50-10-02 NAVION: Applies to all Airplanes, Serial Numbers NAV-4-2 Through NAV-4- 1790.
To be accomplished as indicated below.
The above aircraft employ flexible hose, Ryan Drawing 145-42202, between the exhaust shroud and the carburetor heat valve. This hose has shown a tendency to deteriorate with age and may collapse, resulting in a considerable loss of engine power.
An inspection of these hoses should be made not later than March 20, 1950, and after each 25 hours of aircraft operation until replacement is made with the hose mentioned below. All hoses found to be in poor condition should be replaced immediately by wire reinforced hose. Arrowhead Rubber Co. hose type 8AX (Ryan Drawing No. 145-42202-3) or equivalent is satisfactory.
The installation of the above wire reinforced air intake hose in replacement of the original hose should be accomplished in all aircraft by September 1, 1950.
(Ryan Service Letter No. 67 dated February 7, 1950, also covers this subject.)