On March 11, 1998, a Boeing 737-205 (registration N733AR) operated by Arco Alaska, Inc. was involved in an aviation accident near Anchorage, AK. No fatalities were reported. Investigators recorded the probable cause as: Loss of grease to the yaw rate gyro spin bearings, and corresponding damage to the spin and gimbal bearings. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
While parked at the gate, an airplane experienced rapid rudder oscillations that shook the entire aircraft. Post-incident testing found the oscillation was limited to yaw damper authority and caused by loss of grease and damage to the yaw rate gyro bearings.
Incident
During parking at the gate, the airplane's rudder began a rapid oscillation that caused the entire airframe to shake. No corresponding movement of the cockpit rudder pedals was observed.
Investigation
Postincident testing determined that the rudder was oscillating approximately 1.5 degrees on either side of the centerline. The oscillation was confined solely within the authority of the yaw damper system. Further examination revealed a loss of grease on the yaw rate gyro spin bearings, along with corresponding damage to the spin and gimbal bearings. The yaw damper coupler and gyro assembly had accumulated 24,850 hours in service prior to the event. The testing concluded that the rudder movement was produced by the yaw damper itself, as no other cause was identified.
Probable cause
Loss of grease to the yaw rate gyro spin bearings, and corresponding damage to the spin and gimbal bearings.
What happened in the 11 Mar 1998 Boeing 737-205 accident near Anchorage, AK?
While parked at the gate, an airplane experienced rapid rudder oscillations that shook the entire aircraft. Post-incident testing found the oscillation was limited to yaw damper authority and caused by loss of grease and damage to the yaw rate gyro bearings.
Were there any fatalities in the 11 Mar 1998 Boeing 737-205 accident?
No fatalities were recorded in this accident.
What aircraft was involved and where did it happen?
The accident on 11 Mar 1998 involved a Boeing 737-205, registration N733AR, operated by Arco Alaska, Inc., at Anchorage, AK.
What was the probable cause of the accident?
Loss of grease to the yaw rate gyro spin bearings, and corresponding damage to the spin and gimbal bearings.
A SkyWalk Join't 3 paraglider crashed into the ground near Las Vizcachas, Chile, on September 1, 2024. The pilot and passenger sustained serious spinal…
PARAPENTE (ULTRALIVIANO NO MOTORIZADO)·2024-09-01DGAC Chile
A Cessna 172N struck electrical cables while on final approach to land at Aucó Aerodrome in Chile. The pilot was uninjured, but the aircraft sustained damage…
A Bombardier DHC-8-402 suffered a tail strike during landing at Puerto Williams on September 9, 2024. All 76 occupants were unharmed, but the aircraft…
A MYD JS-MD 3 glider veered off the runway and struck a wall at Vitacura Aerodrome on January 6, 2025. The pilot was uninjured, but the aircraft sustained…
A recreational paraglider flight in Puchuncaví, Chile, ended with the pilot sustaining serious injuries after a rapid descent and impact with a hillside on…
PARAPENTE (ULTRALIVIANO NO MOTORIZADO)·2025-03-29DGAC Chile
A Tecnam P2006T landed on its belly at an aerodrome in Poland after the crew failed to confirm landing gear deployment. The incident resulted in no injuries…
