Edward C. Hodson, W. Lloyd Lane, George S. Moore, James F. Randolph, Leon H. Tanguay

“ An airworthiness directive is being processed as a Notice of Proposed Rule Making. This AD is directed at improving crash survivability on Lockheed Aircraft Service Company Flight Recorders, Models 109C and 109D, as follows: On Model 109C, serial number up to and including S/N 882, and Model 109D, serial numbers up to and including S/N 135, replace the tape cassette with a Lockheed Aircraft Service Company stainless steel cassette, P/N 4024570-1. ”

“ File the remaining edges of the clamp to conform to the contour of the recorder case and install Lockheed Aircraft Service Company clamping ring, P/N 4024582-1. AD action is being considered which will require improvements in the cassettes of the United Data Control and Fairchild flight recorders. Technical Standard Order C-51, Aircraft Flight Recorders, is being revised to incorporate increased crash strength standards. ”

“ The last sentence in Item No. 4 of your letter reads, in part: "... the recorder shall be located as far aft as practicable and shall not be located aft where aft-mounted engines are likely to crush the recorder during impact." The following rewording is suggested as more appropriate: "... the record holder shall be located as far aft as practicable but shall not be located in a position where aft-mounted engines are likely to crush the record during crash impact." ”