MD11 flight crew receives a level 1 alert air system 2 off followed by a level 3 alert air manf 2 fa...

Narrative:

25 minutes into flight a level 1 air system 2 off (air system 2) came up. As I was pulling out the QRH a level 3 air manf 2 (air manifold 2 fail) fail came up. The air system protected itself and did the automatic decay check. We followed QRH procedures which requires us to land at nearest suitable airport. I sent a message to dispatch with our emergency and said that we were going to return to the departure airport. We started to slow up and declared an emergency with ATC and requested to return. They put us on a vector and gave us new routing instructions. We also needed to dump 27K of fuel to land below max landing weight. ATC gave us approval to start dumping fuel as we were descending from FL255 to FL170. We request one turn in holding to complete the dump and to finish checklist. I briefed a CAT 1 auto land. After one turn in holding we were cleared inbound to an uneventful landing. The AC system operated as designed when the jet pump hose broke and was sending hot air into the AC. It was due to the failure of a part which is not readily accessible to inspect.

Original NASA ASRS Text

Title: MD11 flight crew receives a Level 1 alert AIR SYS 2 OFF followed by a Level 3 alert AIR MANF 2 FAIL shortly after level off in cruise. An emergency is declared; fuel is dumped and the flight returns to the departure airport.

Narrative: 25 minutes into flight a level 1 AIR SYS 2 OFF (Air System 2) came up. As I was pulling out the QRH a level 3 AIR MANF 2 (air manifold 2 fail) FAIL came up. The air system protected itself and did the automatic decay check. We followed QRH procedures which requires us to LAND AT NEAREST SUITABLE AIRPORT. I sent a message to Dispatch with our emergency and said that we were going to return to the departure airport. We started to slow up and declared an emergency with ATC and requested to return. They put us on a vector and gave us new routing instructions. We also needed to dump 27K of fuel to land below max landing weight. ATC gave us approval to start dumping fuel as we were descending from FL255 to FL170. We request one turn in holding to complete the dump and to finish checklist. I briefed a CAT 1 auto land. After one turn in holding we were cleared inbound to an uneventful landing. The AC system operated as designed when the jet pump hose broke and was sending hot air into the AC. It was due to the failure of a part which is not readily accessible to inspect.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1234497
Time
Date	201501
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZZ.ARTCC
State Reference	FO
Environment
Flight Conditions	IMC
Aircraft 1
Make Model Name	MD-11
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Pneumatic Ducting
Person 1
Function	Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe

MD11 flight crew receives a level 1 alert air system 2 off followed by a level 3 alert air manf 2 fail shortly after level off in cruise. An emergency is declared; fuel is dumped and the flight returns to the departure airport.