Part 71, page 338

Transcript

The scan is the source; the transcript is machine-generated from it.

RESULTS AND DISCUSSION (Continued)

pressure on the DOWN side of the actuator, the airstair initially extended to approximately 14 degrees and then retracted slightly, probably because of compression of the lower struts. Three-tenths of a unit nose down trim change was required with the airstair in this position, but no control problems were experienced (Reference tabulation on Page /0 ). The aft entry door was open throughout this condition and another picture of tuft activity was taken (Page 8 ). This picture is not as clear as the first because the flash bulb failed to operate.

Following this, the control handle was returned to the UP position, allowing the airstair to free-float, and the aft entry door was closed. The flaps were then retracted to zero and the airplane retrimmed at approximately 200 knots airspeed and 10,000 feet altitude. Engine power was then increased to MCT and the airplane was accelerated to VMO, re- trimming each time the stick force reached approximately 20 to 30 pounds. The free-floating stair oscillated a maximum of 1.5 degrees during the acceleration, but no extreme bouncing was observed (Reference plot on Page // ). No control problems were experienced during the acceleration, and the airstair slowly retracted as the airspeed increased. Another picture of tuft activity at VMO was taken through the aft entry door window (Page 9 ). Although the field of view is quite restricted, again the tufts appear to indicate some airflow into the cavity. This inflow of air was also noticed when the aft entry door was unlatched at VMO and some inflow of air was noted around the door seals. The door was again latched and the airplane decelerated to approximately 260 knots airspeed, at which time the aft entry door was easily opened, the aft airstair was again successfully retracted and latched, and the entry door closed.

The procedure during Test 100-3 was the same as Test 100-1, except that the airstair was not extended using hydraulic pressure. In addition, the airplane was being continually retrimmed during the acceleration to VMO, making it easier to hold a nearly constant altitude (Reference plot on Page /2 ). An additional condition was also conducted during this test: namely, two attempts were made to unlock the airstair and allow it to free-fall at an airspeed of approximately 300 knots. This condition was done after accelerating to VMO with the stair down. The aft entry door was easily opened at this airspeed, again noting a slight inflow of air into the cabin. The airstair was successfully retracted with hydraulic power and the control handle moved to the UP position to lock the stair. Following this, the handle was moved to the DOWN position, without depressing the handle trigger, to permit the stair to free-fall. Although the uplock was visually observed to rotate and release the stair and the pilot reported that the warning light in the control cabin indicated the stair was unlocked, the air load prevented the stair from extending. A second attempt was made at this airspeed, after first returning the control handle to the UP position and then positioning it to DOWN. The same results were obtained. The test was concluded by again closing and

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DB Cooper-30623

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TD 1546 L-R3 BOEING Sec. 1.21.19 NO. D6-7771 PAGE 5 L-7000