49-31-01 BEECH: Applies to Models 35 and A35 Aircraft, Serial Numbers D-1 to D-1935, Inclusive, Equipped With Hand Emergency Fuel Pumps Which Have Not Been Modified to Incorporate the Double "O" Ring Shaft Seal, Beech P/N 35-924070.
Compliance required not later than October 1, 1949, and each 100 hours of aircraft operation thereafter.
To prevent possible hazardous loss of engine power resulting from introduction of air into the airplane's fuel system, inspect the hand emergency fuel pump installation for indications of a defective "O" ring shaft seal. A defective shaft seal may be indicated by fluctuating engine fuel pressure, fuel fumes in the cabin or evidence of fuel leaks around the hand pump's shaft. If a defective shaft seal exists, accomplish proper repair or replace the single "O" ring shaft seal with the double "O" ring shaft seal, Beech P/N 35-924070. After the double "O" ring shaft seals are installed, the 100-hour inspection is no longer required.
(Beech Service Bulletin Model 35, No. 14, Model A35, No. 5 dated July 6, 1949, covers this same subject.)