Narrative:

On the ground when #1 for takeoff; two aircraft behind us saw the right main squirting hydraulic fluid onto the tire. We checked hydraulic system level at this time and could not see any loss show up on the gauge. Later the gauge showed some loss of fluid. We stayed there with parking brake set. Called fire trucks out; and then asked safety equipment to check us out with their thermal imaging equipment. They said there was no excessive heat signature and no fire or smoke. So; we asked the safety equipment to follow us to the gate as a precaution. At the gate; the gear sprayed brake fluid for a few minutes until we turned the hydraulic pumps off. Mechanic said a bleed bolt was loose. He tightened bolt; replaced lost fluid (which was never completely depleted); signed off maintenance logbook and we were able to fly. That all took about 3 hours; then; we flew to our destination without further incident. Event occurred because there was no safety wire on the bolt in question. Maintenance said there was another bolt just like it that was loose and could have leaked too. I don't know if this bolt was designed by embraer to be safety wired; but it should have been wired so this leak could have been prevented. It is possible that bleed bolts from both gears could have leaked in flight and then we could have lost fluid from both system 1 and system 2 hydraulics.

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Original NASA ASRS Text

Title: An ERJ190 Captain holding short for takeoff was notified by aircraft behind his that hydraulic fluid was squirting on a brake. After returning to the gate; Maintenance found that a brake bleed valve was not safety wired and leaking.

Narrative: On the ground when #1 for takeoff; two aircraft behind us saw the right main squirting hydraulic fluid onto the tire. We checked hydraulic system level at this time and could not see any loss show up on the gauge. Later the gauge showed some loss of fluid. We stayed there with parking brake set. Called fire trucks out; and then asked safety equipment to check us out with their thermal imaging equipment. They said there was no excessive heat signature and no fire or smoke. So; we asked the safety equipment to follow us to the gate as a precaution. At the gate; the gear sprayed brake fluid for a few minutes until we turned the hydraulic pumps off. Mechanic said a bleed bolt was loose. He tightened bolt; replaced lost fluid (which was never completely depleted); signed off maintenance logbook and we were able to fly. That all took about 3 hours; then; we flew to our destination without further incident. Event occurred because there was no safety wire on the bolt in question. Maintenance said there was another bolt just like it that was loose and could have leaked too. I don't know if this bolt was designed by Embraer to be safety wired; but it should have been wired so this leak could have been prevented. It is possible that bleed bolts from both gears could have leaked in flight and then we could have lost fluid from both system 1 and system 2 hydraulics.

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.