B767 crew had an aircraft parking brake that would not stay set.

Attributes
ACN	552582
Time
Date	200207
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : ord.airport
State Reference	IL
Altitude	agl single value : 0
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B767 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	ground : parked
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time type : 272
ASRS Report	552582
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical other anomaly other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : regained aircraft control other
Consequence	other other other Other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

Aircraft was stopped at gate, parking brake set, seatbelt sign turned off and parking flows initiated (hydraulic pumps off, etc). Looked out and noticed aircraft was moving and parking brake had released. Reapplied brakes causing aircraft to hold as it stopped. No passenger that were standing, waiting for jetway were injured. 1 flight attendant hit hand on galley but continued with her next flight. Aircraft was still in normal position for jetway and no one on ground was injured. First officer and I both noted parking brake was set, light was on, and we had parking brake EICAS message prior to its release. This was the second time brake released on its own. The first time was holding short of runway 30 at iad. In this occurrence after setting brake and removing hand from lever after approximately 10 seconds the brake released and had to be reset. There was good communications and heads up in both cases to prevent a more serious situation. The aircraft was written up for the brake release problem.

Original NASA ASRS Text

Title: B767 CREW HAD AN ACFT PARKING BRAKE THAT WOULD NOT STAY SET.

Narrative: ACFT WAS STOPPED AT GATE, PARKING BRAKE SET, SEATBELT SIGN TURNED OFF AND PARKING FLOWS INITIATED (HYD PUMPS OFF, ETC). LOOKED OUT AND NOTICED ACFT WAS MOVING AND PARKING BRAKE HAD RELEASED. REAPPLIED BRAKES CAUSING ACFT TO HOLD AS IT STOPPED. NO PAX THAT WERE STANDING, WAITING FOR JETWAY WERE INJURED. 1 FLT ATTENDANT HIT HAND ON GALLEY BUT CONTINUED WITH HER NEXT FLT. ACFT WAS STILL IN NORMAL POS FOR JETWAY AND NO ONE ON GND WAS INJURED. FO AND I BOTH NOTED PARKING BRAKE WAS SET, LIGHT WAS ON, AND WE HAD PARKING BRAKE EICAS MESSAGE PRIOR TO ITS RELEASE. THIS WAS THE SECOND TIME BRAKE RELEASED ON ITS OWN. THE FIRST TIME WAS HOLDING SHORT OF RWY 30 AT IAD. IN THIS OCCURRENCE AFTER SETTING BRAKE AND REMOVING HAND FROM LEVER AFTER APPROX 10 SECONDS THE BRAKE RELEASED AND HAD TO BE RESET. THERE WAS GOOD COMS AND HEADS UP IN BOTH CASES TO PREVENT A MORE SERIOUS SIT. THE ACFT WAS WRITTEN UP FOR THE BRAKE RELEASE PROB.

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.