Critical Investigation of Aircraft Rigging Deviations Impacting Elevator Control Systems
This report by Robert L. Swaim, National Resource Specialist in Aircraft Systems Engineering, details significant deviations observed during ground tests related to aircraft elevator rigging. Key findings include the incorrect installation of the aft rig pin and its implications on elevator control cable handling. The report references the Colgan Air Flight 9446 accident to highlight the critical nature of functional inspections for maintenance. Through careful analysis of rig pin placement, cable tensions, and operational safety, this document emphasizes the necessity of adhering to strict aviation maintenance protocols.
Critical Investigation of Aircraft Rigging Deviations Impacting Elevator Control Systems
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Presentation Transcript
Robert L. Swaim National Resource Specialist Aircraft Systems Engineering
Aft Rig Pin Installed in Ground Tests(First AMM Deviation) Aft Rig Pin Hole
Forward Rig Pin May Miss Bellcrank(Second AMM Deviation) Control Yoke Rig Pin Hole In Floor Structure Rig Pin Hole In Bellcrank (View from aft) (View from forward)
Tighten Control Cables(Third AMM Deviation) 1. Aft rig pin installed Elevator-Down Cable 2. Forward rig pin missed bellcrank Elevator-Up Cable Elevator-Down Cable Elevator-Up Cable 3. Tighten elevator-up cable.
Tightening Elevator-Down CableMoved Forward Bellcrank Aft Side of Bellcrank Stopped At Improperly Installed Rig Pin. (Pin should be inserted in bellcrank hole.)
Cable Misrig Altered Relation Between FDR Sensor and Elevator Rig pin holds elevator In one position Elevator-Down Cable Turnbuckles alter overall cable lengths Elevator-Up Cable FDR senses shift in column position
Colgan Accident (Similar airplane) CommutAir Incident (Similar airplane)
Functional Inspections Should Be Required for Critical Maintenance
Robert L. Swaim National Resource Specialist Aircraft Systems Engineering
Pitch Trim Cable Drum Illustration Colgan Air Flight 9446 Investigation
Capt yoke full aft Capt yoke mid position Fwd bellcrank access Capt yoke full fwd
Pitch Control Turnbuckles Found In Wreckage 7.30 Inches Aircraft Nose Down (AND) 5.54 Inches Aircraft Nose Up (ANU)
