Narrative:

On may/tue/05; I was taxiing with a student in ZZZ1. As we approached the departure end of the runway; my student started to brake in anticipation of the left turn onto the runway. As she applied the brakes; the aircraft started turning to the right. I took control; applied full left rudder/brake and ensured that the power was idle. The aircraft continued turning to the right until it came to a full stop; perpendicular to the taxiway; but still on the paved surface. We shut the engine down and inspected the left brake system. There was no pressure in the brake pedal; and no apparent leaks in the brake lines. We manually turned the aircraft to face the proper direction; and decided to cancel the lesson and return to our home base in ZZZ2. The rest of the flight was uneventful. Upon our arrival; I notified the owner/operator that the left brake was inoperative. Since another student was scheduled to fly the same aircraft; he decided that we should fix the brakes as soon as possible. I was given a hydraulic fluid dispenser and instructed on how to fill the left master cylinder reservoir. I followed the instructions and filled the reservoir; but the brake pedal did not develop any pressure. I was then told that the brakes probably had air in the lines and needed to be bled. I was given a different pump; and was instructed on how to use the pump to bleed the brake line. I accomplished this task; and this solved the problem. The brake did have pressure and worked normally. In doing this work; I was under the impression that I was acting under my authority/authorized as pilot under 14 crash fire rescue equipment 43.3(G) and appendix a to part 43(C). The former states; 'the holder of a pilot certificate...may perform preventive maintenance on any aircraft owned or operated by that pilot...' while the latter lists 'replenishing hydraulic fluid in the hydraulic reservoir' as 'preventive maintenance.' what I didn't realize is that there is a difference between replenishing hydraulic fluid in the hydraulic reservoir; and bleeding the brake system. At the time; the difference to me was subtle: the reservoir being filled from the bottom rather than from the top. Bleeding brakes is not considered preventive maintenance; and must be performed by an authority/authorized mechanic. Additionally; I failed to record the maintenance that I performed in the aircraft's maintenance record; in accordance with 14 crash fire rescue equipment 43.9.

Related reports:

Google
 

Original NASA ASRS Text

Title: A C152 ON TAXI HAD THE L BRAKE FAIL. ACFT FLOWN TO HOME BASE WHERE INSTRUCTOR PLT SVCED BRAKE FLUID AND BLED BRAKE LINES. NO LOG ENTRY.

Narrative: ON MAY/TUE/05; I WAS TAXIING WITH A STUDENT IN ZZZ1. AS WE APCHED THE DEP END OF THE RWY; MY STUDENT STARTED TO BRAKE IN ANTICIPATION OF THE L TURN ONTO THE RWY. AS SHE APPLIED THE BRAKES; THE ACFT STARTED TURNING TO THE R. I TOOK CTL; APPLIED FULL L RUDDER/BRAKE AND ENSURED THAT THE PWR WAS IDLE. THE ACFT CONTINUED TURNING TO THE R UNTIL IT CAME TO A FULL STOP; PERPENDICULAR TO THE TXWY; BUT STILL ON THE PAVED SURFACE. WE SHUT THE ENG DOWN AND INSPECTED THE L BRAKE SYS. THERE WAS NO PRESSURE IN THE BRAKE PEDAL; AND NO APPARENT LEAKS IN THE BRAKE LINES. WE MANUALLY TURNED THE ACFT TO FACE THE PROPER DIRECTION; AND DECIDED TO CANCEL THE LESSON AND RETURN TO OUR HOME BASE IN ZZZ2. THE REST OF THE FLT WAS UNEVENTFUL. UPON OUR ARR; I NOTIFIED THE OWNER/OPERATOR THAT THE L BRAKE WAS INOP. SINCE ANOTHER STUDENT WAS SCHEDULED TO FLY THE SAME ACFT; HE DECIDED THAT WE SHOULD FIX THE BRAKES ASAP. I WAS GIVEN A HYD FLUID DISPENSER AND INSTRUCTED ON HOW TO FILL THE L MASTER CYLINDER RESERVOIR. I FOLLOWED THE INSTRUCTIONS AND FILLED THE RESERVOIR; BUT THE BRAKE PEDAL DID NOT DEVELOP ANY PRESSURE. I WAS THEN TOLD THAT THE BRAKES PROBABLY HAD AIR IN THE LINES AND NEEDED TO BE BLED. I WAS GIVEN A DIFFERENT PUMP; AND WAS INSTRUCTED ON HOW TO USE THE PUMP TO BLEED THE BRAKE LINE. I ACCOMPLISHED THIS TASK; AND THIS SOLVED THE PROB. THE BRAKE DID HAVE PRESSURE AND WORKED NORMALLY. IN DOING THIS WORK; I WAS UNDER THE IMPRESSION THAT I WAS ACTING UNDER MY AUTH AS PLT UNDER 14 CFR 43.3(G) AND APPENDIX A TO PART 43(C). THE FORMER STATES; 'THE HOLDER OF A PLT CERTIFICATE...MAY PERFORM PREVENTIVE MAINT ON ANY ACFT OWNED OR OPERATED BY THAT PLT...' WHILE THE LATTER LISTS 'REPLENISHING HYD FLUID IN THE HYD RESERVOIR' AS 'PREVENTIVE MAINT.' WHAT I DIDN'T REALIZE IS THAT THERE IS A DIFFERENCE BTWN REPLENISHING HYD FLUID IN THE HYD RESERVOIR; AND BLEEDING THE BRAKE SYS. AT THE TIME; THE DIFFERENCE TO ME WAS SUBTLE: THE RESERVOIR BEING FILLED FROM THE BOTTOM RATHER THAN FROM THE TOP. BLEEDING BRAKES IS NOT CONSIDERED PREVENTIVE MAINT; AND MUST BE PERFORMED BY AN AUTH MECH. ADDITIONALLY; I FAILED TO RECORD THE MAINT THAT I PERFORMED IN THE ACFT'S MAINT RECORD; IN ACCORDANCE WITH 14 CFR 43.9.

Data retrieved from NASA's ASRS site as of January 2009 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.