Atlas Air 3591 NTSB Public Docket Opened

[Airbubba]

Originally Posted by StudentPilot479

Just a GA pilot here, but if the two yokes were going opposite ways, why does the captains yoke shear pin break and why not the shear pin on the first officer's yoke?

Originally Posted by Dogsofwar

when the shear pin breaks the control columns operate the elevators of there respective sides, so in this instance the FO’s elevator would have been deflected down whist the Capt who was pulling back would have deflected his upwards, once the fo realize what was actually happening he then was able to pull nose up on his!

I don't believe there is any shear pin involved in a 767.

From my earlier post on a closed thread:

Here's a description of the B-763 control column operation with one side jammed from page 12 of the MS990 NTSB accident report:

The captains and first officers control columns have authority to command full travel of the elevators under most flight conditions and normally work together as one system. However, the two sides of the system can be commanded independently because of override mechanisms at the control columns and aft quadrant. Therefore, if one side of the system becomes immobilized, control column inputs on the operational side can cause full travel of the nonfailed elevator. In addition, in many cases, control column inputs on the operational side can also result in nearly full travel of the elevator on the failed side through the override mechanisms. The elevator PCAs are installed with compressible links located between each bellcrank assembly and PCA input control rod to provide a means of isolating a jammed PCA, thus allowing the pilots to retain control of that elevator surface through its two remaining (unjammed) PCAs

From the Performance Report in the recently released docket:

Figure 7 shows an elevator split between the left and right sides of the airplane: the left elevator is associated with the captain in the left seat, and the right elevator is associated with the first officer in the right seat. The elevator deflections are similar until about 1238:46. At that time, the first officer is heard asking a question about airspeed on the CVR, and the elevators begin to split: the captain begins to pull from 2˚ to 8˚ more ANU elevator than the first officer. The split continues until about 1238:56, about one second after the airplane would have broken out of the reported 3,500 ft cloud layer. Both the captain and the first officer subsequently commanded ANU elevator until impact. (The normal load factor recorded by the FDR in Figure 6 is greater than 4g right before impact.)

There was an earlier rumor of a -4g load factor on the pitchover, this was apparently a typo (or an exaggeration).