47-21-09 NAVION: (Was Mandatory Note 8 of AD-782-3.) Applies to All Serials Up to and Including Number NAV-4-947.
Compliance required prior to September 1, 1947.
Due to malfunctioning of the hydraulic system which has resulted in the failure of components of that system, including actuating cylinders, the following modifications must be accomplished:
(a) If an engine-driven hydraulic pump is installed in the airplane, rework the hydraulic power system to install the manually controlled relief valve, North American P/N 145- 58027, and replace the existing placard "Hyd. System Pull Off" with new placard "Hyd. Power On".
(North American Field Service Bulletin No. 26 covers this same subject.)
(b) Install the swivel head type nose gear actuating cylinder, North American P/N 145-58014.
(North American Field Service Bulletin No. 19 covers this same subject.)
(c) Visually inspect all flap and landing gear actuating cylinders for evidence of cracks or other damage. Any cylinders found to be damaged should be replaced.