56-27-04 NAVION: Applies to B Type Aircraft Equipped with Reading Aviation Service Inc. or Hackenberk Sales and Service Downdraft Cooling Kit Installations.
Compliance required not later than July 1, 1957.
Engine cooling tests conducted subsequent to the installation of these kits reveal that cylinder head and oil temperature values can exceed established limits. To prevent serious damage to the engines in these aircraft due to overheating, one of the following alternate actions is necessary.
1. Remove Reading Aviation Service Inc. or Hackenberg Aviation Sales Service downdraft cooling kit and return aircraft to the original Ryan cooling configuration, or
2. Modify the Reading or Hackenberg engine cooling kit in accordance with Reading Aviation Service Inc. Service Bulletin No. 1 dated July 26, 1956.