gkainz
Final Approach
We've been chasing down an in-flight gear unsafe light in our new to us '97 Saratoga and have finally found the cause ... for anyone interested. I wish I had pictures, but I wasn't involved in the maintenance action that discovered the root cause of the problem.
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"We found the reason for the gear unsafe light. That is the only good news.
The Nose Gear Actuator is a hydraulic cylinder that pulls the nose gear up, and pushes it down during normal ops.
It is supposed to be securely fastened to the airframe so that it can pull and push. Four primary, large rivets do that, but... three of them have been sheared. The remaining one has allowed up/down operation, but without the others in line, that one becomes a pivot point during retraction, and rest of the associated anchor plate slides inward.
There is a fourth microswitch which should be activated when the gear is up. The motion described above moves the contactor so that it cannot operate the switch. So: the light was right. The gear was unsafe, but not in the way we all imagined. It was indeed up and in a safe position. Some number of cycles from now, someone would have experienced a failure of the nose gear to retract, which would mean it could not extend to the down-lock either. Or, if it failed during “gear down”, it would not have locked down."
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"We found the reason for the gear unsafe light. That is the only good news.
The Nose Gear Actuator is a hydraulic cylinder that pulls the nose gear up, and pushes it down during normal ops.
It is supposed to be securely fastened to the airframe so that it can pull and push. Four primary, large rivets do that, but... three of them have been sheared. The remaining one has allowed up/down operation, but without the others in line, that one becomes a pivot point during retraction, and rest of the associated anchor plate slides inward.
There is a fourth microswitch which should be activated when the gear is up. The motion described above moves the contactor so that it cannot operate the switch. So: the light was right. The gear was unsafe, but not in the way we all imagined. It was indeed up and in a safe position. Some number of cycles from now, someone would have experienced a failure of the nose gear to retract, which would mean it could not extend to the down-lock either. Or, if it failed during “gear down”, it would not have locked down."
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