Date: 201404
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Night
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight phase: Parked
Aircraft component: Main Gear
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Communication Breakdown
Second reporter function: First Officer; Pilot Flying
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew
When detected: Pre-flight; Aircraft In Service At Gate
Result: Aircraft Aircraft Damaged; General Maintenance Action; General Flight Cancelled / Delayed
Contributing factors: Staffing; Aircraft; Human Factors
Primary problem: Aircraft

Narrative: First Officer (F/O) did walk around last night in ZZZ; Gate X; Flight ZZZ-ZZZ1.  Push time scheduled late evening.  Called Maintenance with gripe concerning #1 Main Landing Gear (MLG) Tire Brake pins being below flush. Aircraft a B737-800.  Waited 30-minutes.  Single Maintenance Technician comes out and tells us the pins are above flush. F/O and I point out to him that two are; two are not.  We want the Brake System fixed.  He departs. (My assessment: he just wanted to get away so he could go home.)  About 30-minutes later (and after ZZZ Operations deplaned the passengers); two COMPETENT technicians arrive and diagnose the problem. They claim the delay in arriving was due to a Shift change.  The real problem is that two of the brake pucks are fused to the Brake and Wheel Assembly with associated metal damage and fragmentation.  Some parts are the diameter and length of my thumb.  No mention of whether the [tire] Fuse plugs had melted.  Solution:  Change the entire MLG tire; wheel; axle and brake assembly.    Maintenance technicians comment that damage was so bad that the Wheel Assembly could have catastrophically failed upon next Takeoff or Landing.  The previous inbound crew [into ZZZ] had taxied to the gate with no apparent problems or issues.  We departed ZZZ about 2.5-hours late. Everything worked fine thereafter. Recommend sending competent Maintenance technician to aircraft the first time. ZZZ Maintenance took a long time to respond to my request for service. Equipment malfunction.

Callback: Reporter stated he had talked with the previous inbound flight crew and they did not have any indications of a faulty brake or tire. The left Main Landing Gear (MLG) Outboard (O/B) tire fuse plug did not blow and the left O/B brake did not appear to be overheated.  But two of the four Brake Wear pins on the damaged brake were below flush. He doesn't remember whether the forward or aft wear pins were below flush. The other two wear pins were in serviceable range for wear; but may have been stuck. The O/B brake started falling apart; parts falling off; when technicians began removing the tire and brake. Classic B737s have a total of two Brake Wear pins for each brake; one forward and one aft compared to the NexGen aircraft that have four wear pins per brake.

Second narrative: I did walk around last night in ZZZ.  Push time scheduled late evening. Called Maintenance with gripe concerning # 1 Main Landing Gear (MLG) Tire Brake pins being below flush. Aircraft a B737-800.  The real problem is that two of the brake pucks are fused to the Brake and Wheel Assembly with associated metal damage and fragmentation.  Some parts are the diameter and length of my thumb.  No mention of whether the [tire] Fuse plugs had melted.  Solution:  Change the entire MLG tire; wheel; and brake assembly.  Maintenance technicians commentedthat damage was so bad that the wheel assembly could have catastrophically failed upon next takeoff or landing.


Synopsis: A Captain and First Officer report Number 1 Tire Brake wear pins on the left Main Landing Gear (MLG) were found below flush during a walkaround on a B737-800 aircraft. Two of the brake pucks were fused to the Brake and Wheel Assembly with associated metal damage and fragmentation. Maintenance Technician noted Wheel Assembly could have catastrophically failed upon next takeoff or landing.