A CL65 rj is mandated to return land when an unidented buzzing occurs after takeoff from cvg, oh.

Attributes
ACN	462270
Time
Date	199912
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : cvg.airport
State Reference	OH
Altitude	agl single value : 1000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : cvg.tracon
Operator	common carrier : air carrier
Make Model Name	Regional Jet CL65, Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Route In Use	departure : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : instrument pilot : multi engine pilot : commercial
Experience	flight time last 90 days : 240 flight time total : 3200 flight time type : 700
ASRS Report	462270
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe maintenance problem : improper maintenance non adherence : company policies non adherence : published procedure other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : diverted to another airport other
Consequence	other
Factors
Maintenance	contributing factor : schedule pressure performance deficiency : inspection performance deficiency : unqualified personnel
Supplementary
Problem Areas	Maintenance Human Performance Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

I arrived at aircraft to conduct flight from cvg to lan. Maintenance svced the crew oxygen system (filled oxygen). After their completion and prior to departure I conducted and completed the preflight inspection of the aircraft. Shortly after a normal takeoff we noticed a buzzing sound growing louder as the aircraft climbed out. We leveled the aircraft and notified ATC that we needed to return for landing. During the turn to final approximately 7 NM southwest of the airport, the noise suddenly stopped. No indications in the cockpit at any time showed anything but normal. After a normal landing, we returned to the gate. Maintenance met the aircraft to check the aircraft. They discovered the oxygen service door was fully open, and then secured it. The aircraft returned to service immediately following maintenance's inspection.

Original NASA ASRS Text

Title: A CL65 RJ IS MANDATED TO RETURN LAND WHEN AN UNIDENTED BUZZING OCCURS AFTER TKOF FROM CVG, OH.

Narrative: I ARRIVED AT ACFT TO CONDUCT FLT FROM CVG TO LAN. MAINT SVCED THE CREW OXYGEN SYS (FILLED OXYGEN). AFTER THEIR COMPLETION AND PRIOR TO DEP I CONDUCTED AND COMPLETED THE PREFLT INSPECTION OF THE ACFT. SHORTLY AFTER A NORMAL TKOF WE NOTICED A BUZZING SOUND GROWING LOUDER AS THE ACFT CLBED OUT. WE LEVELED THE ACFT AND NOTIFIED ATC THAT WE NEEDED TO RETURN FOR LNDG. DURING THE TURN TO FINAL APPROX 7 NM SW OF THE ARPT, THE NOISE SUDDENLY STOPPED. NO INDICATIONS IN THE COCKPIT AT ANY TIME SHOWED ANYTHING BUT NORMAL. AFTER A NORMAL LNDG, WE RETURNED TO THE GATE. MAINT MET THE ACFT TO CHK THE ACFT. THEY DISCOVERED THE OXYGEN SVC DOOR WAS FULLY OPEN, AND THEN SECURED IT. THE ACFT RETURNED TO SVC IMMEDIATELY FOLLOWING MAINT'S INSPECTION.

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.