<< >> NASA ASRS Report 341381, July 1996

An air carrier medium large transport flew unpressurized bos-bwi because the crew could not get the pressurization system to work. Aircraft equipment problem pressurization system.

Attributes
ACN	341381
Time
Date	199607
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : bos
State Reference	MA
Altitude	agl bound lower : 0 agl bound upper : 8000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bos tower : fay
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude cruise other ground other : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	341381
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

During taxi, captain shut down the left pack due to an unrelated problem. Left pack switch was off, isolation valve was closed. Right bleed switch was on. After takeoff, aircraft would not pressurize. Climb rate was slowed and aircraft leveled off at 8000 ft MSL. Pressurization could not be restored in automatic, standby, or manual modes. It was noted that the outflow valve was closed and right duct pressure was 30 psi, yet cabin climbed and descended with the aircraft. A check for air leaks or structural damage was accomplished. None were noted. Captain elected to continue unpressurized at 10000 ft to bwi. FMC determined en route and reserve fuel to be within limits.

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Original NASA ASRS Text

Title: AN ACR MLG FLEW UNPRESSURIZED BOS-BWI BECAUSE THE CREW COULD NOT GET THE PRESSURIZATION SYS TO WORK. ACFT EQUIP PROB PRESSURIZATION SYS.

Narrative: DURING TAXI, CAPT SHUT DOWN THE L PACK DUE TO AN UNRELATED PROB. L PACK SWITCH WAS OFF, ISOLATION VALVE WAS CLOSED. R BLEED SWITCH WAS ON. AFTER TKOF, ACFT WOULD NOT PRESSURIZE. CLB RATE WAS SLOWED AND ACFT LEVELED OFF AT 8000 FT MSL. PRESSURIZATION COULD NOT BE RESTORED IN AUTO, STANDBY, OR MANUAL MODES. IT WAS NOTED THAT THE OUTFLOW VALVE WAS CLOSED AND R DUCT PRESSURE WAS 30 PSI, YET CABIN CLBED AND DSNDED WITH THE ACFT. A CHK FOR AIR LEAKS OR STRUCTURAL DAMAGE WAS ACCOMPLISHED. NONE WERE NOTED. CAPT ELECTED TO CONTINUE UNPRESSURIZED AT 10000 FT TO BWI. FMC DETERMINED ENRTE AND RESERVE FUEL TO BE WITHIN LIMITS.

Data retrieved from NASA's ASRS site as of July 2007 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.