Part 71, page 337

Transcript

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INSTRUMENTATION AND DATA REDUCTION (Continued)

photorecorder. Instrumentation calibrations and configurations will be found in Reference (e). White tufts were installed on the aft airstair and adjacent bulkheads and some photographs of tuft activity were taken during Test 100-1 (Pages 7 through 9 ).

The PDM magnetic tape data were reduced by the IBM 7090 computer using the Basic Airplane (BA), Engine Performance (EP), and Calibrated Data (Calib.) programs. The procedures are outlined in Reference (f). The computer output data are filed in Reference (c). Photorecorder data were manually reduced and the tabulated results are filed in this report. (Pages 13 through 23).

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RESULTS AND DISCUSSION

The aft airstair control system was in production configuration for both Test 100-1 and 100-3, except for removal of the spring-loaded latch stop. The latch stop was removed to permit moving the control handle to the UP position with the airstair down, thus simulating a condition which could exist if the up-latch failed inflight. With the airstair down and the control handle in the UP position, both the UP and DOWN side of the stair actuator are connected to the system return line through the control valve, allowing the airstair to free-float. The control handle was in the UP position during all test conditions, except for stair extension and retraction and the stair extension utilizing hydraulic power.

The sequence during Test 100-1 (Reference (d)) started with the airplane trimmed for level flight at 10,000 feet altitude and 125 knots airspeed, flaps at 25 degrees, cabin depressurized, and the airstair up and locked. With the operator wearing a parachute and secured by a restraining strap, the aft entry door was opened. No difficulty was experienced in opening the aft entry door and the operator then moved the upper control handle to the DOWN position without depressing the handle trigger. Thus, the air- stair was unlocked and allowed to free-fall. After the stair started to extend, the control handle was moved to the UP position and the stair was allowed to free-float. No noticeable out-rush of cabin air was experienced when the stair extended and only a one-tenth unit nose-down trim change was required to counteract the airstair floating down approximately 8.5 degrees. The aft entry door was allowed to remain open and a photograph of tuft activity was taken after the airplane stabilized on this condition (Page 7 ). The tuft picture appears to indicate some airflow into the cabin.

With the flaps still at 25 degrees and at approximately 125 knots airspeed, the airstair was successfully retracted and the uplatch secured by moving the control handle from the UP to the RETRACT position, depressing the handle trigger, and moving the handle back to the UP position after the airstair was fully retracted. The next condition involved extending the stair utilizing hydraulic power. The control handle was moved from the UP to the DOWN position with the handle trigger depressed. With hydraulic

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DB Cooper-30622

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TD 1546 L-R3 BOEING NO. D6-7771 Sec. 1.21.19 PAGE 4 4-7000