AD 73-08-01

73-08-01 BOEING VERTOL: Amendment 39-1618 as amended by Amendment 39-2120. Applies to all 107-II type helicopters.

Compliance required as indicated unless already accomplished.

In order to detect surface defects which can cause complete failure of the P/N 107D2067 aft transmission quill shaft, accomplish the following:

1. Within 25 flight hours after the effective date of this AD, inspect and code mark, in accordance with paragraph 3, all P/N 107D2067-1 or -3 quill shafts having 600 hours total time except those quill shafts specified in Service Bulletin A107-320, Revision C.

2. Quill shafts with less than 600 hours total time, except those quill shafts specified in Service Bulletin A107-320, Revision C, must comply with paragraph 3 prior to accumulating 600 hours total time in service.

3. Strip quill shaft at the .375 inch diameter pin hole; inspect under microscope magnification, code mark acceptable units with suffix letter "R" and apply surface treatments in accordance with Boeing-Vertol Telex 8-1420-1-291 dated 16 November 1972, or Service Bulletin No. A107-320 dated April 30, 1973, and subsequent approved revisions, or an equivalent procedure approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. Inspect for surface pits, arc burns and cracks. Replace any quill shaft which has surface pits, arc burns or cracks with a shaft which has been inspected in accordance with this paragraph or a shaft referenced in Service Bulletin No. A107-320, Revisions A and C. (Boeing-Vertol Service Bulletin Nos. A107-320A, A107-320B and A107-320C, and Boeing Vertol Telex Nos. 8-1420-1- 268 and 8-1420-1-254 and available specimen photographs pertain to this subject.)

Amendment 39-1618 was effective April 9, 1973. This amendment 39-2120 is effective March 11, 1975.