Narrative:

The flight crew of a cessna 680 lost steering capabilities using the aircraft tiller after landing and reported the following discrepancy: 'after landing was unable to steer aircraft with tiller. Tiller stuck in neutral position. Steered aircraft with rudder; brake and differential thrust. After parking tiller moved freely but does not turn.' a maintenance crew was dispatched the following morning and determined that the left steering cable had snapped and any input to the steering tiller failed to correspond to nose gear steering. While in the area; the technician observed the right cable had just begun to show signs of broken strands in the area where the cable passes through the pressure bulkhead seals. Both cables and seal plate assemblies were ordered and replaced. Upon further records review; these cables were inspected earlier this year under the following: nose landing gear assembly detailed inspection. Additionally; a maintenance crew reported the following: nose wheel steering travels out of spec (left 4 degrees right 9 degrees with rudder pedals). Maintenance crews performed the following: adjusted nose wheel steering cables and installed turnbuckle safeties in accordance with CE680 maintenance manual. Adjusted nose wheel steer unit adjustment screws and tiller wheel aft adjustment screw in accordance with CE680 maintenance manual. It is only my opinion but I believe it was at this point the cable was failing hence the loose cable tensions. The correction of the problem by the technicians by tightening the cables only led to exacerbate the problem further leading to the breakage.it is also my belief that the inspection task duration needs to be brought back to a 600 hour event with specific instructions to examine the cable the entire length with specific emphasis on the area that passes through the bulkhead seals. It is these seals that appear to be the cause of the broken strands. When the new seals are installed the holes in the seal where the cable passes is smaller in diameter than the cable diameter is resulting in the cable being used to enlarge the seal hole as the cable passes back and forth when being exercised. Over time as one strand breaks causes the cable to displace a larger diameter thus causing more strands to break.

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Original NASA ASRS Text

Title: A Maintenance Inspector reported that a Cessna 680 lost steering capabilities due to a broken steering cable.

Narrative: The flight crew of a Cessna 680 lost steering capabilities using the aircraft tiller after landing and reported the following discrepancy: 'After landing was unable to steer aircraft with tiller. Tiller stuck in neutral position. Steered aircraft with rudder; brake and differential thrust. After parking tiller moved freely but does not turn.' A maintenance crew was dispatched the following morning and determined that the left steering cable had snapped and any input to the steering tiller failed to correspond to nose gear steering. While in the area; the Technician observed the right cable had just begun to show signs of broken strands in the area where the cable passes through the pressure bulkhead seals. Both cables and seal plate assemblies were ordered and replaced. Upon further records review; these cables were inspected earlier this year under the following: Nose Landing Gear Assembly Detailed Inspection. Additionally; a maintenance crew reported the following: Nose wheel steering travels out of spec (left 4 degrees right 9 degrees with rudder pedals). Maintenance crews performed the following: Adjusted nose wheel steering cables and installed turnbuckle safeties in accordance with CE680 maintenance manual. Adjusted nose wheel steer unit adjustment screws and tiller wheel aft adjustment screw in accordance with CE680 maintenance manual. It is only my opinion but I believe it was at this point the cable was failing hence the loose cable tensions. The correction of the problem by the technicians by tightening the cables only led to exacerbate the problem further leading to the breakage.It is also my belief that the inspection task duration needs to be brought back to a 600 hour event with specific instructions to examine the cable the entire length with specific emphasis on the area that passes through the bulkhead seals. It is these seals that appear to be the cause of the broken strands. When the new seals are installed the holes in the seal where the cable passes is smaller in diameter than the cable diameter is resulting in the cable being used to enlarge the seal hole as the cable passes back and forth when being exercised. Over time as one strand breaks causes the cable to displace a larger diameter thus causing more strands to break.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.