in heated hangar, so not temperature related.  So much for "Air Stop Tubes".  I think it's tube to tire abrasion when the air pressure gets a little low.  

I wonder what the talc does after in there for a while, especially if used generously (which was my procedure before)?  We actually lightened up on it this time so no excess was left in the tire.  Concerned it might have been the source of the tiny grit found in the tire.  The whole in the tube was amazingly small so suspect from something abrating like hardened rubber debris or the talc  maybe balled into tiny grit particles because we know they were clean on original assembly. 

Tom

[ArtVandelay]

Interesting that the rocket specified pressure is 45, the J is 30.
I’ve always tried to keep mains 32-33, never liked the lower pressure, I might up it to 35.

[kortopates]

34 minutes ago, teejayevans said:

Interesting that the rocket specified pressure is 45, the J is 30.
I’ve always tried to keep mains 32-33, never liked the lower pressure, I might up it to 35.

All the K's are 42 psi on mains and 49 on nose (nose is same as J) . Even the Encore's increase to max weight of 3130 didn't change the tire pressure which is heavier than the Rocket's landing weight (3083 lbs - the rocket's take off weight is 3200 lbs - or 70lbs more than the Encore). But I see no mention of tire pressure changes in the Rocket POH supplement - perhaps @Yooper Rocketman miss recalls that or I missed it in the supplement?

[RLCarter]

5 hours ago, Yooper Rocketman said:

 

I wonder what the talc does after in there for a while, especially if used generously (which was my procedure before)?  We actually lightened up on it this time so no excess was left in the tire.  Concerned it might have been the source of the tiny grit found in the tire.  The whole in the tube was amazingly small so suspect from something abrating like hardened rubber debris or the talc  maybe balled into tiny grit particles because we know they were clean on original assembly. 

Tom

If it is abrasion it will look "sanded" around the hole in the tube, if the area around the hole looks normal, it's a puncture of some sort. Can't remember where I read it but there was an airport that used a wire bristle sweeper that was shedding bristles and giving everyone flats

[Yooper Rocketman]

7 hours ago, kortopates said:

All the K's are 42 psi on mains and 49 on nose (nose is same as J) . Even the Encore's increase to max weight of 3130 didn't change the tire pressure which is heavier than the Rocket's landing weight (3083 lbs - the rocket's take off weight is 3200 lbs - or 70lbs more than the Encore). But I see no mention of tire pressure changes in the Rocket POH supplement - perhaps @Yooper Rocketman miss recalls that or I missed it in the supplement?

Came straight from Darwin Conrad after a prop strike taxing on a ramp ( just barely in excess of a file field dressing) and dropping the nose a bit going over a drainage grate (2" at the most) trying to avoid a dump truck working construction on the airport.  Happened in the first year of ownership.  I got several tips from him during that phone call.

Taxi with yoke pulled full aft.   Keep air pressures as specs noted above.  Replace nose gear pucks every 5 years.  Avoid any dips during taxi that can get a forward tipping motion going.  That extra weight up front can be a challenge for the uninformed.

I was lucky enough to have several conversations with Darwin about a multitude of Rocket specific tips.  I bought my Rocket through  Irv Fehr, who sold a lot at Rockets for Darwin and was the most loyal Rocket owner out there.  Because of my obvious love of my Rocket, I was Irv's "reference" for a ton of prospective Rocket purchasers so he really liked me.   He hooked me up with Darwin who never declined a call from me.

Some day I'll share Darwin's story on the exhaust "heat muff" AD.  There's probably a lot of owners and shops complying with an AD that doesn't apply to their airplane due to a terribly written AD by the FAA.

Tom

[Yooper Rocketman]

4 hours ago, RLCarter said:

If it is abrasion it will look "sanded" around the hole in the tube, if the area around the hole looks normal, it's a puncture of some sort. Can't remember where I read it but there was an airport that used a wire bristle sweeper that was shedding bristles and giving everyone flats

Appreciate the feedback but can guarantee none of the three flats derived from a puncture.  I always mark the valve stem location so once tube leak is found I can inspect a specific area of the tire, inside and outside.  This time I even rolled the tire under pressure with great lighting and absolutely found no evidence of a puncture.  In addition, all three flats had leaks in sidewall, not a typical puncture area, especially on three consecutive ( but different location) flats.  Also, the tires were reused without removing any puncture item and have held air fine since.

Not sure why it's not possible for one grain of material to lodge at one spot between the tire and tube to create this hole?  I have no evidence of widespread abrasions.  I can't deny I'm stretching it with this theory but not finding too many reasonable conclusions to my and Chad's more recent experiences.  His have been on a wide variety of airplanes, wide variety of times in service, and wide variety of airports (not just our home airport).  The only common denominator we have found is the likelihood all the tires MAY have been down on air pressure from recommended spec.

Tom

[RLCarter]

@Yooper Rocketman a sidewall puncture is rare, 3 in a row...wow

[takair]

It’s been a few years since my last one, but I’ve had two, similar to what you describe.  In both cases, I took off with air and landed on a flat.  In both cases, the sidewall had a pinhole leak.  In both cases, the tube had a grainy appearance, like there was not enough rubber in the weave.  Filling out a service difficulty report might be a way to document these issues.  Seems to be related to poor tube quality, maybe compounded by low pressure.   Did you notice what the rest of the tube looked like, up close?

[MB65E]

Goodyear in the pst has had known issues with all of their tubes. They would get pinholes and cracks on the seams of the tube . They first started having problems as early as 04. The FAA maintains a list of service difficulty reports. Goodyear tubes have higher failure rates. They have corrected the issue but I'm sure many tubes are still out there.  I've been using Michelin Air stop tubes for this reason. 

-Matt

[Cyril Gibb]

Perhaps underinflation causes more sidewall flex to scuff the tube making granules?? Heated rubber hardening?

Each to his own, but I overinflate about 10% (30->33 and 49->54) and check at least once a month or sooner if the temperature drops significantly.  I know that I wear out the centre of the tread prematurely by maybe 5% or so.  However, 5% of a set of 3 tires once every 4-5 years is maybe $500 x 5% = $25.  That's waaaay less than even 1 unexpected flat repair, let alone the aggravation.

[Skybrd]

2 hours ago, MB65E said:

Goodyear in the pst has had known issues with all of their tubes. They would get pinholes and cracks on the seams of the tube . They first started having problems as early as 04. The FAA maintains a list of service difficulty reports. Goodyear tubes have higher failure rates. They have corrected the issue but I'm sure many tubes are still out there.  I've been using Michelin Air stop tubes for this reason. 

-Matt

 

2 hours ago, MB65E said:

Goodyear in the pst has had known issues with all of their tubes. They would get pinholes and cracks on the seams of the tube . They first started having problems as early as 04. The FAA maintains a list of service difficulty reports. Goodyear tubes have higher failure rates. They have corrected the issue but I'm sure many tubes are still out there.  I've been using Michelin Air stop tubes for this reason. 

-Matt

I had a new Goodyear tire and tube installed a while back and the tube failed on a seam. This was a pain since I was away from m home base, fortunately, I knew a mechanic that patched it so I could get back. Later the patch failed and I bought a Michelin tube. I think it was a factory defect, no more Goodyear tubes for me. 

[Hank]

Me three:  Goodyear Air Customs with Michelin Air Stop tubes on the mains, Condor tire and Michelin Air Stop tube on the nose (because it wears so much faster from turning). In the last 10 years, I've replaced the mains once, and just did the nose for the 3rd time yesterday. That little bitty, off-brand tire and tube cost more than a tire for my truck!

[takair]

1 hour ago, Hank said:

Me three:  Goodyear Air Customs with Michelin Air Stop tubes on the mains, Condor tire and Michelin Air Stop tube on the nose (because it wears so much faster from turning). In the last 10 years, I've replaced the mains once, and just did the nose for the 3rd time yesterday. That little bitty, off-brand tire and tube cost more than a tire for my truck!

It’s interesting, I feel like I go through two mains for every nose tire.  I wonder what others are seeing?  I tend to be heavy on the brakes, so perhaps that is part of it.  Will try the air stops on the next change.  Don’t recall what I have right now.

[Hank]

Brakes, brakes, brakes . . . Oh, those things I use so I don't move during the run up! Yeah, I use them as gently and infrequently as possible. 

Now that I don't have to back taxi and do a 180 for every home field departure and landing, I hope my nose tire will last longer. 

So far, no flats . . . .

[Yooper Rocketman]

3 hours ago, bluehighwayflyer said:

I put new stainless steel discs, pads, FCIIII tires, and Michelin Airstop tubes on my J 11.5 years and 550 hours ago when I bought it and they are all still installed and show minimal wear. In 25 years and 1200 hours I have never had a flat tire. Same installation practices as Tom. Go figure. I am truly stumped. 

 I don't think I had Michelin tubes installed on any of the flats.  They WERE replaced with them though.  

I think Cyril hit the nail on the head.  I need to get more consistent checking air pressure.  Flying 3 different planes tends to complicate the memory on considering that maintenance item during my preflight.  

Will probably add it to my checklists!

Tom

[EricJ]

1 hour ago, Yooper Rocketman said:

 I don't think I had Michelin tubes installed on any of the flats.  They WERE replaced with them though.  

I think Cyril hit the nail on the head.  I need to get more consistent checking air pressure.  Flying 3 different planes tends to complicate the memory on considering that maintenance item during my preflight.  

Will probably add it to my checklists!

Tom

This is especially true in the fall when the temperature drops and in the spring when it rises.   Tire pressures will change significantly with temperature.   e.g., if you set pressures at the end of the summer or early fall when it's warm, they'll be low after the temperature drops.    In the spring you may need to let air out to keep them from being too high.

 

[Yetti]

Street sweepers.   If you go to a runway with street sweepers they sometimes have a metal brush that throws out fine wire.

[xcrmckenna]

 I don't think I had Michelin tubes installed on any of the flats.  They WERE replaced with them though.  
I think Cyril hit the nail on the head.  I need to get more consistent checking air pressure.  Flying 3 different planes tends to complicate the memory on considering that maintenance item during my preflight.  
Will probably add it to my checklists!
Tom

Tom I will gladly check the air in all the tires if I can get a ride in the rocket or the Lancair when it gets out of the paint shop!!!!!!


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