Date: 201811
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: Skyhawk 172/Cutlass 172
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Taxi
ATC / advisory: Tower ZZZ
Aircraft component: Normal Brake System
Component problem: Failed
Reporter organization: Personal
Reporter function: Pilot Flying
Reporter qualification: Flight Crew Commercial; Flight Crew Instrument
Human factors: Troubleshooting
Second reporter function: Instructor; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Less Severe; Ground Event / Encounter Object
Detector: Person Flight Crew
When detected: Taxi
Result: Aircraft Aircraft Damaged; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: I was acting as pilot in command and Pilot Flying; operating from the right seat. I had a CFI (not PIC or Pilot Flying for takeoff) on board who was going to act as a student later in the flight; in preparation for my upcoming CFI Checkride. I had just been given clearance to takeoff on Runway XL at ZZZ; by Tower. I was demonstrating a short/soft field take off procedure. I taxied onto runway and was aimed at the end of the runway to use all available distance; attempted to turn right to line up with the runway center-line and had the right brake depressed all the way possible with no braking action noted on the right side of the aircraft. Aircraft was still aimed at the runway end identifier lights and immediately pulled idle power and tried right rudder/nose gear to attempt to avoid lights. Aircraft turned slightly to right but was unable to stop in time from impacting the propeller with 1 runway end light. Light appeared to be damaged. I immediately informed the tower that the aircraft was disabled on the runway and that the traffic that was on final needed to go-around. I then notified the tower that I was going to shutdown aircraft and manually reposition the aircraft on the runway so that we could taxi off the runway. I was granted permission and then shut down the aircraft and exited the aircraft. Upon exiting the aircraft I reached down and touched the lower brake line and noted brake (Pink/red) fluid. My passenger and I repositioned the aircraft and got back in to start up and taxi off the runway. I contacted the tower and gave a report that we had impact with a runway light and that we were under our own power and requested taxi back to the Maintenance Ramp. We were granted clearance to exit the runway via the first taxi way and were switched over to ground freq. As I switched onto Ground; I noted the controllers mentioning that our aircraft had a blown tire. I gave them a report that we were under our own power and that we had a right brake failure; not a flat tire and that we did have impact with a runway end identifier light. I was able to taxi back to the ramp and verified that the right brake was not responding. I pulled onto the ramp and shut down. We inspected the aircraft for damage and noted a nick and slight bent/edge on the propeller. No other damage was seen or noted besides brake fluid on the right main gear; I could not find the origin of the leak by visual inspection. During the preflight walk around; and during the start of the aircraft for the first flight of the day; I noticed no unusual stains or puddles of fluid on the ground around the main gear. Both pilot stations; left seat and right seat tested their brakes and there was no notice of an issue; both sets of brakes left and right side worked. We also had to make multiple right hand turns and the brakes worked correctly. The brakes also worked correctly during run up and thorough about 3-5 minutes of taxi in which the brakes were used multiple times.


Second narrative: I was sitting in the left pilot seat as a passenger/instructor. The pilot at the controls was sitting in the right pilot seat. No other passengers were on-board. ATC cleared our aircraft for takeoff and the other pilot on the controls was going to demonstrate a short field takeoff using all available runway. We taxied to the edge of the runway to use all available runway. We needed to turn right to line up on the center-line. The airplane started to get close to the edge of the approach end of the runway where the Runway End Identifier Lights (REIL) are located and was not turning right to the center-line. The pilot on the controls noted that he was unable to turn right due to no wheel braking on the right brake pedal. He pulled the throttle to idle and did his best to not hit more REIL's. Pressing the left brake in an attempt to stop the airplane from taxiing forward would have resulted in a hard left turn into more REIL's. The aircraft propeller struck one REIL and the airplane stopped. The pilot on the controls notified ATC and the two of us exited the airplane to physically re-position the aircraft. The engine; magnetos switch; and master switch were turned off prior to us exiting the airplane to re-position it. ATC also gave us permission to do so. We re-positioned the airplane and safely taxied it back to the ramp. We did not notice any brake fluid leaks during the preflight check. Both sets of brakes were tested prior to first taxi. The brakes were tested again during engine run up; and no issues were noted. Both wheel brakes were used during taxi from the ramp to the hold short line near the runway and no issues were noted.


Synopsis: C172 pilot and instructor reported right main brake failure; resulting in loss of control; and prop contact with runway light.