Medium large transport has engine vibrations at takeoff. Return land.

Attributes
ACN	252985
Time
Date	199309
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : tpa
State Reference	FL
Altitude	msl bound lower : 0 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tower : tpa tracon : cle
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	climbout : takeoff climbout : initial
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 120 flight time total : 12000 flight time type : 3000
ASRS Report	252985
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa other other : unspecified
Resolutory Action	other
Consequence	other Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

On takeoff roll approximately 100 KTS, both pilots felt a vibration. All engine indicators normal. Continued takeoff and climb out. Check with flight attendant revealed vibration felt also in forward cabin. At 11000 ft disconnected automatic throttles and retarded thrust. Noticeable vibration change with #2 throttle reduced. Requested return tpa. Normal landing, no emergency. Post-flight by maintenance showed fan blade damage and evidence of a bird strike. 6 fan blades appeared damaged. Flight cancelled.

Original NASA ASRS Text

Title: MLG HAS ENG VIBRATIONS AT TKOF. RETURN LAND.

Narrative: ON TKOF ROLL APPROX 100 KTS, BOTH PLTS FELT A VIBRATION. ALL ENG INDICATORS NORMAL. CONTINUED TKOF AND CLBOUT. CHK WITH FLT ATTENDANT REVEALED VIBRATION FELT ALSO IN FORWARD CABIN. AT 11000 FT DISCONNECTED AUTO THROTTLES AND RETARDED THRUST. NOTICEABLE VIBRATION CHANGE WITH #2 THROTTLE REDUCED. REQUESTED RETURN TPA. NORMAL LNDG, NO EMER. POST-FLT BY MAINT SHOWED FAN BLADE DAMAGE AND EVIDENCE OF A BIRD STRIKE. 6 FAN BLADES APPEARED DAMAGED. FLT CANCELLED.

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.