Question on preforming tire change

[dingding]

I am new apprentice just graduated from tech school. I have question on working tire chage. How people determine the tire is safe to remove without deflate the tire first when they perform tire change on the field?

[MZUNGO]

this is why you must pay attention in tech school. the tire does not usually have to be deflated to remove the wheel assy from the axle on the gear leg. however if you try to disassemble the wheel with the tire still inflated you WILL get hurt or killed.
so as a usual practise i will deflate the tire while i am inspecting the axle and the new bearings and putting the new wheel on. i have a little deflator that screws on the valve stem, so it is usually done by the time i am packing up.
hth M

[dingding]

thanks for your reply. However, i am still wondering how you know the wheel half won't blow out to you when the time you removed the wheel assy off the axle. I believed there is a possibility the wheel half will blow out. Is there anything on the wheel assy which can be determined the wheel assy is safe to remove without deflate the tire first?

[log sheet]

You won't know until you remove it. I always deflate first as a safety precaution and have gotton Razzed for it ! There have been broken bolts found before! Check your MM ,I know in my manuals it's step one of removal.
Cheers!

[MZUNGO]

safety first, if in doubt deflate it fully and remove the valve core before removing the axle nut.

[cgzro]

I suppose one way to know the two wheel halves are in jeaprody of comming apart would be that the wheel would not turn as freely. It would be like you had the axle nut on too tight. Also as you undid the axle nut it would stay tight as the tire halves expanded a bit. I suppose you could watch the joint line as you undid the axle nut to look for any growing separation.

But as the other posters said, if in doubt just deflate before removing. Only takes a few seconds to deflate/re-inflate.

[Hedley]

Removing the valve works pretty well.

A couple years back, I saw a wheel blow, on
a crappy old 172 on the ramp. He pulled up
to the fuel bumps, and BANG - it lurched over
to one side. Weird.

That's with only 30 psi. I can only imagine
what would happen if a jet wheel blew.

[iflyforpie]

I'm two ways about it.

General aviation, remove wheel first, then deflate and disassemble. The pressures are so low and if the wheel is damaged it is pretty easy to see.

Anything King Airish and bigger, deflate tire first, then remove axle nut and wheel assembly. I remember the 727 had something like 200psi in the mains, not something I want to blow up while undoing the last threads on the nut.

[TwinOtterLover]

i agree with iflyforpie on that one, unless of course your going on a rescue because the tire is hissing or something like that, and inspect the bolts and the rim itself a bit before you take it off, i know you cant tell if a bolt is cracked but sometimes you might be able too. were i worked we had a rim with an inch and a half crack along the side near the bead seat and it was noticed just before we were about to take the axle nut off, that was a deflate before removal for sure

[scouty-dog]

Nitrogen is cheap. Your right hand (or whatever else is in the way) isn't so cheap. Deflate, then proceed.

Also, Always refer to your applicable aircraft maintenance manual. It's amazing what's in there.

[kilpicki]

2 types of assys, one a 2 part like in a King Air and could blow when the axel nut is loosed

the other like a RJ has a split rim and you can remove it with no problem of a explosion
there is no indication of a bad tire on removal

[Connaught]

i would expect that the axle nut wouldn't get 'finger lose' to spin off by hand,

remember my only experience is dash 8's and 737's so the smaller stuff i wouldn't know

Conn

[iflyforpie]

The remains of broken hub bolts or a bearing race slightly frozen to the axle might keep the axle nut lose and temporarily keep the wheel from coming apart. Then when you start to pull the wheel it might blow up in your face.

Take the nitrogen out, chances are it's coming out anyways when the tire goes to the shop.

[billy ray valintine]

always deflate the tire,read the manual.
if the axle nut has a high torque while loosening,that's a sign.
check the tie bolts,rims for cracks etc.
tires are nothing more than a bomb waiting to explode.
in the twenty five years i've been an ame,i have seen many very scary
situations involving tires.
a tire with 200 psi will go right through you if it lets go. be safe in this area.
where i work,i see guys all the time change tires without deflating first.
i guess it's just a matter of time before they learn the hard way!