Narrative:

Departing mdt during normal takeoff procedures, crew selected landing gear to retraction. Landing gear and gear doors both showed normal up and locked indications, however, a loud pulsating noise was heard coming from the left side of the nose. A vibration could also be felt throughout the aircraft. Company maintenance was called and the gear was cycled numerous times, each time producing the same effect. Upon gear extension, the noise would stop, but each time the gear was retracted the noise/vibration would return. Flight crew elected and maintenance concurred that a diversion to the departure airport was necessary. Passenger were notified, coordination with the cabin crew was made and vectors from ATC were requested. An emergency was declared and normal checklists were completed with the aircraft returning to harrisburg, PA, without further incident.

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Original NASA ASRS Text

Title: FLC OF A CANADAIR CL604 REGIONAL JET DECLARED AN EMER AND RETURNED TO LAND AFTER EXPERIENCING AN ODD NOISE AND ACFT VIBRATION AFTER RETRACTING THE LNDG GEAR AFTER TKOF.

Narrative: DEPARTING MDT DURING NORMAL TKOF PROCS, CREW SELECTED LNDG GEAR TO RETRACTION. LNDG GEAR AND GEAR DOORS BOTH SHOWED NORMAL UP AND LOCKED INDICATIONS, HOWEVER, A LOUD PULSATING NOISE WAS HEARD COMING FROM THE L SIDE OF THE NOSE. A VIBRATION COULD ALSO BE FELT THROUGHOUT THE ACFT. COMPANY MAINT WAS CALLED AND THE GEAR WAS CYCLED NUMEROUS TIMES, EACH TIME PRODUCING THE SAME EFFECT. UPON GEAR EXTENSION, THE NOISE WOULD STOP, BUT EACH TIME THE GEAR WAS RETRACTED THE NOISE/VIBRATION WOULD RETURN. FLC ELECTED AND MAINT CONCURRED THAT A DIVERSION TO THE DEP ARPT WAS NECESSARY. PAX WERE NOTIFIED, COORD WITH THE CABIN CREW WAS MADE AND VECTORS FROM ATC WERE REQUESTED. AN EMER WAS DECLARED AND NORMAL CHKLISTS WERE COMPLETED WITH THE ACFT RETURNING TO HARRISBURG, PA, WITHOUT FURTHER INCIDENT.

Data retrieved from NASA's ASRS site as of July 2007 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.