Why did inspections fail to detect excessive wear?
On January 31st 2000, an Alaska Air MD-80 disappeared into the Pacific ocean off the coast of Santa Barbara, California with 88 souls aboard. The crash investigation determined the cause to be…
a loss of airplane pitch control resulting from the in-flight failure of the horizontal stabilizer trim system jackscrew assembly’s Trapezoidal nut threads. The thread failure was caused by excessive wear resulting from … insufficient lubrication of the jackscrew assembly.
Why did inspections fail to detect the excessive wear?