Inspection Detail

Inspection: 15193428 - Key Airlines

Inspection Information - Office: Utah Division Of Occupational Safety And Health

Investigation Summary

EMPLOYEE #1 WAS INFLATING AN UNDERINFLATED NOSE GEAR TIRE ON A LOCKHEED JETSTAR, USING COMPRESSED NITROGEN GAS. HE HEARD A HISSING NOISE. SHORTLY THEREAFTER, THE WHEEL EXPLODED, SENDING WHEEL FRAGMENTS FLYING INTO EMPLOYEE #1 WHO WAS STANDING DIRECTLY IN FRONT OF THE WHEEL. IT APPEARS THAT THE O RING INSIDE THE TWO PIECE ALUMINUM ALLOY WHEEL WAS DEFECTIVE, ALLOWING NITROGEN TO LEAK INTO THE WHEEL. PRESSURE BUILT UP INSIDE THE WHEEL, CAUSING IT TO EXPLODE. THE WEIGHT OF THE AIRCRAFT WAS ON THE TIRES AT THE TIME OF THE MISHAP. THE WHEEL IS COMPOSED OF TWO PARTS HELD TOGETHER BY EIGHT TNRV BOLTS. THE TORQUE ON THE BOLTS WAS CHECKED ON THE UNDAMAGED NOSE GEAR WHEEL (DUAL). THREE BOLTS WERE 30-50 INCH LBS OVER TORQUED, SIX WERE 30-70 INCH LBS UNDER TORQUED. THE PROPER TORQUE IS 100-120 INCH LBS. THE WHEEL WAS A B.F. GOODRICH TYPE VII, SERIES #693, MANUFACTURED JANUARY 1967. THE STATIC LOAD WAS 3,300 POUNDS. THE TIRE PRESSURE WAS 220 POUNDS. IT ALSO APPEARED FROM A FRAGMENT THAT THERE MAY HAVE BEEN A HAIRLINE CRACK IN THE WHEEL PRIOR TO THE MISHAP.

Keywords: WHEEL, EXPLOSION, INFLATING, MULTIPIECE RIM WHEEL