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A line mechanic was informed that a B737-300 pilot wrote-up a right main landing gear (medium large transport) inboard (#3) brake wear pin that showed less than 1/16' of an inch wear remaining. Mechanic had accomplished a wear pin measurement when the brakes were still hot during an overnight check; using only brake accumulator pressure for setting the brakes.
| Attributes | |
| ACN | 962056 |
| Time | |
| Date | 201107 |
| Local Time Of Day | 0001-0600 |
| Environment | |
| Light | Night |
| Aircraft 1 | |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Parked |
| Person 1 | |
| Function | Technician |
| Qualification | Maintenance Airframe Maintenance Powerplant |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy |
Narrative:
Mechanic X accomplished overnight check on B737-300 aircraft. Jobcard step in question # 15; 'check extension of main landing gear (medium large transport) brake return [wear] pins and replace brake if wear pin is 1/16' of an inch or less'. I checked all brake return pins; all were over 1/16' of an inch. Aircraft had been at gate for approximately 15 minutes. All brakes were hot and emergency brakes were set when brake return pins were measured. Pilot write-up in logbook for right medium large transport inboard [#3] brake wear pin nearly flush. Brakes had been set for approximately 15 minutes. Brake accumulator could have bled [hydraulic] pressure off. Both of which would make brake wear pin extend further.mechanic Y on duty inspected brake and found wear pin 1/32' of an inch; with brakes set. Log page cleared; inspected #3 brake pin with brakes set 1/32' of an inch; within limits per aircraft maintenance manual (amm) 32-41-41; figure 601. Condition of brake cold and brakes just set. Note: #3 brake was changed for company convenience on a daily check. Suggest waiting until brakes have fully cooled off. Set emergency brake and take wear pin measurement within five minutes from time emergency brake is set.
Original NASA ASRS Text
Title: A Line Mechanic was informed that a B737-300 pilot wrote-up a right Main Landing Gear (MLG) inboard (#3) brake wear pin that showed less than 1/16' of an inch wear remaining. Mechanic had accomplished a wear pin measurement when the brakes were still hot during an Overnight Check; using only brake accumulator pressure for setting the brakes.
Narrative: Mechanic X accomplished Overnight Check on B737-300 aircraft. Jobcard Step in question # 15; 'Check extension of Main Landing Gear (MLG) Brake Return [wear] pins and replace brake if wear pin is 1/16' of an inch or less'. I checked all brake return pins; all were over 1/16' of an inch. Aircraft had been at gate for approximately 15 minutes. All brakes were hot and emergency brakes were set when brake return pins were measured. Pilot write-up in logbook for right MLG inboard [#3] brake wear pin nearly flush. Brakes had been set for approximately 15 minutes. Brake accumulator could have bled [hydraulic] pressure off. Both of which would make brake wear pin extend further.Mechanic Y on duty inspected brake and found wear pin 1/32' of an inch; with brakes set. Log page cleared; inspected #3 brake pin with brakes set 1/32' of an inch; within limits per Aircraft Maintenance Manual (AMM) 32-41-41; Figure 601. Condition of brake cold and brakes just set. Note: #3 brake was changed for company convenience on a daily check. Suggest waiting until brakes have fully cooled off. Set emergency brake and take wear pin measurement within five minutes from time emergency brake is set.
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.