MD-11
Maintenance Airframe; Maintenance Powerplant
Maintenance Lead Technician 2; Maintenance Technician 18
Other / Unknown
Aircraft Equipment Problem Less Severe
General Maintenance Action
Procedure; MEL; Aircraft
We had a Potable Water System Pressurization Air Compressor on MEL. During Removal/Replacement (R/R); found [Air] Pump and Cannon plug very hot to touch. MEL does not require a Circuit Breaker (C/B) to be pulled or the Cannon plug to be removed. I think this creates a fire hazard.  If pump is seized; as this one was; an overheat condition is possible.  This is much more likely on the ground as the pump is only powered when the APU and engines are 'Off'; but if the timing was right; a fire could start and remain undetected until after take off.
Reporter stated the Potable Water System tank is located in the Lower Lobe Forward Cargo compartment left-hand sidewall; outboard of the cargo pit sidewall panels. Smoke detectors are installed in the cargo area; but not the sidewalls. Reporter stated no cargo tape is applied to the cargo pit sidewall panel butt seams. Instead; thin metal strips are installed where cargo tape would normally be. Halon is the Fire retardant. A Pressurization Air Compressor pump failure is not a common occurrence. But; reporter still feels the overheated seized pump motor and Cannon plug are good reasons to add a Maintenance (M) Procedure to MEL 38 for deferral of the Potable Water System Air Compressor pump. Removing the Cannon plug as part of the MEL deferral requirement would reduce the potential for a fire to develop. Reporter has twenty plus years in aircraft maintenance.
A Lead Aircraft Maintenance Technician (AMT) reports about a potential fire hazard that could develop in the Lower Lobe Forward Cargo compartment outboard sidewall on MD-11 aircraft. Reporter found a deferred Potable Water System Pressurization Air Compressor pump and Cannon plug very hot to touch during Removal/Replacement (R/R) of the deferred pump. MEL does not require a Circuit Breaker (C/B) pulled or Cannon plug be disconnected for the deferral.