April 2010 article


Thinking out loud the other day, I asked my wife,” Wonder what I ought to write about for my next “Safety Note?”  She   spontaneously came back with; “Tires!”  That must have had an effect on my psyche because the word kept recurring in my mind until here it is “Tires” (which could lead to “Tears” if you don’t pay attention to them).

Tires are probably one of the most neglected parts of the aircraft when it comes to preflight and maintenance.  Let’s take air pressure.  When was the last time (excluding the annual) that you took an air pressure gauge and checked the air pressure in your aircraft’s tires?  Your owner’s manual should have a quick reference chart for proper inflation pertaining to outside air temperature (OAT) possibly in conjunction with gross weight of your aircraft.  Logic should tell you that cold OAT will significantly reduce the air pressure in your tires and just the opposite effect can occur with hot OAT.  Both conditions can lead to hazardous ground handling of your aircraft, ie.,  swerving to one side while taking off or landing (combine that with a little crosswind and you could have your hands full), blowing a tire if you hit a pothole, uneven pavement seam, or foreign object, like a deer antler (attempted humor).  Under inflation will increase your takeoff roll and cause overheating.  Over inflation will cause middle tire wear and reduce the shock absorbing quality of your tires.  Both under and over inflation can lead to tire damage and blowouts.

I know a pilot who ran very low air pressure in his ultra-light tires to enhance their shock absorbing qualities.  It worked….until they slipped on the rims and cut his valve stems, resulting in very poor shock absorbing qualities.

Do you want to impress the person sitting next to you on your next airline trip?  Tell him that you are sure glad that you are on a United States airliner instead of a Mexican airliner. He will of course ask “Why?”  and you can tell him because United States airlines require pure nitrogen in their tires but Mexican airlines use just plain air.  Hopefully, he will get that “So?” look on his face and then you can explain to him the chemistry requirements of fire needing oxygen to burn and if all that is available is nitrogen then the hazard of a fire is reduced if a brake becomes overheated or catches on fire.  You may have a friend for life.  Then again, he may quit speaking to you.  If he looks the least bit impressed and you happen to be on a 747 you can explain that you are rolling on 18 tires, each having 16 plies of the highest quality rubber and are inflated to 215 psi at an OAT of 70`F! (Don’t tell him they were under contract to the lowest bidder.)

I had owned my latest trike for a couple months and imagine my aggravation upon arrival at my hanger one day to discover a right main flat tire.  I removed it and took it to TMA in here in Rapid City.  The fixit man looked me straight in the eye and said the hole in the tube was caused by a parts sticker!  Yep, you got it, Toyota….a parts sticker about the size of a postage stamp was not removed before assembling the tire and it had rubbed a hole in the tube.  Yes, I had it properly inflated, and yes I wrote a quick notification to the manufacturer.

Don't let the little things in life get to you, do a thorough preflight and don't forget to check your tires, all aspects!

Fly Safe!


Darrel W Sauder,  EAA Chapter 39, Rapid City, SD

return to Safety First

Copyright © Specialty Cars Unlimited Sioux Falls, SD