Date: 201206
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb; Initial Climb
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Generator Drive
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Human factors: Workload; Training / Qualification; Time Pressure; Situational Awareness; Distraction
Second reporter function: Pilot Not Flying; Captain
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Passenger; Person Flight Attendant; Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Returned To Departure Airport; General Maintenance Action; General Release Refused / Aircraft Not Accepted; General Declared Emergency
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Took off and assigned 180 heading immediately after switching to departure. Noticed the steady rumble at the controls also immediately after clean up. Commented to the Captain that something was wrong when we got a Master Caution and Generator OFF Light on left engine. Cabin chimed about that time to say passengers thought spoilers were up on left side. I took the radios and continued to fly and informed ATC that we were declaring an emergency and requested level off at next altitude coming up which was 11;000. I started the APU and asked for vectors back around to land at the departure airport. The descent and configuring for landing were still controllable though the rumble continued. The engine; other than the generator; operated normally. The landing was normal at flaps 30 with auto brakes 2. Weather was CAVU and wind 260/4. The cowling departed the aircraft on landing; and I assume when I went into reverse. It was retrieved on the runway. No leaks or other damage was noted by fire trucks so we taxied back to the gate. Lost cowling to left engine which also cut generator for that engine.


Second narrative: After takeoff and during climb out there was a distinct vibration though the aircraft. Left generator fell off line. Flight attendants called stating that there was a metal object standing up at the left engine. Upon executing the QRH procedures for the Generator OFF Light I was able to get the generator to come back on line. We declared an emergency and landed back at the departure airport. Post inspection found out that the left engine outboard cowling was ripped off the engine. Airport personnel found the cowling on the departure runway which we had landed on. Aircraft was taken out of service.

Second callback: The Reporter stated that an access panel on the upper left side of the left engine cowl was apparently not latched or the latch failed on takeoff. The result was that the panel was sticking up and appeared to a passenger to be part of the wing. After the panel unlatched it cut the left generator white feeder lines inside the cowling which tripped the generator OFF. The Reporter stated that the wires at top of area inside the access area were black where the panel sliced into them. The generator did reset and remained on line. During landing the panel metal tore and separated leaving only a small portion of it at the connecting fixture point.

Synopsis: After takeoff B737-800 passengers reported a spoiler up and the Generator OFF light alerted so an emergency was declared and the flight returned to the departure airport where a left engine access panel was discovered missing.