Date: 201208
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: Boeing Company Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Takeoff / Launch
Airspace: Class B ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Turbine Engine
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Critical
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Inflight Shutdown; Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Declared Emergency; General Maintenance Action
Contributing factors: Aircraft; Weather
Primary problem: Aircraft

Narrative: This was a through-flight; and the APU was allowed to run throughout the turn due to the very high ambient temperatures (44 C/110 F). First Officer observed what appeared to be a brief illumination of the engine fire detection fault light after engine start. Shortly after the start of our taxi we noticed the following: Engine 2 overheat light illuminated intermittently. The associated overheat detection switch appeared to be in the normal position; but when the Captain went to place his hand on it; the switch clicked into its' seated position (in the normal notch). The engine fire detection panel had been tested and checked earlier in the day. The abnormal switch position; in combination with the intermittent nature of the indication; and previous brief illumination of the fault light; lead us to believe that the overheat indication might have been related to the overheat detection switch not being fully seated in its normal position. All engine indications/condition appeared normal. We then referenced the QRH and the MEL; and after conferring with Maintenance Control performed a detector loop test per the MEL. The engine 2 overheat light was out while performing the test; but did not illuminate as a result of the test. Our conclusion was: no positive test in the normal position (no engine 2 overheat indication). The test was positive when selecting loop A only. This seemed to confirm that the problem had been the result of a loop malfunction; and was consistent with the MEL (O) instructions (ATA 26-02). The Captain coordinated with Maintenance Control via phone; and both offices concurred with our assessment of the situation and cleared us to continue with the flight. We complied with the provisions of the MEL and we continued. During the takeoff roll; at approximately 120 KTS; the Captain noticed that the #2 engine EGT was higher than the #1 by about 50 degrees; but still well within limits. Not sure if this was related to the event or not. Shortly after lift-off the engine #2 overheat light illuminated. This time the light came on steady. We declared an emergency and proceeded with the QRH procedures. This led to a #2 engine shutdown. Shortly after pulling the start lever to cutoff; the engine #2 overheat light extinguished. Performed a single engine landing and coordinated with emergency personnel on the ground before taxiing to the gate. We briefed an overweight landing; but we believe that landing weight was below the limit upon touchdown. Touchdown was smooth. Note: I found the iPad to be very helpful for reference during/after this event.




Synopsis: Air Carrier First Officer describes the circumstances leading up to an engine overheat warning shortly after takeoff on a very hot day. The engine is shut down and flight returns to departure airport.