# NTSB ATL98IA039: Robinson R-44, N972SA, Miami, FL, January 23, 1998 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: January 22, 1998, 22:30 local (Jan 23, 1998, 03:30 UTC) - Place: Miami, FL - Coordinates: 25.649188, -80.410339 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=25.6492&lon=-80.4103&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 16, 2001 - Report: Approved by Office Director - ADs cited in the narratives: [AD 98-04-12](https://openairdocs.org/ad/98-04-12) (OpenAirDocs) - NTSB case key (mKey): 3937 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL98IA039 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/3937/pdf - Page: https://openairdocs.org/ntsb/ATL98IA039 ## Probable cause 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. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, hover - rotorcraft flight control system,cyclic trim - movement restricted (cause) - maintenance,service bulletin/letter - inadequate, manufacturer (cause) ## Analysis 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. ## Factual narrative On January 22, 1998, about 2230 eastern standard time, a Robinson R-44 Helicopter, N972SA, experienced a partial cyclic control stick failure while hovering to land at the Kendall-Tamiami Executive Airport, Miami, Florida. The helicopter was operated by the pilot under the provisions of Title 14 CFR Part 91, and visual flight rules. Visual meteorological conditions prevailed, and no flight plan was filed for the local, personal flight. The private pilot was not injured, and the helicopter sustained no damage. The flight departed Fort Lauderdale, Florida at 2200. According to the pilot, as he was attempting to land, the helicopter began to drift right. He applied left cyclic control, but "just past the center of cyclic movement, the cyclic felt as if it hit a stop". The pilot rotated the cyclic 360 degrees to ensure the cyclic was not set at full right trim. There was no effect. 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 not properly aligned. The shaft exhibited wear concurrent with its position in a guide bearing. After sufficient quantity of the shaft was worn, the shaft became lodged in the guide bearing. Once lodged, the lower end of the shaft and a guide spring became loose and interfered with the surrounding structure, resulting in the partial loss of lateral control. 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 which directed mechanics to replace the lateral cyclic trim assembly shaft, Part Number (P/N) C585-1, if the diameter was decreased 0.001 inch per 100 hours or a diameter of less than 0.238 inch. This Service Bulletin, however, was for R-44 helicopters Serial Numbers (S/N) 0002 through 0321, and it did not apply to the incident helicopter. Subsequent to this incident, a new Service Bulletin, SB-26, was released for R-44 helicopters, S/N 0002 through 0420 and 0425, 0426, and 0427. SB-26 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. ## Aircraft - Registration: [N972SA](https://openairdocs.org/aircraft/N972SA), registered now, S/N 0394 (OpenAirDocs) - Reported make and model: Robinson R-44 - Registry model: [Robinson Helicopter R44](https://openairdocs.org/model/robinson-helicopter-r44) (registry code 7640120) (OpenAirDocs) - Registry engine: [Lycoming 0-540 series](https://openairdocs.org/engine/lycoming-0-540-series) (registry code 41532, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 0394 - Airframe hours: 64 - Engines: Lycoming O-540-F1B5 235 horsepower reciprocating - Damage: No damage - Flight: Personal, Part 91 - Operator: Spencer Gordon - Registered owner: Sunshine Aviation Leasing, Inc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, November 15, 1997, 64 hours before - Departed: FLL, FORT LAUDERDALE, FL - Airport: TMB, Kendall Tamiami Executive ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; private; airplane ratings: single-engine sea, multi-engine land, single-engine land; medical: class 1, valid medical--w/ waivers/lim; seat: right; flight hours: 4,500 total, 55 in this make and model, 3,400 as pilot in command, 90 in the last 90 days, 30 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 130° at 8 knots, gusting 18 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 64 °F - Altimeter: 30.00 inHg - Observed at: MIA, 10 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 19980122003509I](https://openairdocs.org/incident/19980122003509I), Jan 22, 1998: Robsin R44, Miami, FL. Narrative: on January 22, 1998, about 2230 eastern standard time, a Robinson R-44 helicopter, N972SA, experienced a partial cyclic control stick failure while… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.