Accident Lockheed L-1011 TriStar 1 N723DA, Thursday 26 June 1997

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Date:	Thursday 26 June 1997
Time:	23:50 LT
Type:	Lockheed L-1011 TriStar 1
Owner/operator:	Delta Air Lines
Registration:	N723DA
MSN:	193C-1150
Total airframe hrs:	60686 hours
Engine model:	Rolls-Royce RB211-22B
Fatalities:	Fatalities: 0 / Occupants: 96
Other fatalities:	0
Aircraft damage:	None
Category:	Accident
Location:	Cincinnati/Northern Kentucky Airport, KY (CVG/KCVG) - United States of America
Phase:	Pushback / towing
Nature:	Unknown
Departure airport:	Cincinnati/Northern Kentucky Airport, KY (CVG/KCVG)
Destination airport:	Atlanta, GA (KATL)
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
The flight attendant was in the elevator when it dropped to the galley level, and she received a fractured ankle. The elevator was operated by a drive shaft with two co-located shafts. The inner shaft was located inside the secondary shaft. Examination of the elevator lift mechanism revealed that the primary shaft had failed in rotating-bending fatigue. The secondary shaft failure originated from a fatigue crack in a sharp corner of the teeth. Corrosion was found on the surface of the crack. The shafts were inspected at 300-hour intervals, and had last been inspected 33 hours prior to the accident.

Probable Cause: the failure of the primary and secondary elevator driveshafts, and the failure of maintenance personnel to detect the failure of the primary shaft during scheduled inspections.

Accident investigation: