NTSB Identification: ATL98IA039.
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Incident occurred Thursday, January 22, 1998 in MIAMI, FL
Probable Cause Approval Date: 02/16/2001
Aircraft: Robinson R-44, registration: N972SA
Injuries: 1 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

According to the pilot, as he was attempting to land, he was unable to apply left cyclic. The pilot made a run-on landing, using right turns, without further incident. Further examination of the cyclic revealed that the lateral trim actuator shaft was worn and lodged in the guide bearing, thus interfering with the surrounding structure. After this incident, the inspection criteria for the lateral cyclic trim system was reviewed. The criteria did not include a measurement of the shaft wear. There was a service bulletin, SB-19, that dealt with excessive shaft wear on Robinson R-44 helicopters, but it did not apply to the incident helicopter. Subsequent to this incident, a new Service Bulletin, SB-26, was released for R-44 helicopters, which stated that the lateral cyclic trim assembly shaft, P/N C585-1, should be measured in several places. If the shaft diameter varies more than 0.004 inches in any 0.50 inch of length, the assembly should be replaced before further flight. After the release of SB-26, a priority Airworthiness Directive (AD), AD 98-04-12, was issued to require compliance with the terms of SB-26.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

An inadequate service bulletin which did not require measurement of the cyclic trim assembly shaft and did not identify all helicopters in which shaft wear could lead to restricted movement of the lateral cyclic trim.

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