Date: 201702
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Night
Aircraft: MD-11
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Climb
Airspace: Class E ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Engine Air Pneumatic Ducting
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Second reporter function: Pilot Flying; First Officer
Anomaly: Aircraft Equipment Problem Critical; Deviation - Speed All Types; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: On climbout through 16000 feet; approximately 7 minutes after takeoff; APU Fire Alert and APU Fire Handle Light illuminated; along with Aural Alert. Captain was Pilot Monitoring and FO was PF at time. PM assessed for a moment and conferred with PF before executing Phase One procedure. Level 3 Alert and Aural Alert went away after a few seconds but light in APU Fire Handle remained lit. Phase one procedure was complied with and Bottle 2 was discharged. In the meantime PM advised Center and coordinated immediate return. PM then ran QRH checklist for APU Fire while PF flew and talked to Center. After approximately one to two minutes after initially pulling fire handle and discharging the first bottle the Aural Alert and Level 3 Alert returned and the second bottle (Agent One) was discharged. Those two alerts returned intermittently throughout remainder of flight. Captain then took controls as PF and made the decision to stay fast (350 kts) below 10;000 to expedite return. PF slowed the airplane approaching and configured for landing on schedule. We intercepted the ILS on a visual approach becoming stable with checklists complete by 1000 AGL. Landing was normal and on rollout we coordinated with tower to exit onto the taxiway where emergency vehicles met the airplane to inspect the tail area for indications of fire/smoke. The emergency vehicles reported no abnormal visual or infrared indications. The fire handle remained illuminated but all other alerts stayed extinguished. We elected to taxi back to the gate with the emergency vehicles following us; continuing to monitor the airplane. During the taxi back the FO suggested we secure Engine 2. This seemed prudent given the likelihood of a bleed leak in the tail giving the Fire alerts so we secured Engine 2 and advised Ramp Tower. About two minutes after shutting down Engine 2 the light in the APU Fire Handle extinguished as well. We parked the aircraft and shut down normally. Log entries were made for the APU Fire alert and for a Reverser 2 Press Fault and Reverser 2 Unlock indication. Maintenance was debriefed on everything before leaving the airplane. FO did an outstanding job as both PF and PM throughout the emergency and made excellent and timely suggestions (securing number 2 engine on deck especially). In our debrief we discussed Captain's decision to momentarily delay executing Phase One procedure and agreed that it would have been better to immediately pull the APU Fire Handle and discharge the first bottle.APU Fire Indication; likely caused by Bleed Air leak in tail section. This was agreed with by maintenance who will make the actual determination of the cause. Nothing we could have done to prevent the emergency and I believe our CRM and decision making were sound with the exception of momentarily delaying the execution of Phase One procedures. Given the indications of a possible fire in the tail section of the fuselage I believe it was more than prudent to get the airplane on the ground ASAP and to exceed 250 kts below 10000.


Second narrative: [Report narrative contained no additional information.]


Synopsis: MD-11 flight crew reported experiencing an APU fire warning on climbout.