Narrative:

A student and myself departed ZZZ on a routine training flight. The training maneuvers performed included normal stalls; cycling the landing gear; takeoff and lndgs; and taxiing for further departures. Upon returning to ZZZ and doing a pre-landing check; it was noted that the nitrogen that is used for braking was low. It was my opinion that if I raised the gear again to go to an alternate airport; the brake system would be further discharged. Note: each time the gear is cycled; the brakes are automatically applied to stop the rotation of the tires in the wheel wells. I determined that I have operated the plane at this level of nitrogen in the past and that it shouldn't be a problem. During the landing roll my student stated that he had no brakes. I then took the aircraft and applied the brakes and attempted to steer the aircraft with differential braking. There was minimal brake power and I realized that we may not be able to stop in the runway distance that we had remaining. I turned the aircraft to the right toward a rock embankment or hill. It was at this point that I commenced an emergency shutdown of the engine; shut off the fire cock valve and applied the emergency brakes. The aircraft; while slowing further; struck a VASI landing box on the north side of the runway causing minimal damage to the airplane equivalent to hangar rash. The VASI light system was completely destroyed; however. After passing over the VASI system; we crossed the north taxiway and rolled over the rock embankment. The aircraft came to a stop on the edge of the hill. We secured the aircraft and exited. After recovering the aircraft from the hill with the help from a local towing company; I determined that the damage was light and limited to the leading edge of the wing where it came into contact with the VASI box. By appearances; it looked as though I had struck a bird. There was no damage resulting from coming to rest on the embankment as the aircraft came to a stop from applying the emergency brakes. There was no further damage caused during the recovery of the aircraft. Later that evening; I cycled the landing gear on jacks and refilled the nitrogen brake system. After taxiing the aircraft to verify that with the brake system full; the brakes operated normally; I departed ZZZ to fly home without incident. Callback conversation with reporter revealed the following information: the reporter stated the aircraft incurred minor damage and the cause of the loss of braking was just plain running out of nitrogen. Each time the landing gear is retracted; the nitrogen pressure stops the rotating wheels and slightly depletes the limited nitrogen supply. The nitrogen bottle pressure was checked on the preflight check and appeared adequate for the flight.

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Original NASA ASRS Text

Title: AN AERO L-29 ON LNDG EXPERIENCED A LOSS OF BRAKING; STRIKING A VASI LNDG BOX AND DEPARTING THE RWY ROLLING OVER A ROCK EMBANKMENT.

Narrative: A STUDENT AND MYSELF DEPARTED ZZZ ON A ROUTINE TRAINING FLT. THE TRAINING MANEUVERS PERFORMED INCLUDED NORMAL STALLS; CYCLING THE LNDG GEAR; TKOF AND LNDGS; AND TAXIING FOR FURTHER DEPS. UPON RETURNING TO ZZZ AND DOING A PRE-LNDG CHK; IT WAS NOTED THAT THE NITROGEN THAT IS USED FOR BRAKING WAS LOW. IT WAS MY OPINION THAT IF I RAISED THE GEAR AGAIN TO GO TO AN ALTERNATE ARPT; THE BRAKE SYS WOULD BE FURTHER DISCHARGED. NOTE: EACH TIME THE GEAR IS CYCLED; THE BRAKES ARE AUTOMATICALLY APPLIED TO STOP THE ROTATION OF THE TIRES IN THE WHEEL WELLS. I DETERMINED THAT I HAVE OPERATED THE PLANE AT THIS LEVEL OF NITROGEN IN THE PAST AND THAT IT SHOULDN'T BE A PROB. DURING THE LNDG ROLL MY STUDENT STATED THAT HE HAD NO BRAKES. I THEN TOOK THE ACFT AND APPLIED THE BRAKES AND ATTEMPTED TO STEER THE ACFT WITH DIFFERENTIAL BRAKING. THERE WAS MINIMAL BRAKE PWR AND I REALIZED THAT WE MAY NOT BE ABLE TO STOP IN THE RWY DISTANCE THAT WE HAD REMAINING. I TURNED THE ACFT TO THE R TOWARD A ROCK EMBANKMENT OR HILL. IT WAS AT THIS POINT THAT I COMMENCED AN EMER SHUTDOWN OF THE ENG; SHUT OFF THE FIRE COCK VALVE AND APPLIED THE EMER BRAKES. THE ACFT; WHILE SLOWING FURTHER; STRUCK A VASI LNDG BOX ON THE N SIDE OF THE RWY CAUSING MINIMAL DAMAGE TO THE AIRPLANE EQUIVALENT TO HANGAR RASH. THE VASI LIGHT SYS WAS COMPLETELY DESTROYED; HOWEVER. AFTER PASSING OVER THE VASI SYS; WE CROSSED THE N TXWY AND ROLLED OVER THE ROCK EMBANKMENT. THE ACFT CAME TO A STOP ON THE EDGE OF THE HILL. WE SECURED THE ACFT AND EXITED. AFTER RECOVERING THE ACFT FROM THE HILL WITH THE HELP FROM A LCL TOWING COMPANY; I DETERMINED THAT THE DAMAGE WAS LIGHT AND LIMITED TO THE LEADING EDGE OF THE WING WHERE IT CAME INTO CONTACT WITH THE VASI BOX. BY APPEARANCES; IT LOOKED AS THOUGH I HAD STRUCK A BIRD. THERE WAS NO DAMAGE RESULTING FROM COMING TO REST ON THE EMBANKMENT AS THE ACFT CAME TO A STOP FROM APPLYING THE EMER BRAKES. THERE WAS NO FURTHER DAMAGE CAUSED DURING THE RECOVERY OF THE ACFT. LATER THAT EVENING; I CYCLED THE LNDG GEAR ON JACKS AND REFILLED THE NITROGEN BRAKE SYS. AFTER TAXIING THE ACFT TO VERIFY THAT WITH THE BRAKE SYS FULL; THE BRAKES OPERATED NORMALLY; I DEPARTED ZZZ TO FLY HOME WITHOUT INCIDENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ACFT INCURRED MINOR DAMAGE AND THE CAUSE OF THE LOSS OF BRAKING WAS JUST PLAIN RUNNING OUT OF NITROGEN. EACH TIME THE LNDG GEAR IS RETRACTED; THE NITROGEN PRESSURE STOPS THE ROTATING WHEELS AND SLIGHTLY DEPLETES THE LIMITED NITROGEN SUPPLY. THE NITROGEN BOTTLE PRESSURE WAS CHKED ON THE PREFLT CHK AND APPEARED ADEQUATE FOR THE FLT.

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.