REFLECTOR:Gear Up

John Dibble reflector@tvbf.org
Sat, 03 Apr 2004 09:30:16 -0600


Scott B,
Why is the fork made of cast aluminum?  Cast metal doesn't bend, but cracks under
stress.  Wouldn't a steel fork that bends under (excessive) stress be better?
Good comments on the main gear heat issue.  Rather than upgrade my matcos (stronger
brakes = more heat), I think I'll upgrade my TOL skills.
John

Scott Baker wrote:

> Fred,
>     I don't think it's quite fair for anyone to criticize the factory for a
> busted nose wheel fork if it is of the old (smaller) design.  The factory
> has mentioned this time after time after time in the VV that the old forks
> should be replaced.  The factory subsidized the cost of the new forks.  If
> someone is operating an old fork today - they are ignoring the warning from
> the factory.  So please don't lay blame on the factory for an "almost
> mishap" when your older fork developed a crack.
>     In regards to the main wheel getting stuck on the lip at the bottom of
> the wheel well.  This was caused as you know when the main gear leg warped
> when it became overheated after being exposed to the excessively hot heat
> from the brakes.  Overheated brakes and the problems that come from
> overheated brakes has also been the subject of repeated articles in the
> Velocity Views.  If you ride the brakes or do repeated hard braking, a lot
> of heat develops around the brake disk, which is then transferred to the
> gear leg.  Too much heat leads to a softening of the gear legs.  And if
> there is any stress on the gear legs when they are soft, the legs will warp
> to relieve the stress.  We need to a) understand that this situation is
> possible, b) try to avoid overheating the brakes, and c) when the brakes are
> overheated, do something about it like throwing a wet towel around the leg
> and/or pulling the aircraft forward about 15' after it has been stopped so
> that the pressures on the gear leg are neutralized, and lastly d) look for a
> warped leg during the preflight, just in case a,b,and c have been ignored.
> If the wheel or lower portion of the gear leg looks crooked, the geometry of
> the gear has obviously changed - and therefore the clearances of the gear
> going into the wheel well will be changed and there is a possibility of
> getting wheel stuck in the well.  The lip at the wheel well presents a ledge
> where hardware can catch and hang-up when this happens - so yes, I agree
> with you that not having a lip is better than having a lip - but eliminating
> the lip does not eliminate the possibility of a stuck gear ... the tire
> could easily wedge itself against the wheel well and the gear could be stuck
> to the point that it might not come down.  Again the root of this paragraph
> was overheated brakes and warped gear legs.