AD 81-02-02

81-02-02 GENERAL ELECTRIC COMPANY: Amendment 39-4004. Applies to all General Electric CT58 turboshaft engines incorporating stage one turbine wheel, part number 4002T17P02, with the following wheel serial numbers: 7753, 7761, 7762, 7767, 7768, 7783, 7799, 7803, 7811, 7815, 7817, 7819, 7820, 7823, 7824, 7828, 7839, 7845, and 7846.

Compliance required as indicated, unless already accomplished.

To prevent failure of stage one turbine wheels due to cracks originating from undersize rabbet groove radii, inspect forward and aft radii in accordance with the procedures contained in the accomplishment instruction section of General Electric Alert Service Bulletin CT58 (A72-159) CEB-255, dated July 9, 1979, or later FAA approved revision, or equivalent means approved by the Chief, Engineering and Manufacturing Branch, New England Region.

Inspect in accordance with the following schedule:

1. Turbine wheels with 3.950 hours or 7,900 cycles, or more, in service on the effective date of this AD, must be inspected within the next 50 hours or 100 cycles, whichever comes first.

2. Turbine wheels with less than 3,950 hours or 7,900 cycles in service, on the effective date of this AD, must be inspected prior to exceeding 4,000 hours or 8,000 cycles, whichever comes first.

Stage one turbine wheels with forward or aft rabbet groove radii of less than 0.010 inch must be removed and replaced with serviceable turbine wheels prior to further flight.

The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to General Electric Company, 1000 Western Avenue, Lynn, Massachusetts 01910. These documents may also be examined at Federal Aviation Administration, New England Region, 12 New England Executive Park, Burlington, Massachusetts 01803, and at FAA Headquarters, 800 Independence Avenue, S.W., Washington, D.C.

A historical file on this AD, which includes the incorporated material in full, is maintained by the FAA at its Headquarters in Washington, D.C., and at FAA, New England Region Headquarters, Burlington, Massachusetts.

This amendment becomes effective February 2, 1981.