Part 71, page 336

Transcript

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INTRODUCTION

Reference (a) specified that the aft airstairs should be released in flight and allowed to free-fall without utilizing hydraulic power, simulating an in-flight failure of the airstair up-latch. In addition, it also specified that the airstair should be extended by utilizing normal hydraulic power. The aerodynamic characteristics of the extended airstair and the associated effects on airplane performance and handling were also to be evaluated at speeds up to V_MO.

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The initial evaluation was conducted on Test 100-1, with most of the produc- tion airstair cavity panels removed. They were removed to avoid the possi- bility of panel failure causing damage to wiring and tubing in the area, in the event large pressure differentials should occur. Testing was done with flaps at 25 degrees and a nominal airspeed of 125 knots, with the airstair allowed to free-fall and also extended with hydraulic power. In addition, with the aft airstair free-floating, the flaps were retracted and the air- plane was accelerated to V_MO. The testing was repeated on Test 100-3 with all the production airstair cavity panels installed, with the exception that no hydraulic airstair extension was attempted. In addition, two un- successful attempts were made to release the airstair and allow it to free- fall at an approximate airspeed of 300 knots.

Both tests were conducted from Boeing Field, Seattle, on Airplane N72700. Boeing pilots, Mr. J. Waddell and Mr. S. L. Wallick, conducted Test 100-1, with Boeing Test Engineer, Mr. R. F. Brown, operating the aft airstair. Test 100-3 was conducted by Boeing pilots, Mr. J. Waddell and [REDACTED] [REDACTED] with Boeing Test Engineer, Mr. C. M. Clark, operating the airstair.

DECLASSIFIED

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CONFIGURATION

Model 727-22, Airplane N72700, was in production configuration as detailed in Reference (b) except for the removal of the production airstair cavity panels during Test 100-1 and the removal of the airstair spring-loaded latch stop during both tests. In addition, FC 751-1-1 was incorporated on the airplane for both tests. This FC provided a cable to restrain the airstair to a maximum extension of 25 degrees and thus prevent airstair damage during landing in the event the stair could not be retracted in flight.

The airplane cabin was depressurized during both tests, with the ram air valve closed, both air conditioning packs off, and the manual pressure con- troller in full decrease pressure.

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INSTRUMENTATION AND DATA REDUCTION

A Pulse Duration Modulation (PDM) magnetic tape system and a photorecorder were used to record performance and calibrated data. Airspeed and altitude were measured using the pilots' production pitot-static system. The aft airstair was instrumented to measure position in degrees from the up and locked position. The static pressure in Section 48 was measured by a pick-up that was located on the LH side of the airplane, outboard of the LH cavity side panels. Airplane cabin pressure and rate of climb were recorded on the

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DB Cooper-30621

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TD 1546 L-R3 ERAEBNNE NO. D6-7771 Sec. 1.21.19 PAGE 3

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b6 b7C