Date: 201508
Local time of day: 0601-1200
Location: LAS.Airport, NV
Light: Daylight
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
ATC / advisory: Tower LAS
Aircraft component: Pneumatic System
Component problem: Design; Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Fatigue
Anomaly: Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Illness / Injury
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate; In-flight
Result: Flight Crew Returned To Departure Airport; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Weather; Company Policy; Aircraft; Human Factors
Primary problem: Aircraft

Narrative: My fatigue was a culmination of multiple factors. I had initially woken up at XA:30 PDT to catch my commute to LAS. I arrived at around XE:30 PDT; but my show time was not until XH:10. On the first flight we experienced a Tail Temp High annunciation on takeoff. As per the QRH; we shut down the APU and continued. The resulting maintenance on the ground resulted in a deferred APU. The temperature was in the high 80's/low 90's and the airplane was very hot inside. Complicating this was the fact that the station does not have an air conditioning cart. Also; during boarding; the stations GPU overheated and shut down; resulting in a power loss to the aircraft and halted the operation of the packs; which up until this point had been running off of air from the start cart. This resulted in a further delay and a hotter airplane. The airplane was hot enough that the flight attendants noted that the passengers were becoming unruly. The end solution was to wait until the stations GPU had cooled down; then quickly start one engine. This resulted in a further delay; and an even hotter airplane since we had to close the door and taxi away from the ramp to start the other engine. Upon reaching LAS; the captain and I tail swapped to a different airplane for our next turn. On this flight in the new plane; we also had a Tail Temp High annunciator on takeoff. This time the light did not turn off. As per the QRH we shut down the APU; and returned to LAS with the left engine at idle power. The lack of airflow from the left engine; the lack of APU; and the QRH-directed operation of the packs in 'HP bleed off;' resulted in a very hot cabin again. It was hot enough to give a passenger heat stroke; so we had the paramedics meet us at the gate.It was very apparent that after such a long day; early morning; delays; extreme heat; and multiple mechanical failures; I was not fit to fly another turn.Obviously weather cannot be controlled; and the nature of commuting makes days longer. But I believe that a long and complicated day could have been made shorter and easier by having appropriate and correctly operating equipment such as a GPU and air conditioning cart at the outstation; as well as a more thorough examination/maintenance program regarding our bleed air systems; could have prevented this. Two occurrences of the same problem to the same crew in two different airplanes on the same day is too much of a coincidence to ignore.




Synopsis: Air Carrier First Officer laments the inability of his aircraft's cooling system to function on very hot days and the lack of properly functioning ground equipment that will take its place. On this day; two different aircraft experience Tail Temp High annunciations requiring the APU to be shut down and ground equipment that cannot handle the task on the ground.