57-20-04: Landing Gear Retraction Jack

57-20-04 VICKERS: Applies to All Viscount 700 Series Aircraft Equipped With 14-Inch Stroke Oleos. Compliance required as indicated. As a result of investigations and tests by Vickers it has been found necessary to limit the life of the trunnion pins and bearing bolts of the main landing gear retraction jack (cylinder) assembly, right and left, Drawing No. 77450 sheet 7. Accordingly, Vickers-Armstrong insured the following corrective measures with concurrence of the British Air registration Board. The FAA concurs with this action and considers compliance therewith mandatory: 1. At the ram end of the retraction jack, attached to the landing gear actuating lever assembly, replace the trunnion fork end P/N 74450-99 and pin P/N 7450-101, at 2,500 flights; and bearing bolt P/N 74450-103 at 5,000 flights. On aircraft that have exceeded 2,500 flights a precautionary visual inspection for cracks on the trunnion P/N 74450-99 is required at the next daily inspection with particular attention being paid to the flat surfaces. If cracks are found the trunnion and pin and bearing bolt must be replaced before further flight. If no cracks are found, aircraft may continue flying provided the trunnion is visually inspected for cracks at every daily check until replaced. 2. At the retraction jack cylinder end, attached to structure joint assembly, replace the trunnion block P/N 74450-79, pin P/N 74450-81 and bearing bolt P/N 74450-341 or 74450- 83 at 7,000 flights.