Airworthiness Directives (ADs) Issued

Engine

  • AD 89-20-01, CF6-6 series, final rule request for comments, issued September 15, 1989. Requires ultrasonic inspections of stage 1 fan disks for metallurgical defects that could adversely affect the service life of the disk.
  • AD 89-20-01 R1, CF6-6 series, final rule request for comments, issued November 24, 1989. Amends AD 89-20-01 by adding 50 additional stage 1 fan disk serial numbers to the tables in the AD, requiring removal and ultrasonic inspections (USI) for metallurgical defects. The FAA determined that this additional population of stage 1 fan disks was manufactured using the same process as the disk that failed on UAL 232.
  • AD 91-12-09, CF6 series, final rule request for comments, issued May 21, 1991. Further analysis indicates that metallurgical defects located in certain locations on the stage 1 fan disk may not be detectable by USI. This AD requires a new inspection procedure using eddy current inspections.
  • AD 91-15-03, CF6 series, final rule request for comments, issued June 25, 1991. Adds additional stage 1 fan disks to the inspection program.

NOTE: The inspections required by the engine ADs identified a second CF6 fan disk that had a metallurgical defect located in a low-stress region of the part. This disk was subsequently removed from service.

Aircraft

  • AD 90-13-07, DC-10 series, final rule following NPRM, issued June 4, 1990. Requires modification of aircraft hydraulic systems to prevent total loss of hydraulic power and flight control systems.
  • AD 91-23-14, DC-10 series, effective January 9, 1992. Requires the hydraulic shut-off valve be wired to the master caution warning system.
  • AD 95-14-06, DC-10 series, effective August 18, 1995. Requires various modifications to the flight controls, hydraulic systems, and landing gear to enhance the controllability of these aircraft in the event of catastrophic damage to all aircraft hydraulic systems. These changes were prompted by recommendations from the Systems Review Task Force.

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