AD 85-23-04

85-23-04 McDONNELL DOUGLAS (Douglas Aircraft Company): Amendment 39-5162. Applies to all McDonnell Douglas Model DC-4 and C54-DC series, and all C54 military models eligible or to be made eligible for civil use, certificated in any category. Compliance required within 100 flight hours time in service after the effective date of this AD, unless previously accomplished.

To prevent loss of the elevator trim tab control in flight, accomplish the following:

A. Perform a dye penetrant inspection for cracks in the left-hand and right-hand elevator trim tab spars as station 81.5 (approximately), in accordance with the instructions of paragraph D. of this AD. Note that AD 48-06-05 requires, in part, the replacement of an originally designed aluminum control horn P/N 2114427, with a steel control horn, P/N 2357165.

B. If no cracks are found in the trim tab spar, rework and reinstall the steel control horn (previously identified as P/N 2357165) in accordance with the instructions of paragraph D. of this AD.

C. If cracks are found in the trim tab spar, accomplish prior to further flight: (1) the rework to the control horn in accordance with the instructions of paragraph D. of this AD, and (2) a repair of the cracked spar. McDonnell Douglas Service Rework Drawing J060262 Revision B, dated January 30, 1985, or equivalent approved by the Manager, Western Aircraft Certification Office, FAA, Northwest Mountain Region, describes an acceptable means of repair.

D. Instructions for inspection of spar and rework of control horn:

1. Remove elevator trim tab in accordance with DC-4 Maintenance Manual (M/M) Flight Control Group, paragraph 3.15.1.

2. Remove elevator trim tab control horn, P/N 2357165, from trim tab spar station 81.5 (approximately).

3. Strip top coat and primer from the area of the spar at station 81.5 (approximately) in accordance with normal shop practice.

4. Using dye penetrant procedures, inspect for cracks in thetab spar radius in accordance with normal shop practice.

5. Rework the steel control horn base by chamfering the upper and lower edges to 0.06+0.03 inches x 45 degrees + 5 degrees and leave no sharp edges.

6. Protect the worked areas with two applications of zinc chromate primer or equivalent.

7. Reinstall flight control system components in accordance with DC-4 M/M Volume VI, paragraph 3.15, Elevator Trim Tab.

8. Required fastener hardware, their torque valves, and torque slippage indication instructions are given in the DC-4 M/M, DC-4 Service Bulletin #83 and AD 51-09-02.

NOTE 1. If a DC-4 M/M is not available, the equivalent section of the C-54 M/M may be used.

NOTE 2. Repetitive inspections, the attachment fasteners with their torque valves, and torque slippage indication requirements of Airworthiness Directives AD 48-06-05 and AD 51-09-02 remain applicable and are not intended to be changed by the requirements of this AD.

E. Prior to issuance of a Certificate of Airworthiness for military aircraft being converted for civil certification, the airplane must be inspected, parts reworked, and if cracks are found, a repair accomplished, in accordance with the requirements of this AD.

F. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of inspections required by this AD.

G. Alternative inspections, modifications, or other actions which provide an acceptable level of safety may be used when approved by the Manager, Western Aircraft Certification Office, FAA, Northwest Mountain Region.

All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to the McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Director, Publication and Training, C1-750 (54-60). These documents may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or at 15000 Aviation Boulevard, Hawthorne, California.

This amendment becomes effective December 5, 1985.