Borescope Extension Tubes I, II, and III

ARMY

TM 9-6650-235-13&P

MARINE CORPS

TM-08552A-13&P

c. Borescope Extension Tubes I, II, and III. Three

borescope extension tubes are provided, each consisting

of a forward (1) and a rear (2) section. They permit

inspection of the longest weapons encountered. The

borescope extension tubes are numbered with Roman

numerals (I, II, and III). These tubes have a lock

assembly on one end and a hole on the other end to

receive the key on the lock assembly of the next tube

section. The forward sections of the extension tubes are

identical (as are the rear sections) except for the

graduations on the outside of the tubes. The tubes have

graduation marks of 1.0 inch, 6.0 inch and 1.0 foot

intervals (up to 26 feet) with the 6.0 inch and 1.0 foot

marks completely encircling the tube. A line runs within

4.0 inches of the length of the tube through the center of

the graduation intervals to assist in the assembly of the

sections and to provide a reference point for stating the

o'clock position of cannon bore defects. The specific

order of assembly between the objective tube assembly

and adapter tube assembly is borescope extension tubes

I, II, and III.

BORESCOPE EXTENSION TUBES I, II, & III

1-3