47-30-05: Exhaust Stack Inspection

47-30-05 AERONCA: (Was Service Note 2 of AD-759-3 and Service Note 2 of AD-761- 3.) Applies to Models 7AC and 11AC. Inspection required not later than September 15, 1947, and each 50 hours thereafter on Model 7AC airplanes having serial numbers prior to No. 7AC-6797 and Model 11AC airplanes having serial numbers prior to No. 11AC-1697. Due to difficulties in the manufacture of the exhaust stacks for these airplanes, it is necessary to inspect the stack "Y" junction for evidence of failure or deterioration. This inspection should be accomplished as follows: A. Initial inspection (not later than September 30, 1947). The exhaust stacks on these airplanes should be removed from the airplane and checked visually in the vicinity of the "Y" junction for evidence of burning or flaking, tapped with a hammer for evidence of soft spots, and inspected to determine whether the stack is obstructed in any way. B. Periodic inspection (each 50 hours). The exhaust stacks should be reinspected visually in the vicinity of the "Y" junction by removing the cabin and carburetor heater muffs each 50 hours of engine operation. (This information is also contained in Aeronca Service Helps and Hints No. 25 dated May 13, 1947.)