55-26-02 THOMPSON ENGINE DRIVE FUEL PUMPS: Applies to All Thompson TF-1100-2 and TF1100M2 Pumps.
Compliance required as indicated.
To prevent TF-1100 fuel pump failure resulting from excessive drive pin wear, accomplish the following:
1. Remove pump from certificated airplanes and replace with Thompson TF-1900 pump having larger diameter drive pin not later than August 1, 1956. TF-1100 pumps may be converted to TF-1900 pumps when modified in accordance with Thompson Service Bulletin ESD-182A and Amendment ESD-182B.
2. Until installation of the TF-1900 pump, the drive pin (Thompson Part No. TF-1191) in the TF1100 pumps should be replaced with an unused pin at the next 100-hour aircraft inspection and each 100 hours thereafter. At the time of pin replacement, inspect the drilled hole in the TF-1100 rotor for excessive elongation and, if necessary, replace rotor.
(Thompson Products Service Bulletin ESD-176A covers this same subject.)
This supersedes AD 55-19-02.