An EMB145's pressurization control failed climbing through FL270 so the crew declared an emergency; ...

Narrative:

Flight departed normally under day VFR conditions with the captain flying the aircraft. Climbing through approximately 27;000 ft we noticed a rapid change in cabin pressure. We immediately noted that indicated climb rate on the EICAS display was changing rapidly with variations of positive 3;000 ft per minute to negative 3;000 ft per minute. The cabin altitude indication was simultaneously climbing; quickly passing 10;000 ft and triggering the associated master warning. We performed the memory item procedures for rapid cabin depressurization; followed by the QRH; and then aom 1. We simultaneously followed the procedures for emergency descent and declared an emergency with ATC. The captain spoke with the flight attendant while the first officer complied with all applicable checklists. At nearly 15;000 ft cabin altitude the passenger oxygen masks had not automatically deployed so I directed them to be provided manually. We leveled off at 10;000 ft and assumed control of the pressurization manually as described in the pressurization auto fail checklist. The cabin pressure would not stabilize; so we continued with the remainder of the procedure which ultimately directed us to dump the cabin. We landed at a diversionary airport approximately 15 minutes later with a landing weight over maximum structural landing weight. Our sink rate was approximately 100 ft per minute on touchdown. All passengers and crew deplaned normally via jet bridge.

Original NASA ASRS Text

Title: An EMB145's pressurization control failed climbing through FL270 so the crew declared an emergency; began an emergency descent; performed the emergency procedures including dropping the passenger masks at 15;000 FT and diverted to an enroute airport.

Narrative: Flight departed normally under day VFR conditions with the Captain flying the aircraft. Climbing through approximately 27;000 FT we noticed a rapid change in cabin pressure. We immediately noted that indicated climb rate on the EICAS display was changing rapidly with variations of positive 3;000 FT per minute to negative 3;000 FT per minute. The cabin altitude indication was simultaneously climbing; quickly passing 10;000 FT and triggering the associated master warning. We performed the memory item procedures for Rapid Cabin Depressurization; followed by the QRH; and then AOM 1. We simultaneously followed the procedures for Emergency Descent and declared an emergency with ATC. The Captain spoke with the Flight Attendant while the First Officer complied with all applicable checklists. At nearly 15;000 FT cabin altitude the passenger oxygen masks had not automatically deployed so I directed them to be provided manually. We leveled off at 10;000 FT and assumed control of the pressurization manually as described in the Pressurization Auto Fail checklist. The cabin pressure would not stabilize; so we continued with the remainder of the procedure which ultimately directed us to dump the cabin. We landed at a diversionary airport approximately 15 minutes later with a landing weight over maximum structural landing weight. Our sink rate was approximately 100 FT per minute on touchdown. All passengers and crew deplaned normally via jet bridge.

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	948105
Time
Date	201105
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	EMB ERJ 145 ER&LR
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Pressurization Control System
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Commercial
Events
Anomaly	Aircraft Equipment Problem Critical

An EMB145's pressurization control failed climbing through FL270 so the crew declared an emergency; began an emergency descent; performed the emergency procedures including dropping the passenger masks at 15;000 ft and diverted to an enroute airport.