Page:NTSB Aircraft Accident Report, United Airlines Flight 389.pdf/20

 Several pieces of air distribution and air conditioning ducting were recovered. This ducting was installed overhead in the fuselage area. There was no soot or fire damage on these pieces of ducting. Both engine bleed air valves were found in the open position. The components which make up the cabin pressure control were recovered. The rate of climb indicator was intact in the panel but the pointer was detached from the shaft. The differential pressure gauge was intact. The cabin altitude pointer was on 30,000 feet and the cabin differential pointer was set at approximately 6.3 psi. The automatic cabin controller was recovered intact with the cabin altitude pointer on l,OOO feet. The rate selector knob was turned to "decrease" and the barometric setting in the window was 29.29. The setting of the flight altitude and maximum differential in the window was between 24,OOO-25,000 feet. The manual cabin pressure control pointer was in the center of the automatic range. Only the top covers of the two outflow valves were recovered.

The automatic pilot control panel was recovered with the mode selector switch in manual, the integrated command knob slightly left of center in the turn mode and neutral in the pitch mode, the aileron and elevator engage switches in a mid-position between "engage" and "disengage," and the altitude hold switch "off."

The automatic pilot stabilizer trim servo assembly was tested and no discrepancies were found. The left and right elevator position and trim sensors were bench-checked and found to be O.6° and 3.4° off zero, respectively.