<< >> NASA ASRS Report 1106716, August 2013

Upon experiencing excessive vibration from the number 4 engine shortly after takeoff; a B747 flight crew declared an emergency; shut down the engine; dumped fuel to max landing weight and returned safely to their departure airport.

Attributes
ACN	1106716
Time
Date	201308
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	B747 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Takeoff
Flight Plan	IFR
Component
Aircraft Component	Turbine Engine
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 90 Flight Crew Total 22000 Flight Crew Type 110
Person 2
Function	First Officer Pilot Not Flying
Events
Anomaly	Aircraft Equipment Problem Critical Inflight Event / Encounter Bird / Animal

Narrative:

After liftoff we felt a strong vibration from the number 4 engine. The N1 vibration indicated above 5. At approximately 2;000 ft we retarded engine per the QRH. Vibration went away but continued once throttle moved above 70% N1. We left number 4 engine retarded and climbed to FL220 where with concurrence from dispatch and maintenance control declared an emergency; dumped fuel and returned to our departure airport. After a normal landing and gate return; maintenance advised us that there was a bird strike on the number 4 engine.

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Original NASA ASRS Text

Title: Upon experiencing excessive vibration from the Number 4 Engine shortly after takeoff; a B747 flight crew declared an emergency; shut down the engine; dumped fuel to max landing weight and returned safely to their departure airport.

Narrative: After liftoff we felt a strong vibration from the Number 4 Engine. The N1 vibration indicated above 5. At approximately 2;000 FT we retarded engine per the QRH. Vibration went away but continued once throttle moved above 70% N1. We left Number 4 Engine retarded and climbed to FL220 where with concurrence from Dispatch and Maintenance Control declared an emergency; dumped fuel and returned to our departure airport. After a normal landing and gate return; Maintenance advised us that there was a bird strike on the Number 4 engine.

Data retrieved from NASA's ASRS site as of July 2013 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.