AD 68-07-05

68-07-05 MCDONNELL DOUGLAS: Amendment 39-577. Applies to all DC-3 Series and C-47 Series Airplanes having an Elevator P/N 5115210 incorporating Elevator Ribs P/N 5115210-5 or -9 and Trim Tab Hinge P/N 1141847 (hereinafter referred to as the Elevator Installation).

There have been several reports of cracking of the elevator ribs at the inboard and outboard ends of the trim tab cut-outs referred to above. To preclude failure of the elevator installation due to cracking of the elevator ribs, accomplish the following:

(a) For airplanes having The Elevator Installation wherein the elevator rib referred to above has not been reinforced by the addition of a .040 inch thick doubler, visually inspect each elevator rib for cracks within 250 hours' time in service after the effective date of this AD and thereafter at intervals not to exceed 250 hours' time in service.

(b) For airplanes having the Elevator Installation wherein the elevator rib referred to above has been reinforced by the addition of a .040 inch thick doubler, visually inspect each elevator rib for cracks within 2,500 hours' time in service after the effective date of this AD, and thereafter at intervals not to exceed 2,500 hours' time in service.

(c) If cracks are found in the affected elevator ribs, before further flight (except that the airplane may be flown in accordance with FAR 21.197 to a base where the alteration or maintenance can be accomplished),

(1) For elevator ribs that are part of The Elevator Installation described in Paragraph (a) of this AD;

(i) Reinforce by the addition of a .040 inch thick doubler and rebalance the affected elevator rib in accordance with McDonnell Douglas Service Bulletin No. 244, Section I dated September 23, 1946 or later FAA approved revision. Thereafter inspect in accordance with Paragraph (b) of this AD;

(ii) Replace the affected elevator rib with an elevator rib made of .040 inch thick material; or

(iii) Modify the affected elevator rib and reinspect in accordance with a method approved by the Chief, Aircraft Engineering Division, FAA Western Region.

(2) For elevator ribs that are part of the Elevator Installation described in Paragraph (b) of this AD,

(i) Replace the affected elevator rib with an elevator rib made of .040 inch thick material; or

(ii) Modify the affected elevator rib and reinspect in accordance with a method approved by the Chief, Aircraft Engineering Division, FAA Western Region.

NOTE: Repetitive inspections of elevator ribs made of .040 inch thick material are not required by this AD but should nonetheless be performed in accordance with good maintenance practice.

This supersedes AD 47-02-10 (21 F.R. 9456).

This amendment becomes effective on May 9, 1968.