Page 60: Fifteen-day and fifty-hour inspection

PAGE 60 / Fifteen-day and fifty-hour inspection

RESTRICTED

5. 15 Day Inspec- tion

Inspect gyro rotor bearings each 15 days when gyro has been operated less than 15 hours in 15 days. Oil if necessary. See 15 Day Insp. Main- tenance, Sight for further instruction.

6. Fifty Hour Inspec- tion

a. Case or Housing N.O.P. #650 C.L.I. 42-26

1. The case must be kept clean and dry to prevent corrosion. Check condition of paint as to peeling, chipping, etc. If the paint has been chipped or has peeled but no corrosion formed, scrape and polish area with a hard wooden stick and crocus cloth and retouch with a fast drying crackle finish lacquer on the exterior, and black mat finish on the interior. If corrosion has formed underneath paint, scrape and polish area thoroughly before retouching. Corrosion of the magnesium alloy in the equipment may be detected as a white powder or paste similar to the sub- stance which is found on a "dead" dry cell bat- tery. It must be removed completely by scraping it away to the bare metal. Retouch with black paint or run in a small amount of bombsight oil if no paint is available.

2. Check for corrosion around screw heads. If corrosion is found it is the case, not the screw, that is corroded; all screws are either brass or stainless steel. Too much emphasis can- not be put on the fact that most screws are small, soft, and the threads are delicate, both on the screw and in the hole. Always remember that you are working on an extremely delicate instrument. To avoid corrosion of screw holes, dip each screw in light oil before replacing. Do not dip the screw in your mouth.

3. If the case is dented or cracked to such an extent that the operation of any unit is im- paired, the condition should be reported to Chief A. F. Maintenance Command and method of dispo- sition requested.

4. Remove dirt from interior of case with alcohol moistened cotton and swab stick. NEVER TRY TO BLOW THE DUST AND DIRT FROM THE INSIDE OF THE CASE.

5. Check for corrosion and rust on the bare metal. Remove corrosion with acid-free kerosene and crocus cloth. Clean the surface thoroughly with benzine and dry with a clean white cloth. Use of clean white cloths in connection with this equipment is stressed, due to the fact that the dye from colored cloth may easily be deposited upon the surfaces with which it comes in contact