Primary finding
Probable cause
Inadequate lubrication which caused stress corrosion cracking and the separation of the right wing number two flap vane.
Investigator assessment
Analysis narrative
The pilot was landing on runway 4r, when according to the pilot, he was established on the glide slope when he felt a vibration. He reported that the flying characteristics degraded and he made the necessary correction successfully. There were no indications in the cockpit of any failure. The airplane touched down 2 minutes later and taxied to the gate without any further incidence. Inspection of the airplane revealed separation of the no. 2 flap vane from the right wing. Further testing by the NTSB lab revealed the separation occurred due to stress corrosion and fatigue cracking that initiated at the lug bore.
Source record
Factual narrative
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