78-09-09 DETROIT DIESEL ALLISON: Amendment 39-3207. Applies to 501-D13/501-D13A/501- D13D/501-D13E, and 501-D13H engines equipped with third stage turbine wheel P/N's 6788833, 6842143, 6841223, and 6846553 or fourth stage turbine wheel P/N's 6738424 and 6843014 installed in aircraft certificated in all categories.
Compliance required as follows unless previously accomplished:
To preclude possible engine failure resulting from third or fourth stage turbine wheel failure: Remove and classify all third and fourth stage turbine wheels with unknown carbide precipitation classifications in accordance with the compliance times specified in (a) and (b) below, and the procedures specified in Detroit Diesel Allison Commercial Overhaul Information Letter No. 349 Rev. 1 or later FAA approved revision. Wheels both newly and previously classified with carbide precipitation classifications of "Heavy" must be removed from service in accordance with the maximum life limits specified in (a) and (b) below. Wheels both newly and previously classified with carbide precipitation classifications of "Medium Heavy" must be removed from service in accordance with the maximum life limits specified in (c) through (h) below. Wheels of all other classifications may be returned to service and operated in accordance with the existing hourly life limits.
(a) For wheels of "Heavy" and unknown carbide precipitation classification which exceed 8000 total cycles upon the effective date of this AD, compliance is required within 300 cycles.
(b) For wheels of "Heavy" and unknown carbide precipitation classification which do not exceed 8000 total cycles upon the effective date of this AD, compliance is required prior to reaching 8300 total cycles.
(c) For wheels of "Medium Heavy" carbide precipitation classification which exceed 16,000 total cycles upon effective date of this AD, compliance is required within 200 cycles.
(d) For wheels of "Medium Heavy" carbide precipitation classification which have from 14,000 to 16,000 total cycles upon the effective date of this AD, compliance is required within the next 400 cycles or prior to exceeding 16,200 cycles whichever occurs first.
(e) For wheels of "Medium Heavy" carbide precipitation classification which have from 10,500 to 14,000 total cycles upon the effective date of this AD, compliance is required within the next 1000 cycles or prior to exceeding 14,400 total cycles whichever occurs first.
(f) For wheels of "Medium Heavy" carbide precipitation classification which have from 8000 to 10,500 total cycles on the effective date of this AD, compliance is required within the next 2000 cycles or prior to exceeding 11,500 total cycles whichever occurs first.
(g) For wheels of "Medium Heavy" carbide precipitation classification which have from 7000 to 8000 total cycles on the effective date of this AD, compliance is required prior to exceeding 10,000 cycles.
(h) For wheels of "Medium Heavy" carbide precipitation classification which do not exceed 7000 total cycles upon the effective date of this AD, compliance is required prior to exceeding 8000 cycles.
NOTE: For purposes of this airworthiness directive a cycle is defined as one takeoff.
The Detroit Diesel Allison Commercial Overhaul Information Letter identified in this directive is incorporated herein and made part hereof pursuant to 5 U.S.C. 552(a)(1). The Detroit Diesel Allison Commercial Overhaul Information Letter incorporated herein may be obtained upon request to Detroit Diesel Allison, Division of General Motors Corporation, P.O. Box 894, Indianapolis, Indiana 46206. This document may also be examined at the FAA Great Lakes Region, 2300 East Devon Avenue, Des Plaines, Illinois 60018 and at FAA Headquarters, 800 Independence Avenue, S.W., Washington, D.C. 20591. 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 the Great Lakes Region. (Detroit Diesel Allison Commercial Service Letter 501-D13 CSL-253 also pertains to this subject.)
This amendment becomes effective May 12, 1978.