83-01-04 DETROIT DIESEL ALLISON: Amendment 39-4539. Applies to Detroit Diesel Allison (DDA) Model 250-C28B and -C28C series engines with turbine assembly serial numbers CAT 70001 thru 70186, 70188, and 70191.
Compliance required, as indicated, unless already accomplished. To prevent possible damage to the first stage turbine wheel due to oil fires caused by the improper U-ring gasket or the proper U-ring gasket incorrectly installed at the No. 8 bearing retainer plate, accomplish the following:
a. Within the next 5 hours time in service after the effective date of this AD, inspect and pressure test the No. 8 bearing sump area, in accordance with Detroit Diesel Allison Commercial Engine Alert Bulletin CEB- A-72-2082, dated January 3, 1983, or later FAA approved revisions, on affected turbine assemblies that meet either of the following conditions:
1. Turbine Assemblies with less than 500 hours time since new.
2. Turbine Assemblies that are experiencing or have experienced oil consumption in excess of one quart (0.9 liter) per hour.
NOTE: Turbine Assemblies that have been overhauled and have had the pressure check accomplished or have been operated for more than 500 hours time since new, and have less than one quart (0.9 liter) per hour oil consumption are not required to have the inspection and pressure test.
b. Inspect and pressure test, before initial flight, uninstalled affected turbine assembly No. 8 bearing sump area per Detroit Diesel Allison Commercial Engine Alert Bulletin CEB-A-2082, dated January 3, 1983, or later FAA approved revisions.
Special flight permits may be issued in accordance with FARs 21.197 and 21.199 to operate aircraft to a base where compliance with this AD can be accomplished.
Upon request of the operator, an equivalent means of compliance with the requirements of this AD may be approved by the Manager, Chicago Aircraft Certification Office, Federal Aviation Administration, 2300 East Devon Avenue, Des Plaines,Illinois 60018.
This amendment becomes effective January 24, 1983.