#20 – HORIZONTAL STABILIZER TRIM ACTUATOR – ROD END INNER RACES

PROBLEM:

The spherical inner races of the P/N 304426-1 rod ends have been found pulled out or displaced laterally from the outer races of the rod ends on several aircraft. This is occurring primarily on aircraft modified by Service Bulletin 1124-55-107.

Failure of these rod ends could render the aircraft uncontrollable.

CAUSES:

1. The nuts on the P/N 21164-1550 tie rod are being overtightened upon reinstallation during the inspection required by Ch. 5-20-06, para. 1.B. (4), preloading the rod ends inboard.

2. The hardware attaching the rod ends to the P/N 453504-501 lower scissors fitting is not being installed in accordance with Figure 6 of S/B 1124-55-107, which can also cause the rod ends to be preloaded laterally.

CONTRIBUTING FACTORS:

1. Although Ch. 5-20-06, para. 1.B. (4) references 27-40-01 for the inspection procedure, it does not contain a caution or warning notation to avoid overtightening the nuts.

2. The maintenance manual does not provide installation procedures for the actuator upper attaching hardware on aircraft modified by S/B 1124-55-107 (which by now is almost all of the fleet). The parts manual does not show or list the P/N 25W357226-005 bushings or the P/N AN960C816L washers required to properly install the actuator.

RECOMMENDATIONS:

Comply with Service Bulletin 1124-27-151