AD 77-20-02

77-20-02 ENSTROM: Amendment 39-3046. Applies to Enstrom Models F28, F28A, F28C, 280 and 280C helicopters certificated in all categories with a 3.3 inch tail rotor blade with spindle P/N 28-15202. Within the next 50 hours time in service or six (6) months calendar time, whichever occurs first, accomplish the following unless already complied with:

1. Replace tail rotor spindle P/N 28-15202 with a new spindle P/N 28-15202-13 or a manufacturer-reworked spindle which may be identified by an eight (8) character serial number acid-etched on the outside of the spindle center section. Reference should be made to Enstrom Maintenance Manual Section 15 for disassembly and reassembly instructions. Special care should be taken to have the three bearing stack positioned with the closed side toward the hub and the retaining nut properly torqued to 35-40 foot-pounds and safetied.

2. Install strike tabs P/N 28-17308 extending forward on the blade leading edge under the outer balancingscrew.

This supersedes Amendment 39-2839 (42 FR 10841) AD 77-04-04.

This amendment is effective October 6, 1977, and was effective for all recipients of the airmail letter dated August 8, 1977, as amended by airmail letter dated August 22, 1977, upon receipt thereof.