Part 71, page 339

Transcript

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RESULTS AND DISCUSSION (Continued)

latching the aft entry door at the airspeed of approximately 300 knots. No further pictures of tuft activity were taken on this test. Since no large pressure surges had been recorded in the cavity during Test 100-1, all of the production airstair cavity panels were installed during Test 100-3. No panel movement or oil-canning was noticed during the test, and no panel failures were noted after landing.

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CONCLUSIONS

No unusual control or handling problems should be experienced if the aft airstair should accidentally extend inflight. In fact, from the results obtained during Test 100-3, if the up-latch failed at normal cruise speed, the aft airstair would probably not extend until the airplane slowed down to some airspeed below 300 knots. The control handle would be expected to remain in its normal UP position, because the detent provides a positive stop. Thus, the first indication of latch failure would occur when the airstair extended far enough to operate the stair warning light microswitch located at the aft end of the cavity. Since the airstair might contact the runway as the airspeed decreased after landing, the aft entry door could be opened and an operator could safety initiate stair retraction. Provided there was no structural interference from a failed roller or up-latch, the airstair should retract. However, it would be necessary to hold the control handle in the RETRACT position and keep the trigger depressed, because the system is depressurized when the control handle is in the UP position.

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DB Cooper-30624

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TD 1546 L-R3 BOEING NO. D6-7771 Sec. 1.21.19 PAGE 6