Rotorcraft

Tail Rotor Bellcrank Wear

BELL TEXTRON - CAN, 206L-1
SDR # 20120328006

SDR submitted:

During a 100-hour periodic inspection, it was noticed that the tail rotor bellcrank at the end of the tail boom which actuates the pitch change mechanism, had a large amount of axial play causing the bellcrank to "float" within its attachment. Upon removal of the bellcrank for further investigation, it was discovered that the pivot bolt (NAS6604D23) was very loose though the nut was properly cotter pinned. Also once the bellcrank was removed, it was discovered that the washer (AN960-416) under the nut had excessive wear (probably due to the low torque condition).

The bellcrank assembly was thoroughly visually inspected as well as the bushings on the attachment bracket in the tail boom. All items were found satisfactory. However upon reinstallation using new hardware, a discrepancy was noted between the illustrated parts book (IPB) and the installation instructions in the maintenance manual.

The person responsible for maintenance surmises that the excessive wear of the washer was due to the low torque value of the nut causing the clamping of the bellcrank to be loose inside its support bracket. It should be noted that the location of the bellcrank is very hard to access and the torquing procedure is almost impossible to comply with using a standard torque wrench. The attaching hardware has to be tightened by "feel". Once the assembly was properly installed with new hardware and torqued to approximately 40 in/lbs as called out for, the installation was secure with no discernible axial or radial play.

Transport Canada Comments:

Bell helicopter technical publications and product support engineering was notified of the discrepancy. A correction will be made in the next revision of the IPB and the installation instructions in the maintenance manual.

Main Rotor Hub Cracked

SIKORSKY, S76C
SDR # 20120418006

SDR submitted:

During the three year hub visual inspection, a crack was noticed on a damper lug. An eddy current inspection was used to confirm the crack. Main rotor hub replaced.

Transport Canada Comments:

Excellent pick up and diligence by the Aircraft Maintenance Engineer, noteworthy to keep in mind when inspecting this area.

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