AD 60-26-04

60-26-04 LOCKHEED: Amdt. 234 Part 507 Federal Register December 14, 1960. Applies to All 188 Aircraft.

Compliance required as indicated.

Failure of the clamp or flange of the swirl straightener assembly resulted in at least two cases of overheating the nacelle area causing extensive damage to the nacelle. In addition, there have been a number of failures of the retaining clamp and cracks in the flange area of this assembly caused by dynamic loads imposed by the sugar scoop deflection of exhaust gases.

The following modifications shall be accomplished to correct the above conditions at the first engine change after December 14, 1960.

(a) Remove the present sugar scoop and the lower bellmouth. Install a new lower bellmouth of extended length to mate properly with the engine after removal of the sugar scoop. When this rework has been accomplished, it will be necessary to relocate the fire sensing elements on the structural shroud.

(b) Tack-weld the vanes to the clips located on the perimeter of the straightener assembly.

(c) Add rubbing strips on the tailpipe shroud door and drill holes in the nacelle cooling duct assembly to cool the bellmouth.

(The above items must be accomplished in accordance with Lockheed S/B No. 430, which covers this same subject.)

This directive effective December 14, 1960.