[911/914gary]

I agree with MFAA that the scissor link or torque links are attached and that steering would be inoperative. The torque links are attached with cross bolts. This would not be removed by grounds crew.

Being involved with the landing gear engineering I have come across some inside info. There is a history of these nose gear failures.

The shock absorber assembly consists of two sections: a stationary inner cylinder (piston), which is mounted inside the shock strut assembly, and a sliding tube, which is the lower portion and contains the wheel axle. The upper portion of the inner cylinder contains anti-rotation lugs. During installation of the shock absorber, the anti-rotation lugs are aligned in slots on a backplate, which is mounted inside the top of the shock strut. A nut is then installed to secure the inner cylinder of the shock absorber/gear assembly to the backplate.

The bottom of the inner cylinder contains the lower cam. The upper part of the sliding tube contains the upper cam. This cam is held in place by eight dowel pins retained by a bushing and a retaining ring. During gear extension and retraction, the sliding tube extends down and the two cams engage, centering the nose wheel. When the strut is compressed on the ground, the cams are separated and the nose wheel is free to move for on ground steering.

Apparently if the mechanics are not careful the strut’s upper cam can be assembled with the dowel pins miss-aligned and still have steering if the strut is compressed. Because the cam is not secure the cam can rotate during steering operation. When the aircraft rotates the upper cam can react with the lower cam and shift the strut back to the proper position and center the steering. However , if the cam's shift is great enough, it is also possible to react with the lower cam by rotating the strut 90° out of phase. This is what has happened in 8 previous incidents!