B737-400
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Air Traffic Control Provided Assistance; Flight Crew Returned To Departure Airport; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Landed in Emergency Condition; General Declared Emergency
Aircraft
On takeoff roll; amber master caution light illuminated from an unknown source. Takeoff continued. At liftoff the number 1 transfer bus open light illuminated. Transfer bus was opening and closing rapidly; causing multiple primary instrument and navigation mode failures. Advised ATC and leveled off at 6;000 FT. Identified the light in the QRH and ran appropriate QRH checklist. Problem momentarily stopped and went into holding to burn off fuel to prevent an overweight landing. At that time the problem reoccurred with the bus continually cycling on and off; causing additional flight instrument and navigation failures. Elected to declare an emergency at that time and returned to the field; making an uneventful overweight landing. Upon landing the emergency was terminated; and taxied to the gate.
During takeoff; aircraft experienced an electrical malfunction; declared an emergency; and returned to land.