Pinch Flat?

[Llewtrah381]

I ended up having a flat nosewheel tire this weekend, luckily discovered during preflight rather than on landing (I had flown several times already that day).

Looking at the tube, it has two good-sized holes in it, next to each other, but aligned perpendicular to the direction of the rim halves.


Is this consistent with a flat caused by the rim halves pinching it? I would have thought the holes would be aligned with the rims (about 90° from their orientation).

I replaced the tube 18 months ago, used talc, and was careful to avoid pinching the tube. I’m surprised both by how long this took to manifest itself and how the cuts are shaped if indeed it’s due to me pinching the tube on installation.

Thoughts?

 

[PaulS]

Hard to tell from that picture. Pinch flats in the typical sense would run parallel to the seam. Those look like they were caused by a pry bar or tire iron to me. But as I said, hard to tell.

 

[MauleSkinner]

Are they near the edge of the rim or the center of the wheel?

 

[Llewtrah381]

Are they near the edge of the rim or the center of the wheel?

Near the center of the wheel, which is consistent with a pinch from putting the wheel halves together but their orientation, the fact there are two of them, and being fine for 18 months are all confusing to me, although that may still be consistent.

There’s also a “bleb” that’s nearby but not leaking (arrow) and looks more like a manufacturing defect - although it’s more how I would think a pinch would be oriented.

If there was only one hole I’d kinda understand it being a pinch. But two holes and for so long past installation seems odd. It probably is a pinch - just wondering if I’m missing something else. This is an Aero Classic and I haven’t had good luck with them.

 

[Daleandee]

Could the tire pressure have been low and the tire slipped on the rim causing the tube to tear? Did you have a rim strip inside?

 

[Llewtrah381]

Could the tire pressure have been low and the tire slipped on the rim causing the tube to tear? Did you have a rim strip inside?

Having had a few flats in the past, I’m pretty consistent with checking tire pressures, especially on the nosewheel, which is smaller (5.00x5). The nose was 32 the day before (book is 30).

What’s a rim strip and do Piper Warriors have them?

 

[Daleandee]

Having had a few flats in the past, I’m pretty consistent with checking tire pressures, especially on the nosewheel, which is smaller (5.00x5). The nose was 32 the day before (book is 30).

What’s a rim strip and do Piper Warriors have them?

Don't know that Piper, or any other certified aircraft, have them. They are basically rubber strips that are used to protect the tube from the rim and mostly used on bicycles to keep spoke ends from touching the tube.

I've used them on ultralights and sport planes. I keep forgetting that while I'm flying experimental most on this forum are flying certified so you are not allowed to do things that make sense unless you have the blessing of a higher authority.

Here is an example of rim strips (tube liners) for autos ...

https://www.cokertire.com/accessories/tubes/tube-liners.html

 

[Bell206]

Is this consistent with a flat caused by the rim halves pinching it?

Not from what I see. Looks more like a manufacture defect or maybe an unintentional handling miscue. Definitely different.