Large transport has brake cylinder fail during preflight pressurization of hydraulic system.

Attributes
ACN	271106
Time
Date	199405
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : mggt
State Reference	FO
Altitude	agl bound lower : 0 agl bound upper : 0
Aircraft 1
Controlling Facilities	artcc : zse
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	ground : preflight
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : flight engineer pilot : atp pilot : commercial
Experience	flight time last 90 days : 150 flight time total : 18000 flight time type : 1200
ASRS Report	271106
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

#2 brake cylinder failed as evidenced by a large stream of brake fluid coming out of brake system. This occurred when first officer pressurized the hydraulic system for a flight control check. Procedures call for the hydraulic to be pressurized after the exterior walk around, which he in fact accomplished noting no leaks. I also spoke to the mechanic who towed the aircraft to the gate. He also stated he did not see any leaks. It is my feeling that all major system should be pressurized during exterior walk arounds to help detect any possible leaks.

Original NASA ASRS Text

Title: LGT HAS BRAKE CYLINDER FAIL DURING PREFLT PRESSURIZATION OF HYD SYS.

Narrative: #2 BRAKE CYLINDER FAILED AS EVIDENCED BY A LARGE STREAM OF BRAKE FLUID COMING OUT OF BRAKE SYS. THIS OCCURRED WHEN FO PRESSURIZED THE HYD SYS FOR A FLT CTL CHK. PROCS CALL FOR THE HYD TO BE PRESSURIZED AFTER THE EXTERIOR WALK AROUND, WHICH HE IN FACT ACCOMPLISHED NOTING NO LEAKS. I ALSO SPOKE TO THE MECH WHO TOWED THE ACFT TO THE GATE. HE ALSO STATED HE DID NOT SEE ANY LEAKS. IT IS MY FEELING THAT ALL MAJOR SYS SHOULD BE PRESSURIZED DURING EXTERIOR WALK AROUNDS TO HELP DETECT ANY POSSIBLE LEAKS.

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.