Categories: all aviation Building a Biplane bicycle gadgets misc motorcycle theater
I recently had the opportunity to level-up my airplane game: changing a tire.
I've changed many a tire on motorcycle, bicycle, and once or twice on a car, but changing a tire on an airplane was a new experience. I can see why the FAA allows pilots to do it: it's surprisingly easy.
On a motorcycle with a tubeless tire (which has been a lot of my experience), you have to employ a distressing amount of force to unseat the bead, and getting the tire fully on the rim can be a surprising amount of work as well. Seating the bead is an exercise in "Will it explode and kill me?" as you apply 80 PSI to a tire rated for 40, and it slides into place with two loud BANG! noises.
An airplane, on the other hand, is a gentle, simple affair. You jack up the landing gear leg (simple on the Champ I was working on, my 1956 Champion 7EC), undo the axle nut, and pull the wheel off (carefully placing the bearings to the side, to be cleaned, inspected, and repacked with grease). The tire is deflated first, just in case the axle nut was the only thing holding it together. Then you undo the three bolts holding the wheel halves together, and pull them out of the tire. No force required, it just all gently comes apart.
In my case, I was missing some key components, so the process took much longer than it should have. I didn't have replacement cotter pins (special aviation cotter pins are required, though at 17 cents apiece, they don't exactly break the bank), so I had to walk over to the maintenance hangar and spend $1.80 on 10. After I took the wheel halves apart, looking over the bolts that hold the halves together, I wasn't entirely convinced they were aviation-grade hardware, so another walk to the maintenance hangar, and $20 later, I had a complete set of replacement hardware for both wheels.
As it came time to re-assemble the wheel with the new tire in place, it became obvious that I was missing a torque wrench, so I toddled off to Harbor Freight to blow $22 on a small clicker wrench in inch-pounds -- the one I have at home can't be set to a small enough value to deal with aviation hardware, so I hadn't bothered to bring it. I switched on the air compressor that came with the plane, and.... nothing happened. Poked around a little bit, but it wasn't obvious what was wrong, so I drove up the road to a bike shop and bought the fatty-est floor pump they had, and now I've got an air source that doesn't make any noise or need any power.
Fortunately, I had the appropriate grease (AeroShell #5) on hand, and greased up the bearings as I reassembled the whole mess in the afternoon sun, wishing the rain clouds would come back so I'd stop overheating. The axle nut is a weird one, just a round section of pipe, appropriately threaded and with holes spaced every 30° around its circumference: it should be basically finger tight, then you throw a cotter pin through it to keep it from coming loose.
Unfortunately, I discovered that the axle nut cover has two of three screw-holes stripped out, so I'll be taking it to someone for some Helicoil action. I'd hate to see my lightweight hubcap spinning away from me on landing some day.
In all, though, the experience of changing an airplane tire was gentle and lightweight compared to dealing with motorcycle or even bicycle tires. It was delightful in how easy it was. I can't wait to tackle the next one, particularly now that I've got all the bits and pieces read to go.
Posted at 20:51 permanent link category: /aviation
Categories: all aviation Building a Biplane bicycle gadgets misc motorcycle theater