Part 71, page 335
Document date 7 May 1964
FBI 164-81, Vault Part 71 p. 335 (DB Cooper-30620), Report, dated 7 May 1964, serial FC 751-1-1 (as read from the transcript) — cooper.theunsolved.net/parts/Cooper-Part-71/pages/335
Transcript
The scan is the source; the transcript is machine-generated from it.
SUMMARY
This report presents the results of tests conducted on the Model 727 airplane to evaluate the characteristics of the aft airstair when extended inflight and the associated effects on airplane performance and handling. The airstair was extended both by allowing it to free- fall and by utilizing normal hydraulic power. These extensions were made with the airplane trimmed for level flight at 125 knots and flaps at 25 degrees. The airstair extended a nominal 8.5 degrees when allowed to free-fall and it required only approximately one-tenth unit of nose-down trim to compensate for the stair. The stair extended a nominal 13.5 degrees with hydraulic power and this caused approxi- mately a three-tenths unit nose-down trim change. The airplane was also accelerated to V_MO with flaps up and the airstair free-floating. The airstair was quite stable when it was down and no airplane control problems were experienced. No excessive cabin pressure transients were noted with the aft entry door open and the stair extended. The environment near the aft entry door allowed it to be safely opened and the stair retracted at speeds up to 300 knots. At 300 knots, it was also found that the airstair would not free-fall when unlatched.
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125 KNOTS 25° DOWN FLAPS
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DB Cooper-30620
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TD 1566 L-R3 EVIDENCE | NO. D6-7771 Sec. 1.21.19 | PAGE 2