Dispatcher discusses the events surrounding a dual bleed trip and emergency descent to FL250. With b...

Narrative:

Flight requested voice contact. Voice contact was established between me and the crew. The captain stated that the left bleed had tripped and while attempting to reset; the right bleed tripped and they had accomplished an emergency descent to FL250. During descent right bleed reset. Fob was 16.2 and estimated arrival fuel was 4.8. I reviewed the QRH and confirmed with the captain that the cabin pressure was normal. I stated to the captain that plan would be to change destination to ZZZ and have maintenance defer left bleed engine shutoff valve and refuel to accommodate FL250 to destination; but before changing destination it was agreed to climb to FL300. During climb left tripped again. Destination was changed to ZZZ at that time. The QRH does not give guidance if climbing is permitted after descent is implemented and both right and left bleed reset and pressurization is normal. It only refers to MEL requirements for dispatching. I would like to see more clarification in the QRH.

Original NASA ASRS Text

Title: Dispatcher discusses the events surrounding a dual bleed trip and emergency descent to FL250. With both bleeds reset a second attempt was made to reach cruise altitude with similar results. Crew and Dispatcher agree to divert for fuel and maintenance.

Narrative: Flight requested voice contact. Voice contact was established between me and the crew. The Captain stated that the left bleed had tripped and while attempting to reset; the right bleed tripped and they had accomplished an emergency descent to FL250. During descent right bleed reset. FOB was 16.2 and estimated arrival fuel was 4.8. I reviewed the QRH and confirmed with the Captain that the cabin pressure was normal. I stated to the Captain that plan would be to change destination to ZZZ and have Maintenance defer left bleed engine shutoff valve and refuel to accommodate FL250 to destination; but before changing destination it was agreed to climb to FL300. During climb left tripped again. Destination was changed to ZZZ at that time. The QRH does not give guidance if climbing is permitted after descent is implemented and both right and left bleed reset and pressurization is normal. It only refers to MEL requirements for dispatching. I would like to see more clarification in the QRH.

Data retrieved from NASA's ASRS site as of April 2012 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	915429
Time
Date	201010
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Component
Aircraft Component	Pneumatic Valve/Bleed Valve
Person 1
Function	Dispatcher
Events
Anomaly	Aircraft Equipment Problem Critical

Dispatcher discusses the events surrounding a dual bleed trip and emergency descent to FL250. With both bleeds reset a second attempt was made to reach cruise altitude with similar results. Crew and dispatcher agree to divert for fuel and maintenance.