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?