Page:CAB Accident Report, United Air Lines Flight 823.pdf/20

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Mr. Leon H. Tanguay Director, Bureau of Safety Civil Aeronautics Board Washington, D. C. 20428

Dear Mr. Tanguay:

This is in reply to your letter of July 17, 1964, reference B-80-96, concerning Federal Aviation Agency action on flight recorder improvements. The following outlines the current status of Agency action:

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.

On Model 109C, up to and including S/N 889, saw off near the case the two latch clamps which are to the left of the pitot pressure line connector when facing the pitot pressure connector. 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. Regulatory documentation leading to issuance of 