79-24-07 DETROIT DIESEL ALLISON: Amendment 39-3624. Applies to Aeroproducts Models A6441FN-606 and -606A propeller blades. Compliance is required as indicated.
To preclude propeller blade failure due to fatigue, complete an interim inspection of the blades in accordance with Detroit Diesel Allison Commercial Service Letter 501-D13/-606 CSL-240 dated March 1, 1976 thru Revision 3 dated July 26, 1977 as follows:
NOTE: The fluorescent magnetic particle method must be used.
a. If blades have more than 4000 hours since the last interim inspection or overhaul, complete an inspection within the next 150 hours time in service.
b. If blades have 3150 to 4000 hours since the last interim inspection or overhaul, complete an inspection within the next 450 hours, or prior to exceeding 4150 hours, whichever occurs first.
c. If blades have 2550 to 3149 hours since the last interim inspection or overhaul, complete an inspection within 600 hours, or prior to exceeding 3600 hours, whichever occurs first.
d. If blades have less than 2550 hours since the last interim inspection or overhaul, complete an inspection prior to exceeding 3150 hours.
e. If blade cracks are found during these inspections and/or if spalled areas are found exceeding limits as per CSL-240, entire propeller hub must also be inspected per CSL-240.
f. Report the results of all inspections to Chief, Engineering and Manufacturing Branch, AGL-210, FAA, 2300 East Devon Avenue, Des Plaines, Illinois 60018. (Reporting approved by Office of Management and Budget under OMB No. 04-RO-174.)
g. All subsequent interim inspections shall be carried out at intervals not to exceed 3150 hours time in service.
h. Alternate inspections or other actions which provide equivalent levels of safety may be used when approved by the Chief, Engineering and Manufacturing Branch, FAA, Great Lakes Region.
This amendment becomes effective December 5, 1979.