Narrative:

I did a walk-around and did not notice anything unusual. We taxied out and took off runway 23. After selecting gear up we noticed left main door amber light illuminated; nose door amber light illuminated and right main gear unsafe light illuminated and we heard a very loud grinding noise. We continued the climbout and finished the after takeoff checklist. After discussing the abnormal takeoff; we decided to execute an alternate gear extension and return to the airport. We notified ATC of our return plan.after flipping guarded switch up (I neglected to flip the inhibit switch to inhibit); I selected gear handle down and the gear came down; 3 green. Grinding noise halted. After a moment of confusion; I realized I had neglected to flip the switch to inhibit. I do understand how the inhibit switch works but made an error. We ran all of the appropriate checklists and landed with no issues. We did not declare an emergency and the landing was uneventful. We were issued a ferry permit to ferry the aircraft on; which we did.apparently; following replacement of the tire on the right main; the nacelle stored pump handle had been inadvertently left in the pump socket after a maintenance event. In conclusion; I believe I will in the future open the gear doors on every walk around even though it's not currently required on a normal crew swap without maintenance action. This was not an originating aircraft for this crew; nor did it follow maintenance that would have had me open the gear doors and check; but it could have been averted had all the doors been opened and the nacelles fully checked.

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Original NASA ASRS Text

Title: A DHC-8 flight crew experienced a landing gear retraction anomaly on takeoff. They performed a slightly flawed alternate gear extension procedure and returned to their departure airport.

Narrative: I did a walk-around and did not notice anything unusual. We taxied out and took off Runway 23. After selecting gear up we noticed Left Main Door amber light illuminated; Nose Door amber light illuminated and Right Main gear unsafe light illuminated and we heard a very loud grinding noise. We continued the climbout and finished the after takeoff checklist. After discussing the abnormal takeoff; we decided to execute an alternate gear extension and return to the airport. We notified ATC of our return plan.After flipping guarded switch up (I neglected to flip the inhibit switch to inhibit); I selected gear handle down and the gear came down; 3 green. Grinding noise halted. After a moment of confusion; I realized I had neglected to flip the switch to inhibit. I do understand how the inhibit switch works but made an error. We ran all of the appropriate checklists and landed with no issues. We did not declare an emergency and the landing was uneventful. We were issued a ferry permit to ferry the aircraft on; which we did.Apparently; following replacement of the tire on the right main; the nacelle stored pump handle had been inadvertently left in the pump socket after a maintenance event. In conclusion; I believe I will in the future open the gear doors on every walk around even though it's not currently required on a normal crew swap without maintenance action. This was not an originating aircraft for this crew; nor did it follow maintenance that would have had me open the gear doors and check; but it could have been averted had all the doors been opened and the nacelles fully checked.

Data retrieved from NASA's ASRS site as of April 2012 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.